Talk:Epsilon Eridani/Archive 1

Epsilon Eridani c?
I moved this claim from Epsilon Eridani here to Talk:Epsilon Eridani:
 * There may also be a second planet Epsilon Eridani c with about 3-5 times Jupiter's mass orbiting in an elliptical orbit every 25 years or so.

I wonder if this is mixed up with the hypothetical planet epsilon Eridani c mass of 0.1 Jup and 40 AU? As c is unconfirmed it doesn't seem to belong in the article. (I put the now struck-through Epsilon Eridani c earlier before checking the parameters) -Wikibob | Talk 20:29, 2005 Mar 25 (UTC)
 * Is this on the list of hypothetical planets? 132.205.15.43 15:26, 26 Apr 2005 (UTC)

Third closest star visible without a telescope? No, because 1) the Sun is a star visible without a telescope and 2) Alpha Centauri is closer and has TWO visible stars (according to the linked-to article).

It's either fourth of fifth, depending on how you count the Alpha Centauri system. Alpha Centauri A and B are too close for the naked eye to discern them apart; they appear as one star. Then comes Sirius, and then Epslilon Eridani. The Sun, of course, is first any way you count it. In any case, third is incorrect.


 * When somebody says N is the nth brightest star, the Sun is excluded. Sirius is the brightest star in the sky, not the second brightest. Alpha Centauri counts as one star which makes Epsilon Eridani third closest naked eye star.--Jyril 00:26, 22 December 2005 (UTC)

Mention that this star is the center of the Babylon 5 universe?
I'm a fan of the television series Babylon 5, and in episode "And now for a word" (transscript), we learn that the space station Babylon 5 orbits Epsilon Eridani. Wouldn't that be appropriate to add? Please let me know if it isn't appropriate. Pmorch 00:13, 30 August 2006 (UTC)
 * There's a link for an article about this star in fiction Ricnun 21:54, 12 October 2006 (UTC)

One of planets confirmed.
Here and here.

Yep, they did found Jupiter mass planet, EE is very young star, and has .8 mass of our own Sun, therefore habitable orbit is around 100-140 million km from the star.

Jupiter sized planet orbits EE at 200-800 million kilometer orbit, not sure if planet has any moons, and if these moons could support life, the fact is system is so young it is highly unlikely for life to have developed in EE system. I think system is still in process of forming, and with in next 10-15 years we'll have detailed map of the system, indicating exactly what is what. Mic of orion (talk) 00:36, 8 July 2008 (UTC)

http://hubblesite.org/newscenter/archive/releases/2006/32/image/a/format/xlarge_web/ http://hubblesite.org/newscenter/archive/releases/2006/32/image/b/format/xlarge_web/

Periapsis?
The source doesn't use the word "periapsis": The planet is so close it may be observable by Hubble and large ground-based telescopes in late 2007, when the planet makes its closest approach to Epsilon Eridani during its 6.9-year orbit It's possible that the source means the least angular distance as observed from Earth, not the least actual distance, which would be the periapsis.


 * One should read the preprint for details (and I will do so soon I hope). Icek 17:56, 7 December 2006 (UTC)

Reach
So, would we be able to equate the planet to Reach from the Halo series?

Al-Sadirah
I removed the following text:


 * Epsilon Eridani has no official proper name (being called only by its Bayer designation), although Arab settlers along the East African coast occasionally applied the name الصادرة Al-Sadirah "the Returning Ostriches" to the star nearly seven centuries ago.

Star Names by Richard Hinckley Allen assigns the Arabic name Al-Sadirah to a group of stars in Sagittarius. Hence a citation is needed to retain this paragraph in the article.&mdash;RJH (talk) 00:43, 20 July 2008 (UTC)

Minutes or seconds???
Changed the following text - the apparent width of the Moon is measured in arc-MINUTES, not arc-seconds.

At the star's estimated distance from the Earth, this astrosphere would span an angle of 42 arcseconds, which is wider than the Moon.[29]

Tonybaldacci (talk) 20:23, 19 August 2008 (UTC)
 * Correct. Thanks for the fix.&mdash;RJH (talk) 20:41, 19 August 2008 (UTC)

"Hubble confirmation"
I removed the following sentence: "In 2006, the existence of a planet with a 6.9 year orbit was confirmed using the Hubble Space Telescope," with its accompanying citation. Reasons: 1. The planet's discovery is already noted two sentences previously. 2. The 2006 article by Benedect and colleagues did not "confirm" the discovery, which unfortunately remains controversial. 3. The existence of the planet was not "confirmed using the HST." In fact, Benedict and colleagues used radial velocity data from many sources, including Hubble, to arrive at their improved parameters for planet b's orbit and mass. Unfortunately, again, their analysis did not turn out to be the last word on the subject. Dana Backman's recent article, mentioned in other citations -- and to be added to the reference list once I get to that section -- shows that the orbit derived by Benedict and colleagues is inconsistent with infrared observations of the dust rings orbiting Epsilon Eridani. So Hubble did not confirm anything.

