Talk:Alpha Centauri

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Astronomy / Astronomical objects  (Rated B-class, Top-importance)
WikiProject icon Alpha Centauri is within the scope of WikiProject Astronomy, which collaborates on articles related to Astronomy on Wikipedia.
B-Class article B  This article has been rated as B-Class on the project's quality scale.
 Top  This article has been rated as Top-importance on the project's importance scale.
Taskforce icon
This article is supported by WikiProject Astronomical objects, which collaborates on articles related to astronomical objects.
 

Article Main Image[edit]

The current caption for this image is "α Centauri and β Centauri, with Proxima circled". Should it actually be "α Centauri-A and α Centauri-B, with Proxima circled" ? KevinTernes (talk) 21:03, 11 December 2015 (UTC)

No, that is actually the two separate stars, α Centauri and β Centauri. Where α Centauri is marked, it's both A & B. Tarl.Neustaedter (talk) 22:26, 11 December 2015 (UTC)

Repetitiveness[edit]

Having both a Component designations and Nature of the system seems repetitive. I suggest we fold them in together to describe the system more succinctly. Any objections? NB: discussion in the first paragraph about brightness better suited to Observation section really. Cas Liber (talk · contribs) 05:05, 21 January 2014 (UTC)

Confusing Paragraph: View from a Hypothetical Planet[edit]

I believe the paragraph is not serving purpose of a clear/proper explanation of what is happening there:

  • Assuming this hypothetical planet had a low orbital inclination with respect to the mutual orbit of Alpha Centauri A and B, then the secondary star would start beside the primary at 'stellar' conjunction.

I think this first sentence wants to say that at a moment of the planet orbit we have the 'stellar conjunction' and we consider it start (if there were humans they would most probably have a big celebration related to this, however it does not necessarily mean it would start their 'year', because the possible '4 seasons cycle' could have been totally independent from the 'stellar' conjunction and that conjunction would be every 'year' in another 'day' relative to solstices (or better said AlphaCen-AorB-stices ;)

  • Half the period later, at 'stellar' opposition, both stars would be opposite each other in the sky.

The position of the stars relative to the position of the planet depends primarily on the position of the planet orbiting around a star, so the period we are talking about is the planet's 'year'. Still we need to take into account that B has its own orbit around A and it adjusts the period between the two subsequent 'stellar conjunctions' by about Y/80 of our year, where Y is the planet's 'year' in our years (though even this is far from exact, because the stellar orbit is quite eccentric and so the apparent move of the other star on stellar sky varies from Y/40 to Y/160 in the 80 years period). Moreover, the more eccentric is the planet's elliptical orbit the less regular are the moment's of conjunctions. In the planet's year when the main axis is more-less perpendicular to line A-B connecting the star's, the period between 'stellar conjunction and opposition' could be much shorter than the second "half" (or vice versa)...

Then, for about half the planetary year the appearance of the night sky would be a darker blue – similar to the sky during totality at any total solar eclipse.

This is quite misleading, because the opposition does not last half the planetary year - it is only one extreme moment. Even if the orbit was circular, after quarter the year we would have (in ideal case of zero planet axis inclination) quarter of the day (= half of the night) dark. So the effect of B "shining" in the early morning (or late evening) would be not more impressive than our longer days during summers let's say in Germany or even better in Sweden.

  • Humans could easily walk around and clearly see the surrounding terrain, and reading a book would be quite possible without any artificial light.[105]

Yes, at the time when at least one of the stars (the planet's "sun" or the other star the planet is not orbiting around) is actually on the sky (ideally not near to horizon).

  • After another half period in the stellar orbit, the stars would complete their orbital cycle and return to the next stellar conjunction, and the familiar Earth-like day and night cycle would return.

Why stellar orbit? We are talking about the planetary orbit and its year cycle adjusted by only about Y/40-Y/160 with the stellar cycle all the time. Stars complete their cycle in about 80 years and the cycle we are talking about takes a bit more than the planet's year (about Y*(1 + Y/80) in our years).

Overall I suggest to rewrite the paragraph from scratch. Either it should just explain that sometimes B could shine at 'midnight', so that "Humans could easily walk..." and do not provide any misleading 'timing' information or it should provide correct information. I would like to hear from anybody what he would prefer. Thanks.

