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The following is an archived discussion of a featured article nomination. Please do not modify it. Subsequent comments should be made on the article's talk page or in Wikipedia talk:Featured article candidates. No further edits should be made to this page.

The article was promoted by User:SandyGeorgia 20:04, 12 August 2008 [1].

Proxima Centauri

[edit]
Nominator(s): RJH (talk)


This is a science article about the nearest star to the Sun. My hope is that it is reasonably accessible to a general audience, although some science background may help. It has undergone a PR; a check by BrighterOrange's script; reached GA status, and now I believe this page may satisfy the criteria for a Featured Article. Please take a look and let me know what you think. I'll try to address any specific concerns. Thank you.—RJH (talk) 17:50, 2 August 2008 (UTC)[reply]

  • Proxima Centauri was discovered to share the same proper motion as Alpha Centauri in 1915 by Robert Innes while he was Director of the Union Observatory in Johannesburg, South Africa. This is the sort of thing that gives the scientific passive a bad name. Please make it: Robert Innes, Director of the Union Observatory in Johannesburg, South Africa in 1915, discovered that Proxima Centauri had the same proper motion as Alpha Centauri. and so on in other cases. Septentrionalis PMAnderson 18:36, 2 August 2008 (UTC)[reply]
    • I updated the above text. Thanks.—RJH (talk)
  • 'a main-sequence star for another four trillion years' (from lead and repeated in text) Are you certain this is 4 trillion, not 4 billion? This seems an exceptionally long time. I don't have full access to the source so cannot check myself. GameKeeper (talk) 00:04, 3 August 2008 (UTC)[reply]
Checked a few more sources, very low mass stars do have such a potentially amazingly long life time. GameKeeper (talk) 00:11, 3 August 2008 (UTC)[reply]
There's a graph here: Red_dwarf#Description and characteristics.—RJH (talk) 16:57, 3 August 2008 (UTC)[reply]
  • Amongst the known stars, Proxima Centauri has been the closest star to the Sun for about 32,000 years and will be so for about another 9,000 years, after which the closest star to the Sun will be Barnard's Star. Surely Alpha Centauri.--Grahame (talk) 06:39, 3 August 2008 (UTC)[reply]
    • As the orbital period of Proxima (if any) is 500,000 years, I'd expect them to stay in roughly the same configuration during the above time frame. So that probably means Proxima will be closer than Alpha Centauri. But I changed the text. Thanks.—RJH (talk) 16:32, 3 August 2008 (UTC)[reply]
  • Support Comments - looked pretty good on first read-through - some copyedit issues will follow but first I have a couple of comprehensiveness questions. all potential deal-brekares dealt with, anything else is a bonus and we're over the line in my book. Cheers, Casliber (talk · contribs) 07:47, 3 August 2008 (UTC)[reply]
Casliber's issues and responses
Given we mention the Sun's appearance, but how bright would Toliman A & B be from Proxima? Casliber (talk · contribs) 07:47, 3 August 2008 (UTC)[reply]
Well, back-of-the-envelope-wise, I think the magnitude adjustment is about -10, so I think they'd be roughly -5/-4. Are you suggesting that this is needed for comprehensiveness? —RJH (talk) 16:54, 3 August 2008 (UTC)[reply]
If a reliable source could be found, I believe it should be in. If one can't, well then it can't. So, the answer would be if at all possible yes. Cheers, Casliber (talk · contribs) 20:27, 3 August 2008 (UTC)[reply]
This page lists the visual magnitudes as -6.6 and -5.2 respectively, so I was off a little on my guestimate. The question is, since the SolStation source might be considered suspect (per below), do we consider the Andrew James source sufficiently authoritative? It'd be nice to know his academic qualifications.—RJH (talk) 18:08, 4 August 2008 (UTC)[reply]
(sigh) agree. I find it hard to believe there are no RS's for this but had a look and can't find out who he is on the website. He is a member of the Astronomical Society of NEw South Wales and gets positive feedback from Douglas Snyder here...Cheers, Casliber (talk · contribs) 19:23, 4 August 2008 (UTC)[reply]
I'll include it as an external link.—RJH (talk) 14:18, 5 August 2008 (UTC)[reply]