Another way of putting this: if Benedict was right, then Backman is wrong (at least about the configuration of the two inner asteroid belts), and if Backman is right, then Benedict was wrong (at least about the precise configuration of planet b's orbit). Since the infrared data is a lot more detailed and reliable than the radial velocity data, the weight of evidence is on Backman's side.

In its present form, this article does not adequately capture the provisional nature of virtually all data on exoplanets, especially e Eri b. As much as we might like, we just can't (yet) construct neat little boxes that reliably provide fundamental parameters on exoplanets, the way we can with planets in the Solar System. Even though Epsilon Eridani is the nearest star to be proposed as the host of a planetary system, the available data on the planet(s) remains tentative.

For any interested parties, I'd be glad to provide links to 5 different sources published over the past 8 years, all highly respectable, that provide seriously conflicting results on the mass and eccentricity of planet b. A general trend can be seen:  sources whose authorship includes Marcy and Butler prefer smaller masses & eccentricities; sources whose authorship includes Hatzes prefer larger masses & eccentricities. These two sides managed to agree for the purposes of producing the discovery paper, published in 2000 and cited in this article, but they've been disagreeing ever since.

For the record, Backman explicitly prefers the Butler/Marcy values, as he and his colleagues state in their recent paper.Thuvan Dihn (talk) 02:50, 1 December 2008 (UTC)
 * Thanks. I agree that the "Planets" section of this article can be improved. Anything you can do along those lines would be appreciated.&mdash;RJH (talk) 17:22, 1 December 2008 (UTC)

Axial tilt.
"The axial tilt of this star remains uncertain, with estimates ranging from a low of 24° up to 72°." Relative to what? 68Kustom (talk) 14:27, 21 January 2009 (UTC)
 * The angle is relative to the line of sight between the observer and Epsilon Eridani. Spacepotato (talk) 20:36, 21 January 2009 (UTC)

Put a picture at the head of the article?
I feel like putting a picture of Epsilon Eridani at the head of the article, over the info box would be a good idea. Preferably an actual photo from an observatory or something similar, or a star map with epsilon eridani marked? Just my opinion for article aesthetics. --Pstanton (talk) 20:43, 21 January 2009 (UTC)
 * File:Eridanus constellation map.png doesn't have &epsilon; already labeled, but you could perhaps do something with that map. Photos can be a little more problematic because of licensing issues (per WP:Image policy).&mdash;RJH (talk) 22:38, 21 January 2009 (UTC)
 * Look at the File:Eridanus epsilon location.png. --Anton Gutsunaev (talk) 02:21, 24 January 2009 (UTC)
 * Yes, that should serve.&mdash;RJH (talk) 20:13, 24 January 2009 (UTC)

X-rays from Epsilon Eridani
If anyone is interested I have included some text in X-rays from Eridanus on X-ray emission from Epsilon Eridani. Please feel free to comment and include here. Marshallsumter (talk) 23:48, 29 December 2009 (UTC)

Planet b unconfirmed?
Seems to be rather a bit of controversy in the literature about whether this planet is confirmed. The discovery paper for the asteroid belts refers to it as "the long-suspected but still unconfirmed Jovian-mass planet with aorb = 3.4 AU that may be associated with the innermost warm debris belt detected by Spitzer" (emphasis mine). Certainly the astrometric orbit (given in the planet table here and on the Epsilon Eridani b article) is totally inconsistent with the debris disc structure... in fact a paper studying the dynamical stability of the ~3 AU asteroid belt suggests that the planet's orbit must be nearly circular. IMHO the best we can say while respecting the literature on this issue is that there is evidence that a giant planet exists with a period of approximately 2500 days, but its properties are highly uncertain and it is not universally regarded as a confirmed exoplanet detection. Icalanise (talk) 22:46, 13 January 2010 (UTC)
 * I've tried to modify the article to make it clear throughout that planet b is just a candidate.&mdash;RJH (talk) 22:33, 9 November 2010 (UTC)

Closest neighbor
I removed the following statement from the lead:
 * Its closest neighbor is the M dwarf binary system Luyten 726-8, at a distance of about 5 light years.

The only reference for this information is the SolStation web site, and it is unclear how reliable this information may be. I could not confirm it with a primary source.&mdash;RJH (talk) 22:33, 9 November 2010 (UTC)

Awkward usage or appropriate jargon?

 * Epsilon Eridani has a higher level of magnetically active than the Sun, so Epsilon Eridani demonstrates increased chromospheric activity and coronal activity.

"magnetic activity" or "is more magnetically active than" sounds better in English, but I'm not an astronomer. If this is a case of legitimate jargon, like obstetricians calling out measurements in "sontimeters", no need to fix.Timbabwe (talk) 13:06, 16 November 2010 (UTC)
 * Sorry, I mangled the edit. I'll take care of it. Thanks.&mdash;RJH (talk) 17:53, 16 November 2010 (UTC)

2023 - activity cycle update
A new paper dropped, and Ran is now found to have three overlapping activity cycles: 1060 ± 30 days / ∼2.9 years, 3970 ± 54 / 10.9 years, and 12,355 ± 230 days / ~33.8 years. AstroChara (talk) 13:46, 16 March 2023 (UTC)