Talk:Epsilon Eridani/Archive 1

Archive 1

Archive 2

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.—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.—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.—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 ε 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).—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.—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 [1] refers to it as "the long-suspected but still unconfirmed Jovian-mass planet with a_orb = 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 [2] 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.—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.—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.—RJH (talk) 17:53, 16 November 2010 (UTC)

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

---

GA Review

This review is transcluded from Talk:Epsilon Eridani/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Modest Genius ^talk 01:28, 17 November 2010 (UTC)

GA review – see WP:WIAGA for criteria

1. Is it reasonably well written?

   A. Prose quality:

   The prose is mostly fine, with two caveats: 1) The early parts of the article have lots of short, sharp sentences saying 'the X is Y' and nothing more 2) Many of the sections are very long and should be split up into subsections

   I think I addressed most of these. The last two sections don't have good break points, so I left them be for now.—RJH (talk)

   I split up the planets section, feel free to revert if you don't think it works. Modest Genius ^talk 23:43, 23 November 2010 (UTC)

   I was a little reluctant to do that because of the resulting brevity of the sections, but I guess it's okay. Thanks.—RJH (talk)

   B. MoS compliance for lead, layout, words to watch, fiction, and lists:

   The external links section is formatted as list of references, despite the fact that these items are not actually used as such. If they support something in the article, they should be incorporated into the reference list; if not the papers don't add anything and should be removed.

   The two reference-style entries in the external links section were superseded by subsequent journal paper that are cited in the article, so I removed both.—RJH (talk)

2. Is it factually accurate and verifiable?

   A. References to sources:

   Gai et al appears twice in the reference list

   The Potemine reference gives the publisher as 'Cornell University Library'. This is incorrect. The link provided goes to Cornell's mirror of the arxiv; this reference should be cited properly.

   The Neugebauer reference is a general description of IRAS. Does it mention this star at all? If not, the reference has no place in this article, since anyone interested in IRAS can read our article on the subject (where this reference should appear).

   Still not sure about this one, but not a major point. Modest Genius ^talk 00:32, 24 November 2010 (UTC)

   The Greaves reference, which currently goes to an archived personal website, was apparently submitted to ApJ Letters. If it was published, the paper should be found and substituted for this reference.

   I found at least one reference whose title was given incorrectly (Whitehouse). You might like to check the others.

   I've addressed these and checked the bibcodes for the linked Journal articles to confirm they match the titles. Hopefully they are all correct now. Thanks.—RJH (talk)

   B. Citation of reliable sources where necessary:

   There are a few {{fact}} tags that need addressing.

   I'm not sure whether arxiv papers which have not been published in a peer-reviewed journal meet the requirements of WP:RS or not. The Chinese Journal of Astronomy & Astrophysics is probably OK, but only just (I've read an awful lot of crap in there).

   For the arXiv paper, I put in a brief qualification that this is the results of a simulation. There doesn't appear to be an alternative source for that information at present.—RJH (talk)

   I checked - unpublished arxiv is not generally an RS, unless the author is clearly a well-published researcher in the area. I'm not going to get paranoid about it though. Modest Genius ^talk 00:32, 24 November 2010 (UTC)

   Okay. As best I can tell, Dr. Potemine appears to be a mathematician at the Paul Sabatier University. I think he has published mathematical papers in peer-reviewed journals, so I'm not quite sure why his astronomy papers posted to the arXiv weren't also submitted. To me the paper seems on a par with a book reference.—RJH (talk)

   C. No original research:

   Seems fine. There was a section which was written to read like OR, but was supported in the source - I've rephrased it.

3. Is it broad in its coverage?

   A. Major aspects:

   Most things covered, see below for areas that need expanding

   B. Focused:

   See comment below on SETI

4. Is it neutral?

   Fair representation without bias:

   No problems I can see, seems to do a good job handling the reality or otherwise of the planets.

5. Is it stable?

   No edit wars, etc:

   Seems fine

6. Does it contain images to illustrate the topic?

   A. Images are copyright tagged, and non-free images have fair use rationales:

   Look good to me. I tweaked author info for one image, everything else checks out.

   B. Images are provided where possible and appropriate, with suitable captions:

   Images seem fine, but some captions need improving. Each image should specify what is being shown, and artists impressions should be captioned as such. Nice work on the images you made yourself!

   I've attempted to enhance and clarify the image captions. Thank you.—RJH (talk) 20:17, 21 November 2010 (UTC)

   I did some further tweaking of my own, they look good now. Modest Genius ^talk 00:32, 24 November 2010 (UTC)

7. Overall:

   Pass or Fail:

   Nothing too major to fix, on hold.

