Talk:Epsilon Eridani/Archive 2

Wrong coordinates near the title
This page is displaying wrong coordinates under the title, sign of star declination reversed.

Displayed coordinates near link (Coordinates): 03h 32m 55.8442s, +09° 27′ 29.744

declination should be -09° 27′ 29.744

Dont know where to fix. Maaf (talk) — Preceding undated comment added 01:23, 28 April 2014 (UTC)

Merge from Epsilon Eridani c
I would like to suggest that Epsilon Eridani c is merged into this article. Previous precedent is that unconfirmed exoplanet candidates such as Epsilon Eridani c are not worthy of their own articles. The majority of the content at Epsilon Eridani c is in this article already anyway. Icalanise (talk) 23:26, 4 April 2011 (UTC)
 * I'm reluctant to support this based on format issues, primarily because the large infobox on this article would clutter up the content on the Epsilon Eridani article too much.&mdash;RJH (talk) 15:25, 5 April 2011 (UTC)
 * Personally I'm not so sure we really need to transfer the infobox over. Star details are already covered in the star infobox, the discovery information can be covered in the text, the alternate designations are mostly unused anyway so can probably be dropped. That essentially leaves the orbital elements and physical characteristics, the main ones of which are already summarised in the planetary system infobox anyway. Icalanise (talk) 17:24, 5 April 2011 (UTC)
 * Okay, in that case I "support". Thanks. Regards, RJH (talk) 19:28, 5 April 2011 (UTC)

I've attempted to merge the significant material that was cited on the Epsilon Eridani c article, and so removed the merge tag. (Note that this tag was holding up promotion of the Epsilon Eridani FAC.) I'm opposed to adding the unsourced content unless suitable citations can be found. Sorry.

The following entry appeared notable but lacked a suitable citation:
 * Epsilon Eridani c would be the first confirmed Jovian planet with an insolation similar to that of Neptune.

If a cite can be found, I think it would be an interesting addition to this article. For historical reference, here is a link to the unmerged article.&mdash;RJH (talk) 18:14, 10 April 2011 (UTC)
 * Sorry about holding up the FAC, was going to give it a week from my suggestion before merging but I guess it's good now. As for this statement about insolation, I'm not sure how relevant this is any more. For example HR 8799 b is a Jovian-type planet, it receives a similar insolation to Neptune and it is confirmed while Epsilon Eridani c still languishes in unconfirmed status. Icalanise (talk) 18:45, 10 April 2011 (UTC)
 * No worries. I also wasn't aware that it would be an issue. Thank you for checking.&mdash;RJH (talk) 19:51, 10 April 2011 (UTC)

FAC issues
Two points came out of the FAC that I think need to be addressed with this article: Regards, RJH (talk) 16:50, 13 April 2011 (UTC)
 * 1) At an earlier time, the section describing the debris disk was placed before the section about the planets because the former is confirmed information that was used to deduce the presence of the candidate planet(s). This was reversed by an editor, which caused a significant amount of rework in order to fix the flow. Two reviewers recommended restoring the original order.
 * 2) The Reidemeister et al. (2011) paper contradicts the earlier work that proposed the presence of two asteroid belts plus an outer Kuiper belt analog. This work needs to be consolidated into the article, which may thus require the presentation of two or more distinct models. The debris disk section may need a rewrite.


 * Regarding the order of sections, one of the articles I did a lot of work on to expand coverage on was Beta Pictoris. In this article the debris disc section comes before the planetary system, which matches the historical order of the discoveries: the debris disc was discovered before the planet. Doing something similar here might also help keep the discovery history in a reasonable order too. Icalanise (talk) 22:27, 13 April 2011 (UTC)
 * I've made some changes to the article in an attempt to implement these points. Also, the Reidemeister et al. (2011) paper mentioned several other studies underway that may provide further insight. It will be interesting to see what comes out of those investigations. Thank you. Regards, RJH (talk) 14:39, 24 April 2011 (UTC)

The Sun from Epsilon Eridani
The following paragraph was added to the lead by an anonymous editor:


 * The constellation Eridanus would be a little like the one observed by us, but would have a > sign and would overlap the constellation Horologium. The sun observed from there would be a 4.83 magnitude yellow star in the constellation Serpens Caput, next to Delta Serpentis.

