Talk:TRAPPIST-1/Archive 1

natural satellites of the exoplanets
Would these even be possible or offer more or potentially equal chances of habitability or possibilities of liquid water or ocean worlds


 * Any satellites of any of these 7 planets would necessarily be much smaller than the planets, and therefore would not likely have liquid water. A body needs enough mass and gravity to hold an atmosphere. No atmosphere, any liquid water evaporates and is lost. One of the reasons these planets are exciting is that they are the right size and temperature to have liquid water.4.31.13.17 (talk) 19:08, 24 February 2017 (UTC)

merge all planet pages onto star page
Should be moved because b, c and d articles all are the same, with little variations and little detail. --MarioProtIV (talk) 21:17, 13 May 2016 (UTC)


 * Wait. There will be more data coming up regarding the planets with follow up studies.Quantanew (talk) 04:20, 15 May 2016 (UTC)
 * These articles have barely been touched since these comments. Some numbers have been updated (and are now seriously out of date) but they are still pretty little stubs repeating information already in this article. Lithopsian (talk) 22:19, 22 February 2017 (UTC)

Closest transiting planets?
Is this the closest star with transiting exoplanets known?--Roentgenium111 (talk) 17:03, 28 June 2016 (UTC) One of the closest at least. Quantanew (talk) 13:50, 30 June 2016 (UTC)
 * Nope... Proxima Centaury b is the closest known exoplanet, 4.2 light years from earth. See List of nearest exoplanets (there are at least 11 "potentially habitable" exoplanets, on 38 confirmed and 78 total, closer than those in Trappist-1 system) — Preceding unsigned comment added by 62.18.143.111 (talk)
 * I was talking about transiting exoplanets.--Roentgenium111 (talk) 19:59, 23 February 2017 (UTC)
 * Alpha Centauri Bc "On 25 March 2015, a scientific paper by Demory and colleagues published transit results for Alpha Centauri B using the Hubble Space Telescope for a total of 40 hours.[99] They evidenced a transit event possibly corresponding to a planetary body with a radius around 0.92 R⊕." HTH Kiore (talk) 06:40, 24 February 2017 (UTC)
 * Okay, but this is hardly a known planet. The paper does not even dare to give it a label like "Bc", which seems to have been a WP invention... --Roentgenium111 (talk) 16:29, 24 February 2017 (UTC)

add specific gravity to planets list
When somebody gets this data, would be nice to see the specific gravity of each of the planets where available. (And the relation to Earth's since that's really our only frame of reference...) --Enorl76 (talk) 19:13, 22 February 2017 (UTC)
 * That will probably need to wait for radial velocity observations to be complete. Kortoso (talk) 23:22, 23 February 2017 (UTC)

Make this page about the system rather than the star
Given that the NASA announcement is about the system as a whole rather than the star, and planets being of high importance, I suggest that we make this page about the system rather than the star. The title would then be something like "The TRAPPIST system". -- Sharanbngr (talk) 19:24, 22 February 2017 (UTC)
 * It's normal to name articles after stars, including where the system is the main focus. Rothorpe (talk) 19:34, 22 February 2017 (UTC)
 * That is highly atypical for Wikipedia articles on exoplanetary systems. It's fine as it currently is, being about the star with details about the associated system. Separate articles for the planets may follow once they become notable enough. — Huntster (t @ c) 19:36, 22 February 2017 (UTC)
 * I wasn't aware about the existing protocol. Thanks for the clarification Sharanbngr (talk) 19:40, 22 February 2017 (UTC)
 * It's good to have consistency among the exoplanetary systems, but note that this "protocol" is inconsistent with how we treat our own system: The article Sun doesn't even mention all of its planets, which are detailed only in Solar System. --Roentgenium111 (talk) 16:17, 24 February 2017 (UTC)

Order of planets wrong
Some of these planets were discovered a year ago so the "artist's concept" image you're using is wrong. Compare it with the table of data, planet d is the farthest one out. Enough people are spreading this confusion, I hope you get it corrected here. 207.161.172.171 (talk) 19:45, 22 February 2017 (UTC)
 * It's shameful that even the NASA artist got it wrong. Planet d is the farthest one out, the order is b, c, e, f, g, h, d. 207.161.172.171 (talk) 19:51, 22 February 2017 (UTC)

Or is it the chart data and article on planet d that are wrong? TRAPPIST-1, stellar object TRAPPIST-1 b, planet, semi-major axis: 0.0111±0.0003 AU TRAPPIST-1 c, planet, semi-major axis: 0.0152±0.0005 AU TRAPPIST-1 d, planet, semi-major axis: 0.0214+0.0007−0.0006 AU TRAPPIST-1 e, planet, semi-major axis: 0.0282+0.0008−0.0009 AU TRAPPIST-1 f, planet, semi-major axis: 0.0371±0.0011 AU TRAPPIST-1 g, planet, semi-major axis: 0.0451±0.0014 AU TRAPPIST-1 h, planet, semi-major axis: 0.063+0.027−0.013 AU 207.161.172.171 (talk) 20:06, 22 February 2017 (UTC)


 * Today's Nature paper named them in order of increasing orbital period, with b the 1.5 days planet, and h the ~20 day planet. So either the authors have it wrong, or The planets are designated in the order of their discovery here is wrong. Currently TRAPPIST-1d seems to be about the planet that is designated g in the paper. Gap9551 (talk) 22:02, 22 February 2017 (UTC)
 * Exoplanets are named in order of their discovery. However, in this case it is the same as the order of distance from the star, partly because the planets were not all discovered at different times. Somewhat (but not entirely) coincidentally, the first three planets discovered were the inner three, then the outer four were discovered (or at least announced) together, so the orders all match up. Describe away ...Lithopsian (talk) 22:16, 22 February 2017 (UTC)
 * That's not correct in the original nature paper planet d was the current planet g. They changed the name and the order. Quantanew (talk) 01:22, 23 February 2017 (UTC)
 * The new Nature paper says These signals correspond to four new transiting planets, named, respectively, TRAPPIST-1d, TRAPPIST-1e, TRAPPIST-1f and TRAPPIST-1g, suggesting that it is h, not g, that corresponds to the old d. But the orbital period was quite uncertain in the 2016 Nature paper so maybe it wasn't entirely clear which planet they saw then (apart from b and c). Gap9551 (talk) 15:17, 23 February 2017 (UTC)
 * No substitute for reading the paper I suppose :) It describes that the two transits originally used to identify "TRAPPIST-1d" were from different objects. Further observations showed that the "different objects" were four planets now named d to g. TRAPPIST-1h is described later, somewhat tentatively, on the basis of a single transit seen from Spitzer. I suppose it is somewhat a matter of semantics whether you describe d to g as four new planets (and minus one planet previously named d), or three new planets (going from 3 to 6 planets). Overall, the paper describes 7 planets where previously there were 3, but it isn't quite true to say that the four extra ones are d to g or that "old d" is now called h. Lithopsian (talk) 15:37, 23 February 2017 (UTC)

Metallicity
The metallicity of "0.04 ± 0.08" makes no sense (makes it sound likely to have an impossible negative metallicity), and calling it "109% the solar amount" when the Sun is listed at 0.0122 sounds wrong both mathematically and in terms of significant digits. Capybara (talk) 20:09, 22 February 2017 (UTC)


 * Negative metallicity is not impossible at all, it just indicates having less heavy elements than our Sun.Mihaiam (talk) 20:35, 22 February 2017 (UTC)


 * See the entry on metallicity. Stellar metallicities are typically cited as [Fe/H] or [M/H]. This is logarithmic and relative to the sun, so a star with 1/10th the metal content (relative to hydrogen) of the sun would have [Fe/H] = -1.Dab8fz (talk) 00:12, 23 February 2017 (UTC)


 * Aha, that makes sense, sorry for misunderstanding. But it's still misleading to quote it at "109% of the solar amount" when the error indicates between 96% and 113%.  How about changing that to just "with a metallicity similar to the sun's."? Capybara (talk) 18:51, 24 February 2017 (UTC)

4–5 trillion years
When the article says 4–5 trillion years it means 4-5.000.000.000.000? -Theklan (talk) 20:18, 22 February 2017 (UTC)


 * , yes, trillion (short scale). Dwarf stars have extremely long and stable lives. — Huntster (t @ c) 20:30, 22 February 2017 (UTC)
 * Thanks ! Just making the translation for Basque Wikipedian and wondering if I had to write down billion instead of trillion. -Theklan (talk) 20:38, 22 February 2017 (UTC)

Sorry but, hasn't the universe only existed for like 8 billion years or something? Socialistboyy (talk) 21:38, 23 February 2017 (UTC)socialistboyy
 * , see age of the universe. It is about 13.8 billion years. — Huntster (t @ c) 01:49, 24 February 2017 (UTC)

Is it a red dwarf?
The first occurrence of "red dwarf" is here more than halfway through the article: "red dwarf stars are subject to frequent, intense flares". It's not clear whether this statement even pertains to TRAPPIST-1. - Brianhe (talk) 23:58, 22 February 2017 (UTC)
 * The star is indeed a red dwarf, or at least a very massive brown dwarf. The spectral type is M8.2 +/- 0.1, so it's right in the expected range for flare stars.


 * The star is red (no blue light, little green light). The star is young and very unstable. The planets are all closer to the star than Mercury. Thus one side is lock to the star. How is this earth like? I know politics has spin, but science is not where spin should be. "Habitable zone." label is joke.Telecine Guy (talk) 05:08, 23 February 2017 (UTC)


 * "Habitable zone" is indeed a potentially misleading term, but it has some sense to it. It excludes large regions of every system where people think planets are uninhabitable simply based on where they are.  Within the zone, a lot of things have to go right besides just location -- remember, Venus and Mars are Earthlike planets near the border of the habitable zone.  But the point is that based on what little is currently known you actually have to go there, measure temperatures, even dig through the soil and look for life before you can say they are definitely uninhabitable.