Also, what would flares do to a hypothetical planet. Is there any info available? Casliber (talk · contribs) 07:47, 3 August 2008 (UTC)[reply]
This is discussed under "Possible companions", paragraph 4.—RJH (talk) 16:40, 3 August 2008 (UTC) [reply]
Hmmm..I guess for the reader, does it just mean the surface is bombarded by radiation? heat? Not hugely clear. Cheers, Casliber (talk · contribs) 19:23, 4 August 2008 (UTC)[reply]
As we're talking about a purely hypothetical planet here with unknown physical parameters, I think that would be excessive and bordering on OR. The effect upon the planet depends on whether it has a magnetic field, the strength thereof, and the existence of an atmosphere, including whether it is a gas gient. The topic really should be covered on the Flare star page. Sorry, I'm going to weasel out of this one.—RJH (talk) 19:30, 4 August 2008 (UTC)[reply]
No no, that's ok. I like reading alot about stars but am a real neophyte. Many of my questions here are not authoritative and i am feeling my way a bit. That expalins the situation well. Cheers, Casliber (talk · contribs) 19:34, 4 August 2008 (UTC)[reply]
The star's magnetic field is created by convection throughout the star,.. - 2 'star's flows funny. Just 'inner convection'? or is it self-exlanatory that convection is inside - would 'internal convection' suffice? Casliber (talk · contribs) 19:23, 4 August 2008 (UTC)[reply]
I'm attempting to say that 100% of the star is undergoing convection. Is that not the meaning of throughout?—RJH (talk) 19:31, 4 August 2008 (UTC)[reply]
OK, I get it now; still I was trying to figure out a way of not using the noun 'star' twice in the one sentence.Cheers, Casliber (talk · contribs) 19:47, 4 August 2008 (UTC)[reply]
I changed the second use of star to 'stellar body'.—RJH (talk)
Even during quiescent periods with few or no flares - why not just 'quiet'? Does the unusual 'quiescent' add anything that a plainer word doesn't?
Well, quiet is normally an acoustical term, whereas quiescent can apply to any activity. So I think it avoids a potential point of confusion.—RJH (talk)
Fair enough. Cheers, Casliber (talk · contribs) 14:24, 5 August 2008 (UTC)[reply]

::The activity level also appears to vary with a period of roughly 442 days, analogous to the Sun's solar cycle, which has a period of 11 years - 'The activity level also appears to vary with a period of roughly 442 days, shorter than the solar cycle of the Sun, which has a period of 11 years' --> too simple? Casliber (talk · contribs) 07:47, 3 August 2008 (UTC)[reply]

Modifed. Thanks.—RJH (talk)
Among the known stars, Proxima Centauri and Alpha Centauri have been the closest stars to the Sun for about 32,000 years .. - is there any likelihood there are unknown stars that are closer? If not I think we can remove the first 4 words. Casliber (talk · contribs) 07:47, 3 August 2008 (UTC)[reply]
Possibly; I can't say for sure. There are some red dwarfs that have high velocities, so perhaps one whipped by during that time period. Astronomers are still finding previously undiscovered red dwarfs. Just covering the bases.—RJH (talk) 14:18, 5 August 2008 (UTC)[reply]
OK, I am happy with that explanation. Cheers, Casliber (talk · contribs) 14:24, 5 August 2008 (UTC)[reply]
Is it worthwhile explaining any of its alternative names/designations in the body of the text?Cheers, Casliber (talk · contribs) 19:58, 4 August 2008 (UTC)[reply]
I wouldn't think so. The history of the catalogs is covered elsewhere and I haven't run into anything particularly interesting concerning Proxima Centauri.—RJH (talk)