Specific comments

• I've added a few {{clarify}} {{specify}} etc. tags at various junctures. The exact queries are in comments in the article code.
  • These were addressed.—RJH (talk)
    • I've struck this, but will need to have another detailed read to check. Modest Genius ^talk 00:32, 24 November 2010 (UTC)
• 'Epsilon is the fifth letter in the Greek alphabet, and it was normally assigned to the fifth brightest star in the constellation' This is not true. Bayer (mostly) assigned letters to each (naked eye) magnitude in turn, but within each magnitude class the order was from the 'head' to the 'tail' of each constellation. See Bayer designation, this is also the explanation for the 'reversed' names of alpha Ori and beta Ori.
  • Fixed. Thanks for the clarification.—RJH (talk)
• The revised Hipparcos parallax is 310.94±0.16 mas ([3], 2007A&A...474..653V) which should be used instead of the original 1997 value. The proper motions should also be taken from the revised catalogue.
  • Done. —RJH (talk)
• The observation history section gives an awful lot of weight to SETI observations. If the reader didn't know better, they would think this was the main source of interest in the star. I suggest splitting the SETI information into a subsection, separate from the conventional observational history (which would be nice to expand, but not necessary for GA).
  • Done. I think I've pretty much covered the observation history prior to the modern period. It just wasn't considered a very interesting star until recently. But I'll look some more.—RJH (talk)
    • Thanks. Nearby K stars were indeed considered somewhat boring until exoplanets came along. Just a random thought - is e Eri included in any of the transit surveys? Might be in SuperWASP's programme. Modest Genius ^talk 00:32, 24 November 2010 (UTC)
      • I checked the SuperWASP public archive, but there were no results for Epsilon Eridani.[4]—RJH (talk) 20:49, 29 November 2010 (UTC)
• If the star is indeed part of the UMa moving group, that implies an age of 500 Myr, which should be mentioned in the discussion of the age.
  • Done.—RJH (talk)
• Given that an entire article exists on Epsilon Eridani in fiction, a paragraph or two should be added on this and {{main}} used to link to that article. The same use of {{main}} should be incorporated for the b and c planets.
  • That article is completely unsourced and mostly consists of trivial drek. It just didn't seem worth adding.—RJH (talk)
    • Fair point. Same with the rather bizarre X-rays from Eridanus. I've added links to the two planet articles using {{see}}, since they have less prose but more data than this one. Modest Genius ^talk 00:32, 24 November 2010 (UTC)
• Because of its proximity and probable planet(s), this star has been discussed as a plausible target for an interstellar probe, which should be mentioned. See eg. [5] [6]
  • Yes I was a little borderline on adding that one, since any information I added would be more or less true for multiple nearby stars. But I added a sentence with sources for the interested reader.—RJH (talk)
• 'where an astronomical unit is equal to the average distance between Earth and the Sun' I have two problems with this statement: 1) It's towards the end of the article, after AU has been used many times already; 2) It's not quite true, see astronomical unit#Definition. Either correct it and move it to the first usage of AU, or remove it.
  • Okay, I just removed it since there is a unit conversion in the lead.—RJH (talk)

Not required for GA

These are some comments of problems/things that could be improved which are not necessary to pass the GA criteria, but I thought would be useful to note down anyway.

• There are several date formats in use in the reference list, and multiple forms of journal titles (eg. both 'Astronomy and Astrophysics' and 'Astronomy & Astrophysics' appear, with inconsistent linking)
  • These should be fixed up now.—RJH (talk)
• Whilst there are excellent images for the planetary system, the rest of the article is a bit bare. Since this is such a bright star, there should be suitable some freely-available images somewhere eg. from amateur astronomers, perhaps of the constellation or the Ori-Eri shell.
• Running through the checklinks tool (see top right of this page) shows a mix of linking for references - some go to arxiv, others to ADS, and a minority to the journal web pages. This should be consistent - I think the guidelines are to link the title to the journal website and additionally include arxiv, ADS and doi links in the relevant template parameters.
  • I believe I have them all set okay now.—RJH (talk)

Review placed on hold for one week

Modest Genius ^talk 05:24, 19 November 2010 (UTC)

Thank you for the detailed review. I think I've addressed the fact tags; the remainder will take longer.—RJH (talk) 18:09, 19 November 2010 (UTC)

OK, it's almost there, just a handful of items left to fix. Modest Genius ^talk 00:32, 24 November 2010 (UTC)

Thanks. I'm on vacation this week so I haven't had a lot of time to work on the remainder. I'll try to address them when I have more time, but feel free to fail the GAC if you feel the need. I can take it through again when it's fixed up.—RJH (talk) 20:52, 24 November 2010 (UTC)

Nah, no problem, I'm happy to extend the time period. Modest Genius ^talk 03:10, 25 November 2010 (UTC)

GA nomination passed

Righto, all my concerns have been addressed, so I'm passing the GA nomination. I'm supposed to encourage you to review one of the articles on WP:GAN to help reduce the backlog. Congratulations! Modest Genius ^talk 01:59, 29 November 2010 (UTC)

Great! Thanks again for taking the time to review the article. You've been very helpful.—RJH (talk) 19:49, 29 November 2010 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.