 * I would like to see more about whether large moons are possible for planets in these orbits around red dwarfs, since I would think that a large moon could tidally lock the planet onto itself and leave it with normal day and night. Certainly NASA thinks moons are possible - see File:NASA-RedDwarfPlanet-ArtistConception-20130728.jpg (if we find a bit more suggestion we might even use it as an image here).  The moons themselves, if large enough, might even be habitable; or one of the transiting planets might actually turn out to be a double planet.  Providence has granted us this fascinating system, but it's up to us to see what we can make out of it. Wnt (talk) 13:30, 23 February 2017 (UTC)


 * Red dwarfs are far more variable and violent than the Sun. Red dwarfs are often covered in starspots that can dim their emitted light by up to 40% for months at a time, a stable ones variable is only, what 10% or 5 %. Our sun variable output is about 0.1 %. The planets here are not "Earth like" other than maybe is size, but that is where it ends. Mars is not Earth like, its gravity is too weak, Mars did not have enough gravity to hold on to its water or atmosphere. Gravity on Mars is so low a person could not "walk" on Mars, they would need to hop like men on the moon did. Words have meaning and "Habitable zone" has lost its meaning, just has honesty has been lost on this topic. What is the definition of "Habitable zone"? What does the average person think it means? Telecine Guy (talk) 06:01, 24 February 2017 (UTC)

Inclinations
As far as I know, the inclinations of these planets are all close to 90 degrees because they were all found by transiting the star. They are in other words inclinations relative to a plane perpendicular to the Earth-TRAPPIST1 axis. If you have a handy source for this you should explain it.

Also, it makes me wonder... is the TRAPPIST-1 star's rotation axis exactly 90 degrees (give or take at most a few tenths) perpendicular to the Earth-TRAPPIST1 axis? Or is it further off? (If it's further off does that mean there are probably dozens of other planets around the dwarf that don't transit?) Wnt (talk) 00:00, 23 February 2017 (UTC)
 * I wonder if the rotation axis of the star can be measured. You'd probably need to measure Doppler shifts on different sides of the star disk, which the star may be too small for. But likely the axis will be perpendicular to the plane in which the planets orbit. If anything is known about the axis orientation it would be interesting to add it to the article. I doubt there are many more planets at larger inclinations, at least nearby the star. The whole system is very "flat", all planets transit within 0.42 stellar radii from the middle, based on semi-major axes and inclinations. (The orbital period gives the orbital velocity, which, combined with the transit duration, tells us if a planet is transiting the star near the middle or closer to the edge on either side.) Non-transiting planets near the star would also have had a noticeable gravitational effect on the transit timing variations (that were used to estimate the planet masses). Gap9551 (talk) 15:38, 23 February 2017 (UTC)


 * The rotational axes of stars does not always correlate with the orbital planes of their planets. Kortoso (talk) 23:26, 23 February 2017 (UTC)

Alternative version
Today's top story on ITN and Google revolves (literary) around an Ultra-Cool Dwarf Star. I was immediately struck by the term "ultra-cool" dwarf star and got a quite different picture in my mind of what ultra-cool was. A quick Google picture search confirmed this view. So here is the alternate version of this new celeb. :) cart -Talk  13:37, 23 February 2017 (UTC)

Earth-Like?
I think the term "earth like" may be better re-stated as 'earth-sized'. The term 'earth-like' would seem to mean a plant that is, well, like the earth. That is: it rotates (e.g. isn't tidally locked to the primary), has an atmosphere (that wasn't stripped away by the primary), and would likely support earth-type life (which the article states (in two places) as being un-likely.


 * We have a long way to go before we can say any more about any exoplanet than its size and mass. Kortoso (talk) 23:28, 23 February 2017 (UTC)


 * We do know that the TRAPPIST-1 planets are likely tidally locked. Also, the atmospheres of b and c have already been studied (though not conclusively) in the current paper. --Roentgenium111 (talk) 16:06, 24 February 2017 (UTC)

They haven't discovered it fully yet I think.....!!! Dlritesh (talk) 11:50, 7 March 2017 (UTC)

Is there water on the surface?? Dlritesh (talk) 11:51, 7 March 2017 (UTC)

Discovery date of TRAPPIST-1
When was the star itself first observed? Was it known of before the first three planets were discovered in 2015? If not, how did the astronomers know to focus their gaze on that patch of sky? 2A02:C7F:DA15:9100:7C32:8C43:7135:BE4A (talk) 17:18, 23 February 2017 (UTC)


 * The star was "known" in the sense that it existed in the catalogues of previous sky surveys. I believe it was first observed by the 2MASS survey (along with many, many other stars). It did not get any attention until the first planets were observed.Dab8fz (talk) 17:48, 23 February 2017 (UTC)

Trappist-type planets and history of astronomy
Speculation I know - but 'entities on such planets' who are in a position to develop the science of astronomy will have a (local)heliocentric concept of their solar system from the start, rather than 'the pre=Copernican-Earth-centric system' that once prevailed (a simplification for convenience). Jackiespeel (talk) 19:15, 23 February 2017 (UTC)

Very confusing planetary data statistics on this page vs the planet-specific one
Title says it all. For example TRAPPIST-1d is stated in the table to have a mass of 0.41±0.27 M⊕ (giving a maximum of ~0.68 M⊕), while on the article for TRAPPIST-1d it is stated to be in the ballpark of 1.7 M⊕, much higher than what this article claims. The radius is another point of dispute, with the table stating it as 0.772 ± 0.030 R⊕ (upper bound of ~0.80R⊕) yet the article states the radius as around 1.16 R⊕. Admittedly these numbers are still very ambiguous, but it would be nice to be consistent between the two groups of data. TRAPPIST-1d is the only case where this issue is pretty prevalent, all the other planets have stats common to each other as far as I can tell. I would edit one to state data that matches the other but at this point I am unable to tell from the sources which of the two is the more accurate, regarding the large error bars inherit in this discovery.

EDIT: the way these articles are usually structured this article shouldn't even be delving into too much detail as to the planets, and instead should just have names and perhaps a sentence or two with the bulk data in the planet specific article. Caelus5 (talk) 00:04, 24 February 2017 (UTC)
 * The data in the new Nature paper are the most accurate available. Gap9551 (talk) 02:49, 24 February 2017 (UTC)
 * The article on TRAPPIST-1d was probably originally created based on the information in the first Nature paper by Gillon et al., published in May 2016. The two transits on which the original '1d' candidate was based turned out to be due to two different objects, so that candidate has been dropped altogether in the 2017 Nature paper. I suspect the article TRAPPIST-1d may need to be updated using data from the more recent paper. --Robert.Allen (talk) 03:00, 24 February 2017 (UTC)
 * Regarding coverage of the planets in the system, it is a highly unusual and surprising planetary system because of the large number of earth-like planets (rocky and many in the habitable zone), so I don't think providing more detailed information on each of these in the main article is out of place. It is helpful to include a detailed summary all the planets for purposes of comparison. --Robert.Allen (talk) 03:00, 24 February 2017 (UTC)
 * Okay, thanks for the swift reply. Judging by this I take it the TRAPPIST-1d article is the one in need of updating, is it not? Caelus5 (talk) 04:24, 24 February 2017 (UTC)
 * Yes. --Robert.Allen (talk) 05:02, 24 February 2017 (UTC)

Doesnt matter much if we might be wrong with some of the Math,

After we explore our Solar System.. The first Star we going too after that.. is that one.. We'll learn more then.. — Preceding unsigned comment added by 81.155.215.141 (talk) 06:54, 25 February 2017 (UTC)

TRAPPIST-1 System
I created an article on TRAPPIST-1 System article, but it needs major expansion. Star system section in this article needs to be moved. I ask for assistance. Friy Man talk 13:10, 27 February 2017 (UTC)
 * FWIW - the newly suggested TRAPPIST-1 System article created by User:FriyMan seems unnecessary at this time - the present articles (ie, TRAPPIST-1; TRAPPIST-1b; TRAPPIST-1c; etc) seem sufficient to describe the TRAPPIST-1 star and exoplanetary system imo - however - Comments Welcome from other editors of course - in any case - Enjoy! :) Drbogdan (talk) 15:01, 27 February 2017 (UTC)
 * I agree, we probably really only need one article. The star itself is mainly notable because of its planets. Probably better to keep the information in one place for now. --Robert.Allen (talk) 16:10, 27 February 2017 (UTC)
 * Yes. See section above. I'm going to be bold and redirect that article back to this one as being highly premature in its creation. — Huntster (t @ c) 16:15, 27 February 2017 (UTC)