There are a few concerns: it doesn't belong in the lead per WP:LEAD, it is using first person pronouns (see WP:FIRSTPERSON), the ">" sign is a vague personal opinion, it does not list the Sun's coordinates and it is unsourced. For these reasons I moved the entry here for discussion. Thank you. Regards, RJH (talk) 14:43, 26 April 2011 (UTC)

Expert review
Hi all. I asked a colleague at work - Iain McDonald, who works on exoplanets - to review the article. Here's the comments that he came back with:


 * One major issue stands out: the fact that planet b is now widely regarded as confirmed by most authorities (specifically exoplanet encylopediae such as exoplanets.eu). This affects the introduction (para. 2) and the section "Planetary System".
 * Done.


 * The table in "Planetary System" gives the most reliable figures I can find, however, the original reference for planets b and c comes from [78] (Benedict et al. 2006). This provided astrometric and radial velocity confirmation of eps Eri b and is the original citation for the purported planet c. This would replace reference [18] in this table. Reference [68] may also be replaced with the original reference, [19] (Backman et al. 2009).
 * Done.


 * Backman do cite Benedict et al., noting that they the planet is "possibly confirmed astromictrically" by them, but I believe this stance is overly cautious, and I think most people agree.


 * Regarding the last sentence in para. 2, reference [19] is incorrect for the last sentence. This does not discuss this in any detail. Regarding the above, the sentence is now not true, though magnetic activity does still limit the sensitivity of radial velocity measurements. The original reference is Marcy et al. (unpublished) at http://exoplanets.org/esp/epseri/epseri.shtml . Note, however, that this was last updated in 2002, and a lot has changed since then... hopefully including Geoff Marcy's stance!
 * I tweaked the wording. I wasn't really certain whether other reviewers would regard the Exoplanets article as a reliable source, so I added it to the External links section.


 * Observing history, para. 2: while a heliometer was originally a Sun-observing instrument, it appears from reference [29] that this specific heliometer was not designed for solar observations, but was merely a device for measuring the distance between two stars accurately. A viewable location for reference [29] is: http://www.archive.org/details/heliometerobserv00gillrich
 * Done.


 * Circumstellar discoveries. Generally this repeats a lot of the information in the later section "Dust disc". The two sections may be better off merged, so I have not given detailed comments here. Additional information that is not mentioned is that reference [19] could also be used here to give more up-to-date data. They suggest up to *three* planets are needed to explain the three belts listed in the table.
 * The two sections have since been re-ordered. The Backman et al. 2008 references is being used to say, "The structure of the belts and the dust disk suggests that more than two planets in the Epsilon Eridani system are needed to maintain this configuration." Effectively saying there may be at least three.


 * Properties, para. 2: stellar classification and metallicity determinations are all carried out from the line-forming region in the chromosphere. Since epsilon Eridani has a convective atmosphere, there is no reason why the chromospheric iron abundance (or that any other metal) should be different from the bulk atmospheric content. This last sentence is in need of revision.
 * I think the Gai et al (2008) paper suggests that the metals have been diffused below the convection zone. But I'm not sure why this particular star would be unique in this respect. I found no other source that attempted to explain the discrepancy between the age and metallicity. Should I pull it out? RJH (talk)


 * Magnetic activity, para. 1: it might be good to compare with the Solar value of 50-400 nT (from the "Sun" page).
 * Done.


 * Planetary system:
 * eps Eri b:
 * Para. 1: should the uncertainty information here be included in the table?
 * Done.


 * Para. 2: the description of the radial velocity technique does not mention that the cited value of 1.55 MJup [78] also comes from parallax measurements which fix the orbital inclination.
 * I'm not quite sure how best to address this one. Yes the Benedict et al. (2006) explains how the inclination is derived, but it seems as if trying to explain this technique to the reader would overly complicate the article. Any suggestions?