More questions later. Cheers, Casliber (talk · contribs) 07:47, 3 August 2008 (UTC)[reply]

Thank you for the feedback.—RJH (talk) 14:35, 5 August 2008 (UTC)[reply]
  • A very fine article on an interesting subject. However, questions and comments on a few details. Kosebamse (talk) 12:42, 3 August 2008 (UTC)[reply]
      • Unfortunately I'll have to disagree with most of your conclusions. So, please pardon.—RJH (talk)
        • No prob, I see your points and don't oppose this nomination; nevertheless picking a few nits, see below. Kosebamse (talk) 17:31, 3 August 2008 (UTC)[reply]
          • Thanks for your comments and amendations. One problem is the excessive number of references and links which represent an amount of work that could have been invested far better into improving the article even further. Howeve, that seems to be counted as a bonus nowadays. Support FA. Ceterum censeo that this puerile referencing lunacy must be stopped. Kosebamse (talk) 20:56, 5 August 2008 (UTC)[reply]
            • Thanks for the support. As far as I know, articles are not written under a deadline. Hence your statement about the time allotment doesn't seem quite accurate. The article has as many references as it needs, and the addition of the citations did not detract from the time spent developing the article.—RJH (talk) 17:42, 6 August 2008 (UTC)[reply]
Kosebamse's issues and responses
    • "has been proposed as a destination for interstellar travel" While appealing to nerds and kids, the possibility of traveling there is currently so extremely remote that it should not be mentioned in the introduction.Kosebamse (talk)
      • The lead should be a summary of the article. This topic is discussed in the article. Whether it is a remote possibility or not is speculative; it's just an interesting fact, so I'd like to leave it in. Besides, just who is going to be reading this article?—RJH (talk)
        • Matter of taste. I think every article, and most of all every FA, should be as much as possible oriented towards a general readership.Kosebamse (talk)
          • True, but I'm inclined to keep it in the lead because it is discussed in an article section. Sorry, but I'm going to decline to agree with you on this one.—RJH (talk) 19:30, 4 August 2008 (UTC)[reply]
    • "Because of its proximity, the diameter of the star can be measured directly, and is one-seventh that of the Sun" in the intro should be at the beginning of the second paragraph. Important information first, please, readers want to form a mental image and the size is one of the most relevant pieces of information.Kosebamse (talk)
      • Well, personally, I find the fact that this is a flare star is quite important. It is a major distinguishing element of this star, and is a reason for a lot of astronomical investigation. Hence I think it is reasonable to put it first. Mass determines size, so that goes before dimension.—RJH (talk)
        • See my answer above re general readership. I'd guess a reader without much prior knowledge would have to look up what a flar star is, while size is readily understood.Kosebamse (talk)
    • "mass is about an eighth of the Sun's" and "the diameter of the star can be measured directly, and is one-seventh that of the Sun" deserves further explanation. Are those two pieces of information bullet-proof and iron-clad? As the volume changes with the cube of diameter, that implies an enormous difference in density between the Sun and Proxima centauri. I see it's explained further below, but a half-to-three-quarter-informed reader will stumble over that. Perhaps the actual density should be mentioned in this context.Kosebamse (talk)
      • The size is well determined and the mass comes from stellar models, so yes they are pretty solid. I think that the average density, while perhaps of interest to some, isn't important enough to include in the lead. It's a fairly useless parameter as most of the star will not be at that density. I just include it for completeness and to give some perspective. Is that reasonable?—RJH (talk)
        • The question of average or not average density is rather specialistic, but someone with a basic understanding of math or physics might stumble here and wonder whether such differences between densities of stars are real, even if they had read about white dwarfs, neutron stars and such.Kosebamse (talk)
          • Okay, I included a sentence, although I'll note this conflicts with your earlier statement about targeting a general audience. =) —RJH (talk)