Red versus brown dwarf: does anyone have a figure for the lithium, etc.?
In a tribute to the universal moronicy of Man, I haven't yet laid hands on that locked-up Nature article. We ought to have a red vs. brown discussion - in the article, but here might be a place to start. Some of the conversations above suggest the star could be a brown dwarf. But my impression is a brown dwarf is distinguished by a lack of lithium burning, so that a star older than 100 million years with lithium is a brown dwarf. True, our articles go on to suggest that some stars may be defined as brown dwarf because they do lithium burning but nothing else - they therefore lose their lithium despite being brown dwarf - but only given a mass of > 65 Jupiter masses. TRAPPIST, as it happens, is "0.08 solar masses +- 0.009" = 0.071 to 0.089 solar masses = 74 to 93 Jupiter masses. So it is close enough to this boundary that an independent measurement of lithium seems informative. Brown dwarfs can be "up to 80 Jupiter masses" according to our article, and can be spectral class M, so this isn't that easy to figure out, mind. M8V is a class typical of the smallest and dimmest red dwarfs. Anyway, I'd like to see some description of what about the star suggests it's >= 500 million years old, whether its long predicted life is based on a solid knowledge of which type it is and so on. Wnt (talk) 01:13, 28 February 2017 (UTC)
 * Gillon et al 2016 : High resolution optical spectroscopy failed to detect significant absorption at the 6,708 A line of lithium (ref 36), suggesting the star is not a very young brown dwarf, rather it is a very low-mass main-sequence star [which is fusing H and has already burned all of its lithium]. "This is in agreement with its thick disk kinematics, its slow rotation (projected rotational velocity vsini = 6±2 km s-1), its moderate activity, and its reported photometric stability, all of which point to an age of at least 500 Myr (ref 13)." [I've omitted some of the other refs they cite. I have not yet come across a figure for the spectrum.] --Robert.Allen (talk) 02:55, 28 February 2017 (UTC)
 * If you look at Fig.2, you will see that the lack of lithium together with the known temperature puts a lower limit on the age. Ruslik_ Zero  19:38, 4 March 2017 (UTC)

I know this section is intended to suss out the purely scientific definition of whether this is a red dwarf system, but I should point out that many reliable sources state it as such, which is the measure by which our article should follow. As a sampling: NASA, NASA, Time, Popular Mechanics, Centauri Dreams, Business Insider, European Southern Observatory, The Daily Telegraph, Universe Today, Financial Times, and I could keep going with prominent reliable sources. Surely this warrants labelling it as such in the article? — Huntster (t @ c) 04:34, 28 February 2017 (UTC)
 * I don't really disagree with you, but it is interesting that neither of the two Nature papers from the Gillon group refer to TRAPPIST-1 as a "red dwarf", rather they call it an "ultracool dwarf". Either the authors themselves chose to call it that, or the Nature reviewers required them to. Presumably all of these web pages you have linked are ultimately based on the Gillon papers, so maybe somewhere along the line one or more of these subsequent authors decided to discard scientific caution and call it a red dwarf and others followed suit. --Robert.Allen (talk) 07:15, 28 February 2017 (UTC)
 * I can't deny there is a consensus for a red dwarf, but this article should go into scientific detail. If in business "it's not what you know but who you know," then in science "it's not what you know but how you know."  The more we can figure out about the history of this journey the better the story we can write about it. Wnt (talk) 02:06, 1 March 2017 (UTC)

Artist's impression/Artist concept
Inasmuch as there don't seem to be any 2MASS photographs of TRAPPIST-1, I'm fine with artist's impressions and artist concepts, but we might need to fine tune the nomenclature. The lead illustration is based quite closely on transit data; the others feature suitable embellishments (which lies quite firmly in the venerable Chesley Bonestell tradition of Space art). For that matter during the Space Race itself "Artist's impression" was standard NASA lexicon. NASA employed artists four years after its founding, and for good reason!

http://newatlas.com/how-are-planets-painted/42763/

kencf0618 (talk) 22:45, 1 March 2017 (UTC)

Water loss
It's too bad, although not that surprising, that the fact that these planets may not have water was pulled from the lead. This source concludes that one or two of the planets *may* have water, depending on what models you prefer to use, and what starting composition you feel like using. Given that those researchers felt it necessary to write a paper arguing that water is not completely out of the question, that's anything but a compelling reason to remove any mention of doubt of it from the lead. And, a pet peeve of mine: many readers won't understand that "habitable zone" =/= "habitable". Maybe some alternative wording would be more palatable? Geogene (talk) 00:49, 2 March 2017 (UTC)
 * Geogene (talk) 00:50, 2 March 2017 (UTC)
 * You failed to provide a reference for your statement, so I removed it. If we can find a reference that supports it (other than a random blog post), we should include it. Such a critique might be published in the near future. In any case, we should not formulate our own critique based on sources that don't mention TRAPPIST-1. That would constitute original research. The reference we have, Gillon et al 2017, states on p. 458 that the authors ran a three-dimensional climate model (ref 26, developed for another red dwarf, Proxima Centauri b). Gillon et al assumed the TRAPPIST-1 planets are tidally synchronous (and also apparently that they have earth-like atmospheres) and deduced that planets e, f, and g could harbor water oceans on their surface. The same model results in a runaway greenhouse scenario for planets b, c, and d. They also cite Bolmont et al 2016, implying they have taken UV irradiation from the star into account, but few details are provided. --Robert.Allen (talk) 06:32, 2 March 2017 (UTC)


 * There are two estimates, one fifty times higher than the other. Certainly we should mention both, though not necessarily treating them as definitive. Wnt (talk) 17:49, 2 March 2017 (UTC)
 * I read Snellen's 'News & Views' item in the same issue of Nature. It may be be what we need for the lead. I've tried adding something general to the end of the second paragraph based on it. We can always add more specific arguments to the body of the article. --Robert.Allen (talk) 19:43, 2 March 2017 (UTC)
 * I see it's been removed as "redundant padding", which I suppose is probably true. --Robert.Allen (talk) 03:46, 3 March 2017 (UTC)
 * I don't think so, but if is going to hype the hell out of this article, there's probably enough of them to do it. Geogene (talk) 00:18, 4 March 2017 (UTC)
 * Wait, what? Please clarify. kencf0618 (talk) 00:38, 4 March 2017 (UTC)
 * Sorry, my meaning there should be clarified. In my experience, there are some types of articles that will be hyped and that can't be helped. Articles involving the possibility of alien life is one of those types. In this case, there appears to be controversy over whether any of these planets should be expected to have water on them, given hydrodynamic(?) escape and the radiation environment they're apparently being bathed in. It's not clear what the majority viewpoint is from the limited sources available, but as I expected one is being downplayed in the article in favor of the other. Geogene (talk) 00:48, 4 March 2017 (UTC)
 * I thank you for your explanation. Media reports aside, the standard nomenclature from the scientists involved use "Earth-sized" rather than "Earth-like," AFAIK. We await more data from the astronomers, and more Wikipedia nuance regarding this habitability zone and that. kencf0618 (talk) 01:26, 4 March 2017 (UTC)
 * We still have a lot to look for where the water estimates are concerned. When two vary by a factor of 50, I gotta wonder.  When the difference between Earth and Mars is supposedly the magnetic field and the potential values of magnetic fields on the TRAPPIST planets aren't discussed in either of those two papers, I gotta wonder.  I think it is a fair expectation that the planets will turn out to be unsatisfactory in some clear way, but not to know is a very exciting thing.  We live on the one planet in the Cosmos that was sculpted by the loving hand of the Creator, and/or the anthropic principle, to be a homeworld of living things.  The rest ... we have to find out about. Wnt (talk) 01:19, 4 March 2017 (UTC)

Coordinate system of planetary data
The inclination value 89° looks very strange for such synchronized system. What is the coordinate system? It must be not analog of heliocentric coordinates for the central star, but some other coordinates. Anton Kopiev (talk) 18:01, 3 March 2017 (UTC)


 * The inclinations of exoplanet orbits (and stellar rotation axes) are given relative to our line of sight, where 90 degrees indicates the orbit is exactly along the line of sight. Planets which transit have inclinations near 90 degrees. Dab8fz (talk) 05:49, 6 March 2017 (UTC)

Science Outreach
Science outreach posted on an astronomical project's official website is hardly irrelevant. If the viral LIGO Chirp is relevant, so is this; the graphic novel does a good job of laying out the basic scientific facts, albeit in an anthropomorphic context. kencf0618 (talk) 01:05, 4 March 2017 (UTC)
 * If it's that educational, then I won't oppose a specific link pointed directly to the graphic novel in the "Further Reading" section. I oppose mentioning in the article body unless reliable independent sources are discussing it. And, I oppose a link to other speculative fiction, or any compilation of speculative fiction, in the "further reading" section because it's not clear that those works are of sufficient educational value and are being factchecked. It is somewhat unusual that the discovery team appears to be publishing SF about their star on their webpage, but I contend that not all of that needs to be linked here. Geogene (talk) 01:09, 4 March 2017 (UTC)
 * Lack of lithium does itself prove that is a true star. Any object with a mass >0.065 than that of the Sun will burn hydrogen (and lithium) for some time but for it to be a star it needs to be more massive than about 0.072 Sun's masses to sustain this hydrogen burning. Ruslik_ Zero 17:01, 4 March 2017 (UTC)
 * I'm not sure why you added this comment here, but since you did, I will reply here. The TRAPPIST-1 article currently says optical spectroscopy fails to detect lithium suggesting it is a main-sequence star rather than a very young brown dwarf. Use of the word suggest follows almost exactly what we find in Gillon et al. 2016. These authors always refer to the star as an "ultracool dwarf", not a red dwarf. Clearly at 0.08 ± 0.009 M☉, it is a borderline case. However, we could add some more details which the Gillon et al. 2016 article lists in support of the idea. --Robert.Allen (talk) 18:27, 4 March 2017 (UTC)
 * Sorry, the comment was intended for a section above. Ruslik_ Zero 18:58, 4 March 2017 (UTC)

I think it's clear that the Google Doodle stuff might be relevant to that page, but it's not relevant to the star itself. A company that makes a quick drawing for any given day's headline shouldn't get a mention in every single Wikipedia article about every single headline from every single day! I haven't decided about the novel yet, but I took the tag off it - we know there's a disagreement and should work it out here, no need to have big ugly tags about a disagreement we already know about. Wnt (talk) 01:31, 4 March 2017 (UTC)
 * Fair enough. There is an intersection of science outreach, mass media and social media reaction to major scientific discoveries, and Wikipedia policies, after all. kencf0618 (talk) 01:44, 4 March 2017 (UTC)