Eltwarg (talk) 23:06, 27 April 2014 (UTC)

Again. As the author who introduced this section, the information given explains the nature of the two stars in this binary system. Whilst such planets are indeed theoretical, we have to select at least a starting point. I.e. A planet similar to Earth at similar distance from the Sun. From the many frequent questions from students to amateur astronomers that are curious about the orbit and nature of the stars — especially, when compared to the sun, IMO this text is worthwhile for the sake of clarity and unnecessary debate.
If you think this is unnecessary, please state why. Also a star at −18.2 magnitude is 180 times brighter than the moon. so a "theoretical Earth-like planet" would be bright enough to read a book. (You can read a book via moonlight.) Frankly, the points here are trivial. Again. it is meant to present a perspective on a planet within the Alpha Centauri system. Worst, there is no descriptors of planets within double star systems. Elwarg has failed in seeing this perspective. Arianewiki1 (talk) 13:03, 31 May 2014 (UTC)

Large negative stellar magnitudes are not in common use, because such heavenly bodies are rare on Earth, so it would be difficult for a reader to find a familiar reference. Illumination in lux is commonly used and encountered for the ranges in question. — Preceding unsigned comment added by 213.35.248.23 (talk) 07:46, 20 February 2016 (UTC)

The picture[edit]

On the article's main illustration named Alpha "Centauri A/B" it is unclear if the two circles mark the actual angular diameters or not. I guess they do not, as it would require the photo to be made almost during an eclipse + the earth must lie close to the system's orbital plane. — Preceding unsigned comment added by 95.174.213.117 (talk) 18:07, 28 May 2014 (UTC)

Many of the pictures in this article are particularly unhelpful. It needs a good purge, keeping only the most useful of the lot or finding clearer replacements. Praemonitus (talk) 21:15, 16 March 2015 (UTC)
Indeed. I have gone ahead and removed a few. However, it could probably use more cleanup. --JorisvS (talk) 22:53, 16 March 2015 (UTC)

Contradictory Facts In Article[edit]

The introduction to this article states: "The separation of Proxima from Alpha Centauri AB is about 0.06 parsecs, 0.2 light years or 13,000 astronomical units (AU); equivalent to 400 times the size of Neptune's orbit."

Section 6 of the article states: "Companion: Proxima Centauri", states: " . . . Proxima, is about 15,000 AU away from Alpha Centauri AB."

Thus, the article's Introduction and Section 6 contain contradictory information regarding the distance of Proxima Centauri from Alpha Centauri AB. Please fix.— Preceding unsigned comment added by 2602:30a:2c98:cdc0:9879:f210:412a:ad1d (talkcontribs) 06:30, 13 March 2015‎

Good point. Referenced text is preferred to general text in introduction, so changed to 15,000. Thanks, good pick-up!! Arianewiki1 (talk) 14:02, 13 March 2015 (UTC)

Planet v. Exoplanet[edit]

@JorisvS: JorisvS Definition, as stated in Wikipedia itself.

"An exoplanet or extrasolar planet is a planet that does not orbit the Sun and instead orbits a different star, stellar remnant, or brown dwarf."[1]

Also it the same page says; "The nearest known exoplanet, if confirmed, would be Alpha Centauri Bb, but there is some doubt about its existence. "

Oxford dictionary on-line defines: "A planet which orbits a star outside the solar system." [2]

For example, the IAU states; "The first exoplanet tentatively identified around the second brightest star in the triple star system, Alpha Centauri, is accordingly called Alpha Centauri Bb. If an exoplanet orbits both of the stars in a binary system, its name can be, for example, Kepler-34(AB) b." [3]

I can access more than another dozen references to support this.

Planets around other stars are exoplanets and not planets. Hence, definition of planets within the Solar System, as edited.

Please get your facts right before editing, and revert my edit please.

(Note; The alternative form are 'solar planets' and 'extra-solar planets', actually. If you were to discuss this with the IAU, you will find control is with WGEP (Working Group on Extrasolar Planets) in Commission 53 'Extrasolar Planets', which has existed since August 2006.

Please show evidence of the contrary statement. Thankx. Arianewiki1 (talk) 17:55, 17 March 2015 (UTC)