Hope that these comments are useful despite the FAC being withdraw. Thanks. Mike Peel (talk) 13:07, 27 April 2011 (UTC)
 * Thank you. Yes they are helpful. Regards, RJH (talk) 14:19, 27 April 2011 (UTC)


 * That's interesting, especially since I know and have worked with Iain! Modest Genius talk 18:07, 27 April 2011 (UTC)
 * Per being "widely regarded as confirmed by most authorities" in the first paragraph, I think this conclusion is readily inferred from looking at many of the sources. However, the difficulty comes in trying to cite an opinion of this nature. It usually requires an authoritative source (in a journal or whatever) that can speak for the collective astronomical community.&mdash;RJH (talk) 21:25, 27 April 2011 (UTC)

Here are the original ref. numbers referred to above:
 * [18] = Schneider
 * [19] = Backman et al. 2008
 * [29] = Gill 1893
 * [68] = Brogi et al. 2009
 * [78] = Benedict et al. 2006

Regarded as confirmed?
I took a look at what several recent papers had to say about Epsilon Eridani b: About half of the papers hedge their bets a little.&mdash;RJH (talk) 22:49, 6 May 2011 (UTC)
 * Benedict et al. (2006) - most likely explanation for the observed RV variations
 * Backman et al (2008) - tentative detection, possibly confirmed
 * Heinze et al. (2008) - detection of a closer in planet
 * Janson et al (2008) - exoplanet candidates reported/inferred
 * Brogi et al (2009) - planet ... was discovered
 * Reidemeister et al (2011) - orbited by a radial velocity planet
 * The general impression I get from the literature is that it is fairly sure that a planet with roughly the given orbital period exists, but beyond that the parameters (e.g. orbital eccentricity) are highly uncertain. Of course backing this up with reliable sources is another matter... Icalanise (talk) 02:12, 7 May 2011 (UTC)
 * Okay. What I thought I might do then is insert a sentence in the text (following: A comprehensive study ... long suspected but still unconfirmed) that says:
 * However, many astronomers believe this evidence is sufficiently compelling that they regard the discovery as confirmed.
 * then cite it with the multiple recent citations where this is clearly the case. Regards, RJH (talk) 15:36, 7 May 2011 (UTC)

Confirmation? Looking for astrometric signals below 20 m/s: A Jupiter-mass planet signature in ε Eri Agmartin (talk) 03:07, 6 July 2021 (UTC)

Circumstellar discoveries section redundant?

 * Except for the bit about another star, which was disproven, the entire 'Circumstellar discoveries' section is redundant. Is there some template or boilerplate for "star" articles that requires this section? If not, I suggest moving these bits to the more relevant subsection(s) of the 'Planetary system' section. – Ling.Nut 02:10, 2 June 2011 (UTC)
 * Yes there is some redundancy, but I'm not sure a merge is the best solution. I'd prefer that the 'Circumstellar discoveries' section state a brief, historical summary while the 'Planetary system' gives an expanded description from the current perspective. (Basically because the 'Circumstellar discoveries' section balances out the more speculative 'SETI' section.) Regards, RJH (talk) 14:30, 2 June 2011 (UTC)
 * Well, I'm just an English teacher. The cognitive load (read: odds of causing people to lose track of the thread of the information) increases every time you have this kind of a switchback, therefore readability decreases. It's best to keep things running in a single straight line, and place little summaries here and there (beginning and/or end of section) plus lotsa nice transition signals (words such as "however" etc.) to help people as they go. But having said all that, it's not like I'm gonna argue over it.  – Ling.Nut 15:04, 2 June 2011 (UTC)
 * I understand your perspective and I appreciate your observations. It would probably make sense to move a few of the key historical elements from the 'Planetary system' up to the 'Circumstellar discoveries' section so there is less overlap in subject matter. Thank you. Regards, RJH (talk) 15:25, 2 June 2011 (UTC)
 * Do whatever you think is best. I may copy edit a little more in the next few days. Or I may not. I dunno. Later – Ling.Nut 15:27, 2 June 2011 (UTC)

JAC image request
I sent a formalized request to the Joint Astronomy Centre asking if they could release their submillimetre wavelength image under licensing terms suitable for use on Wikipedia, but I never received a reply. Ergo, I don't believe we can use it even under fair use. Oh well. RJH (talk) 22:47, 13 September 2011 (UTC)