(ec) OK, I looked at the site -- despite some suggestions above, I so far see no evidence that this site has anything to do with the discovery team. I don't see any "lepithec" on either Nature paper or anywhere else in our references section! Until I see evidence to the contrary, I think this is just some guy who could draw well and realized there was a ".one" TLD with a name to be taken. Now, we could have a link if the site is educational and useful, or properly reference and mention it if it is "notable" i.e. mentioned by secondary sources about TRAPPIST ... so far I'm not greatly convinced. If Lepithec himself is notable (in the Wikipedia policy sense) and has an article anywhere on Wikipedia of course it can be detailed there. Wnt (talk) 01:50, 4 March 2017 (UTC)

Formation
How did 7 near Earth sized objects form around a red dwarf with years that last only a few Earth days? It is not mentioned in the article. It is also not mentioned in the nebular hypothesis page on how such systems could form. Also, why is it not mentioned anywhere of the possibility that "exoplanets/planets" are just evolved/evolving stars and the modern edifice of astrophysics is misguided at best? How (myth)-busted does the nebular hypothesis (and all its variants that assume stars to be mutually exclusive of planets) need to get before it is trashed?Trilliant (talk) 15:21, 8 March 2017 (UTC)
 * It's probably too early to say much about the formation of the system. Gillon et al 2017 state that the masses and orbital parameters of the seven known planets are too uncertain to permit reliable predictions of the long-term dynamical evolution of the system. However, the simulations they ran did suggest that tidal heating might be strong enough to affect the planets' energy budgets and geological activities. --Robert.Allen (talk) 01:11, 9 March 2017 (UTC)
 * These objects have measured masses which are far too low to enable fusion in their cores, so they are unambiguously planets. Dab8fz (talk) 20:16, 10 March 2017 (UTC)

Planetary parameters
Yes, the initial discovery of the planets was through the transit method. This technique is not useful for determining the mass of these planets, but usually only their radius. What's missing here is how the mass of these planets was derived. Was this data gathered at the same time? Later? Is it still being refined? Kortoso (talk) 20:57, 9 March 2017 (UTC)
 * They can determine their mass from the differing time of transit, combined with radial velocity differences. exoplanetaryscience (talk) 23:21, 9 March 2017 (UTC)

Tidal locking and development of life
In the "Tidal locking" section it is written that ''"All seven planets are likely to be tidally locked (one side of each planet permanently facing the star), making the development of life there "much more challenging... Tidally locked planets would typically have very large temperature differences between their permanently lit day sides and their permanently dark night sides, which could produce very strong winds circling the planets. The best places for life may be close to the mild twilight regions between the two sides, called the terminator line."'' The questions are the next: 1) Why tidal locking will produce strong winds? For my opinion, the winds will be formed only when one side is heated (or cooled) at the first time; once the pressures are aligned, the air flow should stop. I.e. if both sides are constantly "hot" and "cold", how the wind can be formed? 2) For my opinion, the best place for life in the case of tidal locking are the dark sides, and not the terminator line. The "dark sides" are not really dark, so as they have several other planets visible in the sky as big "moons", which will illuminate the "dark sides" by a reflected light, which is much brighter than the light from a single Moon in our sky. In addition, the dark sides will be protected from UV and X-ray irradiation, which again makes them a better place for life. Krasss (talk) 22:07, 10 March 2017 (UTC)


 * There's no evidence that any of these exoplanets are tidally locked. It's based on sound science, but it's still speculation. I wouldn't want to make a big deal of it here on Wikipedia. Kortoso (talk) 22:59, 10 March 2017 (UTC)
 * 1- Winds don't work so much as a pressure equalization method as an effect of the inequality. In theory, there will be no wind when, and only when, every area is the same temperature. You're assuming that eventually the temperatures will equal out, but it's incredibly doubtful considering that the warm side will constantly be warm, and the cold side will constantly be cold. While I see you imagining that the pressure would equalize, at high enough elevations there will likely also be an equally strong warm wind moving the opposite direction. 2- Keep in mind that even with an atmosphere, dark sides of planets aren't that warm. Without major convection, you would end up with a similar temperature to that of the Moon (rotation period = about 700 hours), -243 F at times. Also, as it's doubtful that these planets would be stable enough with their near association to maintain a constant massive satellite, they're probably subject to regular true polar wander, which would make it difficult as well for life to survive, as it would have to periodically move around the planet to avoid eventual irradiation. exoplanetaryscience (talk) 23:52, 10 March 2017 (UTC)

Nomenclatura
It bis doubtful that Trappist-1 could be "ultra-cold star" as listed in the introduction by refrence to Gillon and al. paper. By definition, a ultra-cold star is a a drwarf star of spectral class Y which effective temperature is ranging between 448 and 248 K or 175°C and 25°C. Trappist-1 is thus well a brown dwarf with a effective temp. of ~2550 K. -- luxorion — Preceding unsigned comment added by 2001:7E8:DC0A:6A01:CDF:A2D3:5B78:5670 (talk) 12:58, 5 April 2017 (UTC)

Some sources to add
, and. Jo-Jo Eumerus (talk) 18:42, 1 January 2022 (UTC)
 * And these here since the website is currently acting up and I can't use them. Jo-Jo Eumerus (talk) 18:49, 1 January 2022 (UTC)
 * I guess that they don't have a good anti-robot system if it simply fails with an "end of file" error when sending too many requests. Jo-Jo Eumerus (talk) 12:04, 13 January 2022 (UTC)

updated masses
New paper on arxiv Updated Masses for the TRAPPIST-1 Planets includes mass of TRAPIST-1h. Uses data from K2 Mission Masses of others smaller than previous paper. Comment on arxiv page says submitted to ApJ. Should page be updated or should we wait until paper is accepted or data on http://www.trappist.one site is changed? Agmartin (talk) 16:17, 17 April 2017 (UTC)
 * Thanks for noticing this paper by Wang et al and adding your comment. We updated the Wikipedia article based on the Luger et al typescript on arxiv at the time it appeared. No one objected to doing that. Wang et al state that these new mass estimates predict a system that is relatively dynamically stable, unlike for the previous mass estimates of Gillon et al 2017. I would favor updating now, but it's important that we remember to compare the published paper when it appears to the draft version, so we can make any necessary revisions. This new paper makes some major changes to our view of the system. The estimates of the four outer planets' masses are consistent with pure water compositions. I suppose I don't need to mention that includes the three in the so-called habitable zone. We will need to make some important revisions to the text here, including the lead. --Robert.Allen (talk) 19:29, 17 April 2017 (UTC)
 * Much smaller and uncontroversial changes in that case, the period was in expected range and near resonance like the others, and a simple measurement of time between occultations. Unlike the calculations used to determine the masses, which is why I thought to ask instead of just changing the data as I did last time with the period.Agmartin (talk) 22:04, 17 April 2017 (UTC)
 * I have no objection to waiting until it is published. Maybe other editors will add some opinions here after they have had a chance to look at the paper more carefully. --Robert.Allen (talk) 01:14, 18 April 2017 (UTC)
 * Yes, these are really serious changes, resulting in none of the 3 HZ planets having an Earth-like composition. I think we should wait until this is reported in reliable secondary sources and/or accepted by independent researchers (or even Gillon et al. themselves). Note that http://www.trappist.one has not even been updated with the Luger results yet, so I wouldn't wait for an update there. --Roentgenium111 (talk) 09:24, 18 April 2017 (UTC)
 * Yes, I agree the www.trappist.one web site is not really helpful. After Wang et al. is published, there will probably be some secondary reports, but in any case we will have to mention their results, and how they differ from Gillon et al 2017. We cannot ignore their paper. We could easily modify the article to say the question of the actual planetary composition has not been settled, that is, we should no longer say that all seven planets are terrestrial. Actually I don't see Wang et al as very controversial. Gillon et al 2017's original mass values were always open to revision based on additional data, and their title referring to all seven planets as "terrestrial" is what could be regarded as controversial. --Robert.Allen (talk) 19:24, 18 April 2017 (UTC)
 * I'm glad that you agree now that we should no longer claim they're all terrestrial; IMO this claim wasn't even supported by Gillon's own data, which are after all indeed compatible with Wang's at the 3-sigma level. I think some weaker claim like "terrestrial-size" (or maybe "possibly terrestrial") would be compatible with both sets of data. Now that Gillon's data have already been replaced by Wang's in the "Planetary system" table and the paper is mentioned in some good-quality secondary sources (like ) we should also do this change now IMO. --Roentgenium111 (talk) 17:12, 11 May 2017 (UTC)
 * In my view, it was not a matter of my agreeing or disagreeing with you, since as Wikipedia editors it is not really our job to second guess what we find in the literature. The initial report on the seven planets of the TRAPPIST-1 system (Gillon et al 2017) described the planets as terrestrial, so that was what we correctly reported. Now we have a paper that modifies their conclusions, so we can report that. --Robert.Allen (talk) 19:50, 12 May 2017 (UTC)

https://arxiv.org/abs/1704.04290 (april 2017) published an new estimation of the exoplanet mass. You list them correctly in the text (table) but the drawing is not updated yet -- luxorion — Preceding unsigned comment added by 2001:7e8:c9f4:7f00:7125:cc:647a:dc6b (talk) 15:37, 15 September 2017

Longitude of periastron
Hi all,

I’m looking for the longitude of periastron for each of these planets. Any clue where I might find them? I have used Google to no avail…