"An exoplanet or extrasolar planet is a planet that ...". Exactly what I said! All exoplanets are planets, but not all planets are exoplanets. "Planet" does not mean specifically those eight in the Solar System. Wherever "planet" is correct and clear, there is no need to use "exoplanet". In "The nearest known exoplanet, if confirmed, would be Alpha Centauri Bb ...", saying "exoplanet" is necessary because "the nearest known planet" means something distinctly different. As for the IAU definition, they just didn't want to deal with exoplanets, where our knowledge is far less. --JorisvS (talk) 18:20, 17 March 2015 (UTC)
What? Can't you read the above text?
Another Definition: "The definition of planet, since the word was coined by the ancient Greeks, has included within its scope a wide range of celestial bodies. Greek astronomers employed the term asteres planetai (ἀστέρες πλανῆται), "wandering stars", for star-like objects which apparently moved over the sky." [4]
Exoplanets don't wander across the night sky, but the planets of the Solar System do, so the term 'exoplanet' has been used.
IAU says;
"A planet is any object in orbit around the Sun with a diameter greater than 2000 km.
A planet is any object in orbit around the Sun whose shape is stable due to its own gravity.
A planet is any object in orbit around the Sun that is dominant in its immediate neighbourhood." [5]
Also. Exoplanets don't orbit the sun, now do they?
As for " As for the IAU definition, they just didn't want to deal with exoplanets, where our knowledge is far less." So what. This statement is irrelevant. This is not reference that supports the use of 'exoplanet' not 'planet'. I.e. YOUR opinion. Please give evidence for this statement.
Either come up with actual evidence of the contrary statement, which counteracts this statement (and is not based on your own opinion), or revert. Thanx.. Arianewiki1 (talk) 18:46, 17 March 2015 (UTC)
Seriously, you're going to include the Ancient Greek definition to argue for your position?? What is seriously so hard about simply reading both the definition you've given above or the one at exoplanet, "An exoplanet or extrasolar planet is a planet that does not orbit the Sun and instead orbits a different star, stellar remnant, or brown dwarf.". These state crystal-clearly that an exoplanet is a planet! Moreover, Planet says "More than a thousand planets around other stars ("extrasolar planets" or "exoplanets") have been discovered in the Milky Way". And as for your naive legalistic reading of the phrasing of the IAU definitions: read Exoplanet#Definition. That exoplanets are also planets is emphatically not my opinion. And if you don't want to believe me and the articles to which I refer, why don't you take it to WP:Astronomy and see the reactions from other editor. --JorisvS (talk) 21:00, 17 March 2015 (UTC)
@JorisvS: Again, you are interpreting this incorrectly, and is it is clear you have need to provide a reference that supports your claim. The IAU definitions are absolute, agreed by international agreement. I.e. You earlier stating "As for the IAU definition, they just didn't want to deal with exoplanets, where our knowledge is far less.", is proof your arguments are plainly flawed. By your logical, dwarf planets are planets too, which is clearly wrong.
Whether exoplanets are planets or not relevant actually, because the adopted definition exists to distinguish between them. I.e. planets orbit the sun, while exoplanets orbits other stars. Why ignore it? They are planetary bodies, but strictly, they are not defined as planets. Again, you still have not provided ANY independent source that contradicts this. I.e. The IAU definitions are verifiable and cited sources. Unless you can really provide some relevant verifiable source, WP:Astronomy is irrelevant, UNLESS you can provide verifiable sources as citations to contradict this. So far you have provide none. Arianewiki1 (talk) 22:05, 17 March 2015 (UTC)
You're basically claiming all our articles on this topic are completely wrong in this respect (even though they're sourced and stable). The definitions (including the one you came with above!) say what I've been telling you the whole time. All the necessary references are in the articles, but you haven't actually come with one that supports your position. Yet somehow you want me to find (other?; there are already in the articles) references to support my position. It is you who should find references that actually support your position. And try to get your logic straight, nowhere did I claim that dwarf planets are also planets. You wouldn't be downplaying WP:Astronomy if you didn't know you'd find yourself arguing against lots of people, not just me. --JorisvS (talk) 22:39, 17 March 2015 (UTC)
All references are these…
1) Definition, as stated in Wikipedia itself.
"An exoplanet or extrasolar planet is a planet that does not orbit the Sun and instead orbits a different star, stellar remnant, or brown dwarf."[6]
2) Also it the same page says; "The nearest known exoplanet, if confirmed, would be Alpha Centauri Bb, but there is some doubt about its existence. "
3) Oxford dictionary on-line defines an exoplanet as: "A planet which orbits a star outside the solar system." [7]
4) For example, the IAU states; "The first exoplanet tentatively identified around the second brightest star in the triple star system, Alpha Centauri, is accordingly called Alpha Centauri Bb. If an exoplanet orbits both of the stars in a binary system, its name can be, for example, Kepler-34(AB) b." [8]
All these are obvious cited references. Yet you have yet to provide a single cited reference!!!
Plainly if "An exoplanet or extrasolar planet is a planet that does not orbit the Sun and instead orbits a different star,…" Then a planet orbits the Sun, and an exoplanet does not orbit the Sun. They may be planetary bodies, but they differ in definition because they orbit either the sun or other stars. Arianewiki1 (talk) 23:07, 17 March 2015 (UTC)
Your statement: "You wouldn't be downplaying WP:Astronomy if you didn't know you'd find yourself arguing against lots of people, not just me. -" Please find actual evidence to support this statement please. I.e. You are an individual, and cannot argue for other peoples point of view nor make statements of 'fact' based on assumptions. This is plainly falsifying consensus. Also WP:Astronomy is quite irrelevant, as fact here is based on cited or valid references. I.e. Logically, if Alpha Centauri has a planet orbiting this star, then the term exoplanet applies NOT planet. You need to provide a specific reference that says otherwise. (not what you just think is true.) Arianewiki1 (talk) 23:24, 17 March 2015 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── Ariane, your last quote clearly states that exoplanets are planets. I'm sorry you're having difficulty understanding your sources, but they're quite clear.