 * I'm a bit surprised you heard nothing at all; did you send it to outreach@jach.hawaii.edu ? They're very short staffed at present due to funding cuts and SCUBA2 commissioning. I'm not sure if that image is technically theirs though - copyright probably belongs to the astronomers who took the observations. Was worth asking though. Modest Genius talk 13:22, 5 October 2011 (UTC)
 * Yes, that's where I sent it. I'm sure they have more important things to do, so maybe they'll get to it at some point. Thank you. Regards, RJH (talk) 19:00, 5 October 2011 (UTC)

Interstellar mission target
I came across a paper which discusses the scientific motivations for targeting an interstellar mission (Project Icarus) towards this star, which might be of interest for the SETI section in this article. The paper is, see in particular section 4.1. Modest Genius talk 13:16, 5 October 2011 (UTC)
 * Thank you. Yes, Project Icarus is briefly mentioned in the article. I'm not sure that the paper adds much to what is already said in the article. Regards, RJH (talk) 19:03, 5 October 2011 (UTC)

HARPS paper
The following paper:

appears to raise some serious doubts about the validity of the suspected planet. But at least their best fit orbital model seems to lie in the ranges this article lists. Regards, RJH (talk) 21:09, 11 August 2012 (UTC)


 * Another HARPS paper, this time claiming an outright non-detection in the HARPS data:
 * 84.73.25.195 (talk) 01:27, 2 February 2013 (UTC)
 * 84.73.25.195 (talk) 01:27, 2 February 2013 (UTC)

Epsilon Eridani a?
With planets named b and c, the question arises: what happened to planet a? Kortoso (talk) 18:16, 27 July 2015 (UTC)
 * We don't use a for a planet since it is used by the star, like in the binary or multiple system. The star is always the primary object in the planetary system, and A is always used by the primary star in the multiple star systems. Primary means the #1 in importance or prominence and A is the first letter of the alphabet. Planet  Star  18:56, 27 July 2015 (UTC)
 * Yes, it's covered by this IAU page on the naming of exoplanets. (See the last two paragraphs of "Scientific designations".) Praemonitus (talk) 19:11, 27 July 2015 (UTC)

IAU recognizes eps Eri b???
Here IAU lists 20 systems for naming by the public, including eps Eri b! Does that imply it is officially recognozied as an exoplanet? Nergaal (talk) 23:03, 16 September 2015 (UTC)
 * I'm not sure that it matters whether they call it "official" or not. If they name it and the planet fails to exist, then it becomes another Vulcan. Even the latest Spitzer results failed to spot a planet&mdash;the best they can do is give some constraints to the planet's size. Praemonitus (talk) 17:53, 17 September 2015 (UTC)

Naming
I know that the IAU now recognizes Epsilon Eridani as Ran. Why isn't it stated as such? I saw it mentioned once, but there was no explanation. The person who submitted the name is James Ott, age 14. It didn't take much research for me to find it, so I don't see why it's not shown on the page. Here are the sources, if needed.

http://nameexoworlds.iau.org/names

http://www.spokesman.com/stories/2016/jan/14/mountainside-wins-competition-to-name-planet-star/ — Preceding unsigned comment added by OtterJam (talk • contribs) 23:50, 12 May 2016 (UTC)
 * Per WP:COMMONNAME, "Wikipedia generally prefers the name that is most commonly used". Ran may become so in the future, but for now it's not widely used. Praemonitus (talk) 17:14, 13 May 2016 (UTC)

Thank you, but that doesn't tell me why there isn't an explanation about how it has recently been renamed in the first public naming of planets. — Preceding unsigned comment added by OtterJam (talk • contribs) 00:16, 14 May 2016 (UTC)


 * Ran is in the list of names in the article. Lithopsian (talk) 18:55, 13 May 2016 (UTC)


 * There is an explanation here, in the final paragraph of the section. Praemonitus (talk) 03:47, 15 May 2016 (UTC)

External links modified
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WP:ENGVAR
Per this old revision and MOS:RETAIN I tagged this article as being written in British English. --John (talk) 21:09, 14 February 2017 (UTC)