Thanks in advance,

CielProfond (talk) 00:47, 16 May 2017 (UTC)

A seven-planet resonant chain in TRAPPIST-1
In Nature Astronomy pay-walled link but paper can also be accessed via link in space.com article look for Nature Astronomy. Agmartin (talk) 22:12, 25 May 2017 (UTC)
 * Oops, just noticed that it's the "A terrestrial-sized exoplanet at the snow line of TRAPPIST-1" from arxiv with a new title. Agmartin (talk) 22:18, 25 May 2017 (UTC)

Challenging the existence of orbital resonance
The mutual gravitational attraction between two planets passing each other in adjacent orbits can be decomposed into three vectors in space. They are analogous to the orthogonal forces produced by spacecraft thrusters at a ‘maneuvering node’ (http://wiki.kerbalspaceprogram.com/wiki/Maneuver_node): [1] ‘prograde/retrograde’ appear in succession in opposite directions during the passing and thus cancel each other out; [2] ‘normal/anti-normal’ can change the orbital inclination but would have negligible effect for coplanar orbits; and [3] 'radial-in/radial-out' reaches a maximum at conjunction of the planets and will have no effect on the shape of each orbit but will rotate both orbits in their own planes, moving the apotraps and peritraps in opposite directions around their respective ellipses. The ratio of orbital periods has nothing to do with those three effects, which puts the whole subject of ‘orbital resonance’ in doubt. Surely there must be plenty of authoritative references that establish this reality.Paul Niquette (talk) 08:10, 27 May 2017 (UTC)

Except that oscillation resonances are a real and long-recognized: Resonance.

Celestial bodies' orbits sometimes have resonances: Orbital resonance. These can cause celestial bodies to speed up and slow down relative to each other, with periodic reversals. The Solar System has several orbital resonances or near-resonances, and here are a few of them:
 * Jupiter-Saturn: 5:2
 * Jupiter's moons Io-Europa-Ganymede: 4:2:1
 * Saturn's moons Mimas-Tethys: 2:1
 * Saturn's moons Enceladus-Dione: 2:1
 * Saturn's moons Titan-Hyperion: 4:3

Tidal locking makes spin-orbit resonances. Such resonances are usually 1:1, as in the Moon and the Solar System's other large moons, but Mercury has a 3:2 spin-orbit resonance.

So it's well worth noting that all of TRAPPIST-1's known planets are in a resonance chain. Lpetrich (talk) 08:57, 28 May 2017 (UTC)

Surface Gravity
The most user friendly unit is m/s2. cgs, as stated is not a unit. Log g is also unhelpful for 2 reasons. The base of the log (eg ln or log10) is not stated. And it is not particularly helpful as, withough a calculator to hand, an intuitive comparison to the gravity of earth is not possible for the not physicist reader. — Preceding unsigned comment added by 2A02:C7F:C409:DA00:55EC:401D:D824:6615 (talk) 22:52, 8 May 2017 (UTC)


 * In astrophysics, log(g) is the standard when expressing surface gravity on stars, and is typically expressed without units (log10 and cgs units are assumed; see e.g. this entry).Dab8fz (talk) 21:51, 30 May 2017 (UTC)


 * Ow that is a frustratingly obscure way to present the data. And how exactly do we put the units explicitly, if we want to have a brief statement?  I would want to write that log10(980.665 cm/s2) = 2.992 + log10cm - 2 log10s, but I must admit that AFAIK no one else on God's green Earth would write it that way (maybe they see it my way on TRAPPIST-1...) .  So put me down as a vote for the simple-minded way. Wnt (talk) 23:25, 2 June 2017 (UTC)

Age
On the Age of the TRAPPIST-1 System

We collate empirical age constraints based on the color-absolute magnitude diagram, average density, lithium absorption, surface gravity features, metallicity, kinematics, rotation, and magnetic activity; and conclude that TRAPPIST-1 is a transitional thin/thick disk star with an age of 7.6±2.2 Gyr. Agmartin (talk) 17:27, 8 June 2017 (UTC)

Update the mass and radius?
As shown in] Van Grootel et el, the mass of TRAPPIST 1 is 0.089 Solar Masses or 93 Jupiter Masses (1,047x0.089=93.183), up from the 84 Jupiter Masses in the Stellar Characteristics section. Furthermore it's updated radius is 'Roughly 12%' that of the Sun, compared to the roughly 11% in that section.

In addition, based on the plots from the lifespan graph from Adems et el, a 0.089 mass Red Dwarf would remain on the Main Sequence for around 8.5 trillion years, as it is between the 0.1 solar mass 6.2 Trillion and the 0.08 Solar Mass 11 Trillion. Prussia1231 (talk) 06:50, 9 April 2018 (UTC)

Temperature Notes missing.
Other articles have temperature formulas in the *Notes* section, why is this missing the temperatures for these planets??

Can someone who knows that temperatures are listed for other planets, and sometimes they are added in the using basic formulas and know data, with the formula being places in the *Notes* section, please add the temperatures for the planets to this article. 50.70.236.24 (talk) 01:56, 19 April 2018 (UTC)

TRAPPIST-1b Temperature

 * Temperature	(T) 391.8 ± 5.5 K (equilibrium) ≥1400 K (atmosphere) 750-1500 K (surface)

TRAPPIST-1c Temperature

 * Temperature	(T) 334.8 ± 4.7 K (61.65 ± 4.70 °C; 142.97 ± 8.46 °F) (equilibrium) (for a null albedo)

TRAPPIST-1d Temperature

 * Temperature	(T)	282.1 ± 4.0 K (8.95 ± 4.00 °C; 48.11 ± 7.20 °F) (for a null albedo)

TRAPPIST-1e Temperature

 * Temperature	(T)

TRAPPIST-1f Temperature

 * Temperature	(T)

TRAPPIST-1g Temperature

 * Temperature	(T)

TRAPPIST-1h Temperature

 * Temperature	(T)

Orphaned references in TRAPPIST-1
I check pages listed in Category:Pages with incorrect ref formatting to try to fix reference errors. One of the things I do is look for content for orphaned references in wikilinked articles. I have found content for some of TRAPPIST-1's orphans, the problem is that I found more than one version. I can't determine which (if any) is correct for this article, so I am asking for a sentient editor to look it over and copy the correct ref content into this article.

Reference named "Luger": From Extraterrestrial atmosphere: Extreme Water Loss and Abiotic O2 Buildup on Planets Throughout the Habitable Zones of M Dwarfs. Luger R. and Barnes R. Astrobiology. 14 February 2015, Vol 15, Issue 2; pages 119-143. DOI: 10.1089/ast.2014.1231 From TRAPPIST-1h:  

I apologize if any of the above are effectively identical; I am just a simple computer program, so I can't determine whether minor differences are significant or not. AnomieBOT ⚡ 20:20, 20 April 2018 (UTC)

Lead problems
The lead was doing a decent job for specialized readers, but ignoring the needs of those who mostly know a few constellations when they see them. I double-majored in physics and math, ages ago, but in my mind i was intersecting our galaxy with a truncated cone whose vertex is at our sun; the only distance i know in light-years is from here to where the Big Bang is just starting. I think most of our readers need and deserve an article with at least a lead section that is seriously adjusted for the benefit of the layperson. --Jerzy•t 09:22, 29 June 2018 (UTC)

Image
Although this image is quite dull compared to the artist impressions, it is the only image of TRAPPIST-1 recently released by NASA. The image can be found here: https://www.nasa.gov/image-feature/ames/kepler-s-final-image-shows-a-galaxy-full-of-possibilities Or the direct image link: https://www.nasa.gov/sites/default/files/thumbnails/image/trappist1-final-hour-long-cadence.gif — Preceding unsigned comment added by 107.210.28.247 (talk) 00:02, 7 February 2019 (UTC)

Resolved. Nrco0e (talk) 06:52, 23 February 2019 (UTC)

Planets d, e and f are not tidally locked
Tidal locking had been assumed for all seven planets. This assumption is also underlying many of the studies regarding habitability. However, a new study shows that the mutual interactions between the planets prevents at least planets d, e and f (the ones located in the habitable zone) from ever getting locked. Depending on the strength of the perturbations, the planets may be fully rotating. Their rotation states are chaotic, with axes and rotation periods evolving on time scales of millennia. Renerpho (talk) 22:06, 29 May 2019 (UTC)

Refined masses, radii, etc.
On arxiv: Refining the transit timing and photometric analysis of TRAPPIST-1: Masses, radii, densities, dynamics, and ephemerides Agmartin (talk) 20:10, 5 October 2020 (UTC)

That work has an interesting conundrum. The planets' masses jump by sizable amounts from their previous published values, the values in the current version of the article. How should we make a note of this in the article?

By comparison, the radius values don't vary nearly as much.

We may also want to note what Agol et al. conclude about the compositions of these planets. Their numbers are consistent with all seven of them having very similar compositions, like their having a little less iron than in the Solar System. Lpetrich (talk) 00:14, 6 October 2020 (UTC)
 * Presumably this explains why this illustration doesn't match the current text of the article (which claims, for example, that d is denser than the Earth). Anyway, the paper's published now, so there seems to be no reason not to update the article accordingly. 88.145.190.231 (talk)
 * After looking at the article again I see that the table at the top of the section is up to date, but the text isn't - it presents the information from 2018 as if it were current. Someone needs to fix this. 88.145.190.231 (talk) 17:05, 25 June 2021 (UTC)

Trappist-1's planets
Considering how the page about Trappist-1 now includes MORE information about the planets than their individual articles themselves, or at least some information (such as Tidal effects) not found in those, wouldn't it make more sense to shorten this article (specifically the Planets list) in favor of expanding the individual articles about Trappist-1b,c,d,e,f,g and h ? Sir Proxima Centauri (talk) 20:16, 28 November 2021 (UTC)
 * Why not both? I think it's really useful to have everything here, it gives the whole picture without any need of jumping between the pages. But individual articles can of course be expanded, if needed. Artem.G (talk) 20:42, 28 November 2021 (UTC)
 * The existence of the subarticles is the reason why the information for each planet in the list is so condensed already. I am not sure that it'd be a good idea to condense it even more. Jo-Jo Eumerus (talk) 22:56, 28 November 2021 (UTC)

How orbital resonances work
Original: The resonance increases the planets' pull on the host star and the resulting changes in TRAPPIST-1 are more easily recognized through observations, which makes studies of the system easier such as measuring the planets' mass when other techniques are not available.