    • Furthermore, in that same sentence, please use angular diameter which is the technically correct description (the actual diameter is not measured but calculated from distance and angular diameter)Kosebamse (talk)
      • Both the angular diameter and distance have relatively small margins of error. A reasonably accurate value can be derived thereof. I'm not sure I understand why a computed value is unsatisfactory here. A discussion of the derivation of the size would need to include information about limb darkening and fitting of computer models, which I'm not sure would be relevant.—RJH (talk)
        • Sorry to pick these nits, I don't object to the use of that value here, but it should not be described as "measured", because what's been measured are two other values from which the diameter can be derived.Kosebamse (talk)
          • I see your point. It has been corrected.—RJH (talk)
    • "Red dwarfs such as Proxima Centauri are, in general, far too faint to be observable with the naked eye" seems a little vague. Are there any at all that are observable? If so, which ones? If not, please strike "in general".Kosebamse (talk)
    • "If the Sun were to become as dim as Proxima, all of the planets except Venus" - the point becomes only clear to somebody who knows what makes planets shine. Given that most people believe that the moon's phases arise through an effect of Earth's shadow, or that the difference between stars and planets is generally not known etc. etc. (personal experience, I have asked many an otherwise well educated person), one should not assume that kind of knowledge of Wikipedia's readers. Please xplaijn some further, or perhaps leave it out.Kosebamse (talk)
    • "Because of Proxima Centauri's southern declination" - please link or explain "declination".Kosebamse (talk)
      • It is linked in the infobox.—RJH (talk)
    • "This illustration shows the relative sizes of (from left to right) the Sun, α Centauri A, α Centauri B and Proxima Centauri" is a little misleading. Relative to what? To each other, I presume? There are so many things in astronomy that are either named relative or absolute that this description might look slightly confusing to a reader with a degree of prior knowledge. Perhaps better "comparative sizes" or something along these lines?Kosebamse (talk)
      • Yes, their sizes relative to each other. Sorry, I thought it would be obvious. I used your suggested word instead.—RJH (talk)
    • "has been the closest star to the Sun for about 32,000 years and will be so for about another 9,000 years, after which the closest star to the Sun will be Barnard's Star." It's discussed some further below, but the question coming up at this point is whether this is due to the proper motion of Proxima centauri itself, its motion within the Alpha centauri system, the proper motion of the Alpha centauri system, or all or some of these. Perhaps that could be explained a little more clearly. Kosebamse (talk)
      • The statement has been modified, per the earlier issue.—RJH (talk)
    • Kosebamse (talk) 12:42, 3 August 2008 (UTC)[reply]

Comments

Otherwise sources look good, links checked out with the link checker tool. Ealdgyth - Talk 14:02, 3 August 2008 (UTC)[reply]
I have no idea; the page seems well researched and the information has proven mostly reliable. But it is the only source that lists the nearest stars. The alternative would be to compute it myself, but then we would have to do it for every star within a given distance to be certain. That would probably be too close to OR. Anyway, I relocated it to the talk page and asked for a better reference.—RJH (talk) 16:35, 3 August 2008 (UTC)[reply]
This is all they give us, nothing to meet WP:V: http://www.solstation.com/about.htm SandyGeorgia (Talk) 01:13, 10 August 2008 (UTC)[reply]

Comments on images

Comment Ref #25 is missing ISBN or some easy way to find the book. Also, you might want to consider splitting Notes and Refs parts. Nergaal (talk) 16:26, 12 August 2008 (UTC)[reply]

Thanks. You probably mean Campbell (1899), which was published before ISBN was established. (But I added in a link to the Google scan.) I considered a split along notes/references, but it is ugly trying to maintain a separate notes section because of the clumsy mechanism of the alternative citing system. I prefer to just let the back-end database take care of the tags. Sorry.—RJH (talk) 19:50, 12 August 2008 (UTC)[reply]
The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.
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