I attempted to fix it with The resonances make the planets go alternately ahead and behind in their orbits over the resonance periods, in greater amounts than simple estimates indicate, something which makes studies of the system easier such as measuring the planets' masses when other techniques are not available. I tried to make a short summary of the explanation in Orbital resonance. Resonances between planets do *not* increase the gravitational pull on their stars. Instead, they make the planets advance and retreat in their orbits over several orbit times. This advancing and retreating is cumulative, and is thus much larger than perturbations over an orbit period.

It got reverted to the mistaken original.

Lpetrich (talk) 01:34, 7 December 2021 (UTC)
 * I've reinstated it. Seems like I confused that information with another piece that couldn't stay. Jo-Jo Eumerus (talk) 09:24, 7 December 2021 (UTC)

"Roche lobe" vs. "Roche limit"
History of edits:

Original: in such a densely packed planetary system as they would tend to be either torn apart by their planet's gravity after crossing the Roche lobe or stripped from the planet.

I redid it because the Roche lobe is very different from the Roche limit. The boundary of the Roche lobe is the outer limit of being bound, and it is close to the "Roche sphere" or Hill sphere, while the Roche limit is the inner limit of staying in one piece. A moon's orbit will be stable if it is between the Roche limit distance, where the planet pulls the moon apart, and some fraction of the Hill sphere distance, where the star's gravity makes the moon escape. This is a narrow range for the TRAPPIST-1 planets, especially the inner planets. It was reverted to original.

I came up with this version, complete with keeping an appropriate reference: in such a densely packed planetary system as they would tend to be either torn apart by their planet's gravity after going inside the Roche limit or stripped from the planet after going outside the Hill sphere. That one was reverted also, despite having a source that mentions both the Roche limit and the Hill sphere, though as the Hill radius.

Lpetrich (talk) 01:25, 7 December 2021 (UTC)
 * Hrm, I don't think the second edit was actually reverted? Jo-Jo Eumerus (talk) 09:22, 12 December 2021 (UTC)

You should look at it again. It's still the original edit, one that uses "Roche lobe", instead of distinguishing between the Roche limit and the Hill sphere. Kane's paper uses "Hill radius", and we could use Hill radius -- Hill radius. Lpetrich (talk) 19:45, 12 December 2021 (UTC)
 * I think it's probably better if we stick with using "Roche" for the sphere around a planet where its tides rip a moon apart and "Hill" for the sphere around a planet where it can hold on moons. What say you? Jo-Jo Eumerus (talk) 20:03, 12 December 2021 (UTC)
 * Providing a third opinion: I agree with "Roche limit" for the sphere around a planet where its tides rip a moon apart and "Hill" for the sphere around a planet where it can hold on moons. ParticipantObserver (talk) 16:32, 13 December 2021 (UTC)

Thanx for all the help. I think I'll go ahead and make that edit. 17:14, 13 December 2021 (UTC) — Preceding unsigned comment added by Lpetrich (talk • contribs)

Terrestrial planets
This article says "As of 2017, the planets of TRAPPIST-1 are the closest likely terrestrial planets that transit their host star." The footnote next to "terrestrial" says "A terrestrial planet is a planet that is likely to resemble Earth." While technically true, this is misleading - a terrestrial planet resembles Earth only in having a rocky composition, without implying anything about habitability. I would correct the footnote myself, but actually the whole sentence is wrong - there are closer transiting planets that are likely terrestrial, such as HD 219134 b and c. So probably the whole sentence should be removed. SevenSpheresCelestia (talk) 19:32, 25 December 2021 (UTC)
 * Done. Jo-Jo Eumerus (talk) 20:20, 25 December 2021 (UTC)

Travel time to TRAPPIST-1
Sir Proxima Centauri, please give a source if you claim that a spacecraft - any spacecraft - would need "millions of years" before reaching TRAPPIST-1. We cannot have content cited to a source that does not support the claims per WP:OR. Jo-Jo Eumerus (talk) 21:45, 9 January 2022 (UTC)

https://www.space.com/35796-trappist-1-alien-planets-travel-time.html So, this article claims that Voyager 1 would need almost 700,000 years with its speed to reach Trappist-1. New Horizons, with its current speed, would need about 800,00 years to travel the 39 light years, and the Space Shuttle would already need 1.5 million years.

https://www.wbur.org/cognoscenti/2017/03/02/trappist-1-40-light-years-away-joelle-renstrom This other article also mentions a space shuttle travel time to Trappist-1 of 1.49 million years, and that New Horizons would need 80,000 years to reach Alpha Centauri (4.3 light years). As Trappist-1 is 39 light years away, this again implies that the probe would need about 800,000 years to reach Trappist-1

http://owlconnected.com/archives/long-take-reach-trappist-1 Again, this source gives a travel time of 1.5 million years for humans using the Space Shuttle and 815,000 years for New Horizons.

https://voyager.jpl.nasa.gov/mission/did-you-know/ NASA claims that the Voyager probes will pass the Oort cloud (2 light years, half the current distance to Proxima Centauri) in almost 40,000 years. Trappist-1, at about 20× the distance would therefore be reached by the Voyagers in more than 700,000 years.

The previous claim of "more than 100,000 years" to reach Trappist-1 therefore reads as specific as "New Horizons needs more than a year to reach Pluto". With these figures, coming from our fastest interstellar probes, we should therefore mention that the current travel time to Trappist-1 will not be a single, but several hundred thousands, if not millions of years. Sir Proxima Centauri (talk) 15:06, 10 January 2022 (UTC)
 * Most of these say it's less than one million years, though. So the current formulation hundreds of thousands of years seems more accurate, unless we want to add a "many". Jo-Jo Eumerus (talk) 15:38, 10 January 2022 (UTC)

Well, the numbers of 700,000-800,000 years are all referencing the Voyager probes and New Horizons. Pioneer 10 & 11 are even slover than those, so they, and especially any other current non-interstellar spacecraft may be approaching a time closer to a million or more years. It would only make sense to add the mention of "perhaps even millions of years" if we consider all of that. Sir Proxima Centauri (talk) 15:52, 10 January 2022 (UTC)
 * I am concerned that we are bordering on WP:SYNTH if we use the travel times of probes that weren't discussed in the context of TRAPPIST-1, though. Besides, it's unlikely that future probes will be than the old ones, or at least so would I think. Jo-Jo Eumerus (talk) 16:46, 10 January 2022 (UTC)

How much WP:WEIGHT to give to...
...this study's inference that there may be atmospheres on the innermost TRAPPIST-1 planets? The inference is discussed at this source for example. And also where to discuss it - first sentence of the atmosphere section or the bullet point on a hydrogen atmosphere? Jo-Jo Eumerus (talk) 20:43, 23 January 2022 (UTC)

Ideas and questions on a future expansion
So, I've been thinking for a while about trying to bring this article up to FA status. Now unlike other articles I've brought from stub or redlink to FA this one is already fairly well-developed, so I am going to discuss a few things: Note that I am purposefully planning to do this before the launch of the James Webb Telescope; I want to split the work so that it's not too much at once. JoJo Eumerus mobile (main talk) 09:21, 27 October 2021 (UTC)
 * Currently the article does use references w/o indicating specific page numbers for particular claims. In my experience FA usually expects page numbers when the source is more than a few pages long. So a rewrite would imply adding lots of page numbers.
 * Partly as a corollary to the above, it's usually much easier to write new text from scratch & replace the current text from scratch than to add page numbers to already existing sourced text. I am not sure what people's considerations are on this.
 * It seems like astronomy articles often use databases as sources; is there a list of such sources that could/should be used?
 * Is there an established "best practice" on how to balance sources that rely on computer simulation with these that rely on observations?
 * Should topics like planetary atmospheres be discussed in a dedicated header, or per planet?
 * Well, this was rather ... silent. I've thus pressed ahead and put in a biggish rewrite. I've taken the liberty to put in a sfn format b/c the previous format did not have page numbers and many of the sources are too long to find a specific piece of information by scrolling. I know about WP:CITEVAR but I am interpreting If all or most of the citations in an article consist of bare URLs, or otherwise fail to provide needed bibliographic data – such as the name of the source, the title of the article or web page consulted, the author (if known), the publication date (if known), and the page numbers (where relevant) – then that would not count as a "consistent citation style" and can be changed freely to insert such data. The data provided should be sufficient to uniquely identify the source, allow readers to find it, and allow readers to initially evaluate a source without retrieving it. as allowing a change in citation format to allow page numbers. Jo-Jo Eumerus (talk) 17:12, 16 November 2021 (UTC)
 * Very much hoping the relevant page numbers are taken from the accessible eprint versions of the quoted published papers, and not from the versions published in journals that are often behind rather inaccessible paywalls. — Preceding unsigned comment added by 109.153.209.239 (talk • contribs)
 * Unfortunately I always used the pagenumbers of the URLs I used, which typically weren't the eprints. My understanding is/was that the citation needs to be based on the URL the editor used, not on a different URL. Jo-Jo Eumerus (talk) 10:23, 24 January 2022 (UTC)

Earth Similarity Index: Include or not
So, in light of this removal something that I was wondering about when I did my big page expansion is coming up again: Should we mention the Earth Similarity Index ranking of the TRAPPIST-1 systems or not? Initially I wasn't sure whether to mention any of these indexes because there are many of them and there is relatively little independent coverage of both. I was eventually convinced by the number of mentions of the ESI by various academic sources - even excluding preprints and self-published articles - that citing that index and only that one was appropriate. Jo-Jo Eumerus (talk) 12:45, 22 February 2022 (UTC)
 * Since the link in the deletion summary is broken: Wikipedia talk:WikiProject Astronomy/Archive 24 Jo-Jo Eumerus (talk) 12:47, 22 February 2022 (UTC)
 * Thanks for the usertalk notification! Unfortunately, the list you provide is to a lot of subpar journals and some that are appear to be unduly advertising for ESI as a way to describe things. Google Scholar, it turns out, includes a lot of problematic content when it comes to astrophysics. A much better resource is the Astrophysics Data System (ADS) where you can see the single result here:.
 * As we discussed o those many years ago, the problem with ESI is that it is not validated and time has not been kind to it since then. ESI has ultimately ended up being just one person's opinion. There are other measures that have more utility and interest for the scientific community than ESI, and even then many of those are highly criticized as misleading "ordering" (I recently had a discussion with other astronomers on Twitter about this paper: ). In short, I think the impulse to want to include an index or a ranking is one that is understandable coming from Wikipedia editors, but it just is not something that is reliably referenced. My advice is to stick to the broader discussions of habitability, planet comparisons, and astrobiological contexts and leave out the attempts to make factoid/listicle clickbait. Not that the latter was your intent, but unfortunately this is how it often gets regurgitated as people use Wikipedia. And since the best and most reliable sources on exoplanets don't do this (and there are more than a few sources that explicitly criticize such approaches), I say we follow their lead. jps (talk) 16:35, 22 February 2022 (UTC)


 * I agree with jps. The Earth Similarity Index hasn't received much support in the broad astrophysics community (fwiw, a quick search here revealed nothing about it), so its inclusion seems undue. JoJo Anthrax (talk) 00:43, 23 February 2022 (UTC)

Number one of TRAPPIST catalogue?
Is TRAPPIST-1 the first member of the TRAPPIST catalogue? In other words, is there a TRAPPIST-2, a TRAPPIST-3, TRAPPIST-4, TRAPPIST-5, etcetera...? DannyCaes (talk) 10:18, 29 April 2022 (UTC)
 * Not as far as I can tell. Jo-Jo Eumerus (talk) 10:45, 29 April 2022 (UTC)
 * Anyway, thanks! It's something I always want to know when I read about an astronomical object which has catalog number one (1). The same sort of question pops up when I read something about, for example, the galaxy known as Fath 703 in Libra. Where are the other Fath galaxies? (from 1 to 702, and from 704 to... ???). Another example: the binary star Kruger 60 in Cepheus. Where are numbers 1 to 59 and 61 to... ??? It is an interesting hobby, exploring astronomical catalogues, but... very confusing! DannyCaes (talk) 21:46, 1 May 2022 (UTC)

Gaia
Is there some reason the article uses ancient astrometry? Positions from 2002, proper motions from 2006. The parallax is at least from 2020 and there might be a case for keeping it, but ... Gaia DR3 is out and it's pretty good. Lithopsian (talk) 21:04, 17 June 2022 (UTC)
 * Bailer-Jones calculates the distances using Gaia EDR3 parallaxes (DR3 not yet published). It uses a statistical method that can produce different results from a simple inversion of the parallax, although for stars as close as this there is virtually no difference.  FWIW, the value given is $12.4 pc$, not bad.


 * Really only the fact that I don't keep up with astrometry databases. Feel free to update them. Jo-Jo Eumerus (talk) 18:41, 18 June 2022 (UTC)

"Considering many papers dating to the early 2000s describe certain planetary systems as the most numerous ones elsewhere, Kepler-90 doesn't really need additional clarification either"
Is it worth stating somewhere that Kepler-90 currently has the largest known planetary system? Jo-Jo Eumerus (talk) 14:10, 27 June 2022 (UTC)
 * At the moment, I don't quite see where it would fit in the main prose. If the article mentioned that TRAPPIST-1 is one of the systems with the most known planets, then Kepler-90 may be appropriate in a footnote as having the most of all (8). The See also section may be a nice compromise, however, since several other large exoplanet systems are mentioned. ComplexRational (talk) 16:21, 30 June 2022 (UTC)

Potentially a source to add
This one which proposes an outer solar system mission to observe this system. Jo-Jo Eumerus (talk) 08:58, 2 November 2022 (UTC)

First TRAPPIST-1 NIRISS data on MAST
Hello everybody. I have just discovered that the first NIRISS data for TRAPPIST-1 is now publicly available on MAST. I'm wondering if this is worthwhile to put in the article, and if anyone here knows how to interpret the data? Limitlez1 (talk) 20:52, 19 July 2022 (UTC)
 * Greetings. Wikipedia does not usually interpret datas by itself], we tend to wait until a reliable source has done that. I'd imagine we'll see publications this year using these data, which I'll be adding on Christmas. Jo-Jo Eumerus (talk) 10:24, 20 July 2022 (UTC)
 * @Limitlez1 Could you put a link to that data here on the talk page? Considering that the article currently contradicts itself (more about that later), it might be helpful to check the original data to check which part of the article is likely to be the correct part. Thanks. Dhrm77 (talk) 11:03, 3 November 2022 (UTC)

Inconsistency between Resonance and Orbital Periods of the planets in the system
Currently, the article lists these orbital periods for the 7 planets: Assuming that these numbers are correct, the best resonance ratio you can find would be: 210:131, 744:445, 449:298, 329:218, 326:243 and 269:177 between neighboring planet pairs. I suspect that these are incorrect because it would require a resonance cycle to be very large, which is probably unlikely for a dense system. Conversely, if the resonance ratios given in the next section (namely 8:5, 5:3, 3:2, 3:2, 4:3, and 3:2 between neighboring planet pairs) are correct, then in order for these resonance to fit the orbital period of each planet, we need to increase the tolerance on these orbits by a factor 2606.3 in the worst case, and 138.3 in the best case. That gives us this table: Now if we observe the tolerance given for the orbit of Trappist-1b, 0.000006 is about 0.5 second. And the tolerance for Trappist-1c is 1.5 seconds. I doubt that we were able to obtain that level of precision, from so far away, without monitoring the system for many years. So I have concerns about the accuracy of these numbers. Conversely, in order to fit the resonance in a very nice 8:5, 5:3, 3:2, 3:2, 4:3, and 3:2 ratios, we need the tolerance to be off by a factor of 2600, which is also hard to believe. The fact that to make these ratios fit, the error is positive on the first 4 planets, and negative on the last 3, and higher in the 2 extremes, by itself suggest that these ratios are unlikely to be correct. But there are other possibilities. If we assume that both the tolerance on the orbit measured and the given ratios are wrong (it is not uncommon for someone to make a mistake in numbers by a factor of 1000 or 100, just by placing a decimal separator at the wrong place), then we can come up with alternate solutions, such as the ones given in the following tables: For this first table, we only need to multiply the tolerances given by 15, and the numbers used in the ratios are now much smaller: For this first table, we only need to multiply the tolerances given by 169, and the numbers used in the ratios are again a little smaller: For this first table, we only need to multiply the tolerances given by 368, and the numbers used in the ratios are again a little smaller: For this last table, the tolerance needs to be 1288 times the tolerance given, much better than 2610, and only one ratio is different: I suspect that the fact that we have to significantly deviate from the measured orbital periods to obtain a system-resonance with ratios using small numbers, means that there is probably an 8th planet, much heavier and much farther from the star than the others, that is making the star wobble enough to cause the error in orbital period measurements. But I speculate. In any case, currently the article is contradicting itself, and that's not good. And I get it, we are only quoting some other people's papers, But we need to apply some discernment as well. Dhrm77 (talk) 13:29, 6 November 2022 (UTC)


 * Eh ... sorry, but this feels like a pile of original research to me. Besides, does this calculation include the margins of error of each timing? Jo-Jo Eumerus (talk) 14:24, 6 November 2022 (UTC)
 * I guess you could say that the second part is original research. But the first part is not: You can easily plug the numbers from the article into an excel spreadsheet and verify that the orbits given are not consistent with the resonance ratios given. And regarding the margins or error, see below. Dhrm77 (talk) 18:58, 6 November 2022 (UTC)
 * Do these calculations take into account orbital precession (which, among other things, causes natural slight variations in orbital period), corrections for sidereal period, and measurement uncertainty? These factors would result in an apparent small discrepancy in the measured periods and perfectly-in-resonance periods, and also, a stable resonance would correct itself but not be in a fixed perfect ratio each cycle.
 * Taking Neptune and Pluto as an example, we have a ratio of 247.94/164.79 ≈ 1.505, which is obviously not 3/2. Additionally, Neptune completes an orbit on average every 164.79 years, subject to a variability of around ±0.1 years, and Pluto pretty certainly does the same, yet we still don't reach exactly 3/2 (1.504–1.507). Therefore, precession and adjustment for sidereal vs. synodic period must be considered to arrive at the ratio of 3/2, as tolerances alone don't do it. Yet there is a clear consensus in the literature that Neptune and Pluto are in a stable long-term 3:2 resonance. Applying these same calculations to the Solar System would allow one to claim that bodies are not in resonance, whereas there is plenty of evidence that they are.
 * Likewise, unless a hypothetical eighth planet is the predominant theory in the literature (AFAIK it isn't), I would very strongly advise against proposing it in the article, as it would indeed constitute original research. Complex / Rational  16:37, 6 November 2022 (UTC)
 * @User talk:Jo-Jo Eumerus & @User talk:ComplexRational, all I am doing is:
 * 1) taking the numbers from this article and showing that there is a contradiction between 2 statements.
 * 2) and additionally offering an alternate solution to the idea that one of them is correct.
 * First, of course I am taking into consideration the margin or measurement uncertainty (what I call tolerance, above). Why would I say that you need to multiply that tolerance by a factor of 2607 to make the numbers fit, if I didn't take it into consideration?
 * Then, I don't know how an orbital precession can be evaluated for such a distant system. I assume that the measurements were obtained by averaging successive obstructions of the star by each planet. And, assuming there is no significant wobbling of the star, that should give us a good orbital period.
 * Now, the whole point of this post is to show that the orbital periods (including their uncertainty), and the given resonance ratios cannot be both true at the same time. One of them is necessarily wrong, or both. Let's take an example: the orbit of planet 'b' is given as 1.510826 ±0.000006, that means it would be a minimum of 1.510820 days, and a maximum of 1.510832 days. Likewise for planet 'c', 2.421937-0.000018 is 2.421919 days, and 2.421937+0.000018 is 2.421955 days. If you divide the minimal orbit of one by the maximum of the other, and vice versa, the range of ratios goes from 1.603036605 to 1.603073166. A ratio of 8:5 = 1.6 doesn't fit within these 2 limits. So we have a choice, find a integer ratio that fits between these 2 values, or increase the tolerance (margin or uncertainty) so that a integer ratio will fit. And this is exactly what I did.
 * Actually, what I did was a little more complex because I needed to make sure that all the resonance ratios between all the planets would work at the same time, not just 2 by 2.
 * Now, the biggest clue that the given ratios (8:5, 5:3, 3:2, 3:2, 4:3, and 3:2) are wrong is if you look at the first and last planets. From these numbers, if you calculate their orbital ratio, you get a ratio of 12:1. But if you divide their orbit periods, you get numbers between 12.42537357 and 12.42575555, which is a lot closer to 25:2 than 24:2 (or 12:1). A 12:1 ratio has an error of 3.5%, which is huge considering the alleged precision of the orbital periods given.
 * The other point of this post is that we shouldn't just quote someone else's papers without any discernment, especially when they contradict each other.
 * The second part of my post is to offer possible alternatives to the numbers given:
 * 1) First, the orbital resonance given just do not work for the orbit measured.
 * 2) the tolerance (or margin) given seems unlikely (precisions of 0.5 second or 1.5 seconds from that far away seems unlikely).
 * So my opinion is that both the tolerance given and the resonance ratios are wrong. My program spit out 24 possible resonance scenarios. I just listed the 4 most likely (or characteristic) to actually be.
 * Also, I'm not sure that a comparison with our own system (Neptune, Pluto, etc...) is valid, since we are observing the system within the same system, and the technique to measure the orbital period is very different. Dhrm77 (talk) 18:51, 6 November 2022 (UTC)
 * This is still too far into WP:OR territory. The article these orbital parameters are from does consider some of these points and still concludes that it's a resonance. Other sources do so as well. Jo-Jo Eumerus (talk) 09:32, 7 November 2022 (UTC)

Planet masses: qualified help needed
Hello! I've noticed some inconsistencies between this page and the individual pages for the 7 planets of the TRAPPIST-1 system, and although I believe this should be corrected I don't think I'm qualified to select the most accurate source.

If we look at the table in that section and pick the first planet TRAPPIST-1b, the table quotes its mass as "1.3771±0.0593 M🜨". But on the dedicated page for TRAPPIST-1b, the mass is listed as "1.017 +0.154/−0.143 M🜨" – meaning the ranges of these two estimates don't even overlap.

The figures for all planets have similar inconsistencies.

This is because the numbers in the table come from this January 2021 paper ("Agol 2021") where they can be found in Table 2 on page 13, whereas the value on the TRAPPIST-1b page comes from this May 2018 paper ("Grimm 2018"). In fact the 2021 paper does provide a table where they compare their estimates to those from Grimm 2018 in Table 3 on page 13, and discusses previous estimates and their uncertainties.

This is what I think should be done:


 * 1) A choice should be made to select an appropriate source for this information, be it one of these two papers or even another one.
 * 2) The TRAPPIST-1 page should be updated if this source is not Agol 2021.
 * 3) The individual pages of the 7 planets should be updated with information consistent with the TRAPPIST-1 page.
 * 4) A similar review and possible correction should be undertaken for other parameters, such as radius, mean density, temperature, and orbital parameters, etc.

Needed: someone who has the necessary domain knowledge should suggest a source to rely on. Even simply making a suggestion here and providing the reasoning behind it would go a long way; I'm sure other Wikipedians could then make the actual edits. I am not suggesting that a single person do this all by themselves. Nffwp (talk) 22:41, 17 November 2022 (UTC)
 * I think the best option is to update the planet pages with the data from Agol 2021. Jo-Jo Eumerus (talk) 09:32, 18 November 2022 (UTC)

Addition to lead
This was just added to the article's lead: Over 2022, the James Webb Space Telescope has been observing the TRAPPIST-1 system, and taken spectra of the planets, which should reveal whether they host atmospheres and liquid water. I think it's a bit undue to give one particular mission an entire lead paragraph, seeing as the lead section only covers the broad strokes so far - especially since it hasn't actually discovered anything yet. Jo-Jo Eumerus (talk) 09:30, 21 November 2022 (UTC)

Which planets are within the habitable zone
Regarding this edit, the article currently omits detailed discussion on which planet is within the habitable zone and which not because it's an evolving field without a scientific consensus yet that is probably better discussed at the articles of the individual planets. Also, the source given isn't really a good source for such a claim. Jo-Jo Eumerus (talk) 10:21, 18 December 2022 (UTC)
 * The article does clearly describe uncertainty regarding the habitable zone, though the linked edit introduces no more detail than was already present (e.g., the claim TRAPPIST-1c is not within the habitable zone, cited to the same source, was there before). I agree, however, that trying to go into too much detail may introduce speculation or undue weight, and perhaps a more recent source should be used to cross-reference (or challenge) this statement.
 * And we might also get significant information soon from JWST!  Complex / Rational  21:43, 18 December 2022 (UTC)
 * Aye, which is why I kind of hope to bring it up to FA status before then. I've rewritten the addition a little, mostly to keep related information together and for text-source integrity reasons. Jo-Jo Eumerus (talk) 09:47, 19 December 2022 (UTC)

Third attempt on prose
So, as with FAC1 FAC2 failed due to concerns about the prose quality and in clarity. I've done part of my annual article expansion and actioned some of the issues (I note though that in some cases, there'd be tradeoffs), but I think I'll need help with the prose before another attempt. Jo-Jo Eumerus (talk) 14:08, 1 November 2022 (UTC)


 * Unfortunately I don't think i'll be able to help with this article. (t &#183; c)  buidhe  09:25, 2 November 2022 (UTC)
 * Nobody else interested? :( Jo-Jo Eumerus (talk) 07:41, 4 November 2022 (UTC)
 * I'm a bit busy IRL at the moment, though I can give the article another in-depth look in a couple of weeks. Complex / Rational  16:18, 6 November 2022 (UTC)
 * Any update, ? Jo-Jo Eumerus (talk) 17:07, 5 December 2022 (UTC)
 * Still very busy IRL for another week, then I can take a closer look at the article. Complex / Rational  18:29, 5 December 2022 (UTC)
 * and, are you perhaps interested? Since you provided the most rigorous critique of the prose in the last FAC, I was wondering if you had advice on how to make it better. Jo-Jo Eumerus (talk) 11:25, 20 December 2022 (UTC)
 * I am keen - I used to do that sort of thing quite a bit - but I don't think that RL and other Wiki-commitments will permit. I am struggling to even keep up with responses to my current FAC. It may be worth checking with me again in a month or so, if the article's situation is unchanged. Gog the Mild (talk) 15:58, 20 December 2022 (UTC)
 * any updates? Jo-Jo Eumerus (talk) 12:47, 13 January 2023 (UTC)
 * , not right now, but I con't mind if you check with me every couple of weeks until you catch me at a slack moment. (I wish!) Gog the Mild (talk) 12:49, 13 January 2023 (UTC)
 * Let's see if this works...yes, I know I haven't been very active lately, myself. Jo-Jo Eumerus (talk) 15:13, 26 January 2023 (UTC)
 * I don't anticipate having significant free time for a while, so I can't make any commitment to reviewing. Feel free to ping me for more specific questions, though. Complex / Rational  16:25, 26 January 2023 (UTC)

Distance from earth
Most of the catalogues list a distance of Trappist-1 at 12.1 parsec (39.46 ly). But the article lists 12.47 parsecs (40.66 ly). I couldn't find a reliable source to confirm that distance, and I'm not sure where it comes from. It might comes from a journal article from 2020 that I don't have access to. Could you look into it? Thanks. Dhrm77 (talk) 16:19, 9 March 2023 (UTC)
 * I've checked it recently as part of the good article review. It's from the GAIA DR3 parallax (80.2123 mas, so distance = 1/0.0802123 = 12.47 pc), which is pretty recent. Robminchin (talk) 16:40, 9 March 2023 (UTC)