As for when to use which term, "exoplanet" is usually used when plain "planet" would be ambiguous. Once in the context of a particular planetary system, as in this article, "planet" is all that is needed. — kwami (talk) 23:13, 17 March 2015 (UTC)

No. Not according to the IAU. Please state a cited reference(s) that your statement is true. Arianewiki1 (talk) 23:27, 17 March 2015 (UTC)
You keep demanding sources, so provide your source. We are not contradicting the 2006 IAU definition of "planet"; if you have some other IAU source, please share. — kwami (talk) 23:51, 17 March 2015 (UTC)
To revert an Article edit, you should cite reference(s) that validate the errors, especially when seeking consensus. I have already provided the citation that support this, but you have reverted without proper discussion on this talk page. Please state a cited reference(s) that your statements are true. Arianewiki1 (talk) 23:35, 17 March 2015 (UTC)
You don't seem to understand how things work around here. Please read WP:BOLD. Since they're your edits, it's up to you to justify them, and to convince the rest of us. As it is, you've provided refs that disprove your claims. (That is, all we need to do to provide refs is to repeat the refs that you gave!) If you continue to WP:edit war, I will ask to have you blocked for disrupting the encyclopedia. — kwami (talk) 23:44, 17 March 2015 (UTC)
The page has now been protected, which has probably saved you from being blocked. Please consider your logic: You're arguing that exoplanets are not planets because exoplanets are planets! — kwami (talk) 23:47, 17 March 2015 (UTC)
Please stop making false statements. I.e. "You're arguing that exoplanets are not planets because exoplanets are planets!" That is not true. I am arguing the definition of exoplanets and planets, which are not the same definition. A planet that orbits another star is called an exoplanet. Please give citations to the contrary. (You haven't even done that.) Also my last edit followed the usage adopted in the cited references, not my own. If it is in the article title, is should follow that usage. Also note the IAU has defined the use of exoplanet, and is currently involved in their naming. [[9]] Note: WP:edit war here also applies to you too. Arianewiki1 (talk) 00:03, 18 March 2015 (UTC)
Do you even understand what you're saying?? "A planet that orbits another star is called an exoplanet.": Here you're, again, saying that exoplanets are planets. That sentence would be self-contradictory if exoplanets were not planets! --JorisvS (talk) 01:35, 18 March 2015 (UTC)
Actually, I'm saying "An exoplanet is a planet that orbits another star (i.e., not the Sun)." (See below.)
It is the definition that is important here. Exoplanets orbit other stars, not the sun!!!
Yet you unbelievably change under the title "Designations for exoplanets", that "Currently, according to the IAU, there is no agreed system for designating planets orbiting around other stars.". This statement is obviously false. Arianewiki1 (talk) 01:57, 18 March 2015 (UTC)
Exoplanets do orbit other stars, not the Sun. All exoplanets are planets, but not vice-versa, just like all apples are fruits, but not all fruits are apples. Why do I remove exo from ""Currently, according to the IAU, there is no agreed system for designating planets orbiting other stars."? Because "exoplanet"="planet orbiting another star", which means that "exoplanets orbiting other stars" is a tautology. It is sufficient to say "Currently, according to the IAU, there is no agreed system for designating planets orbiting other stars." OR "Currently, according to the IAU, there is no agreed system for designating exoplanets.". --JorisvS (talk) 02:06, 18 March 2015 (UTC)
Here "designating planets" does not equal "definition" of planets or exoplanets. Here "designating planets" is actually the current programme to name or class these exoplanets!! We are talking about "astronomical / scientific definitions", and how they are specifically defined. Planets from the perspective of sun or the stars behave differently and are discovered differently by differing methods. There are many good reasons to do this, and not just because they sizeable planetary bodies are made of rock, ices or gas. Arianewiki1 (talk) 03:00, 18 March 2015 (UTC)
Never did I say that "designating planets"="definition". Just because we need distinct methods to discover exoplanets (which is simply due to their distant location) does not mean that there is any meaningful physical difference that would warrant "exoplanet"≠"planet". Time and again here you've said that exoplanets are planets (e.g. "An exoplanet is a planet that orbits another star" literally says that exoplanets are planets), only to then try to use that to deny the very thing you've said. Your argument is logically incoherent and wrong. --JorisvS (talk) 03:10, 18 March 2015 (UTC)
The desperation here beggars belief. 'exo-' prefix means outside, and the term literally means a planet outside the solar system. Again. the scientific definition is more important, else why bother making a difference between planetary types. I.e. Let's call them all planets, and be done with it. Let's be foolish and just totally ignore the IAU and all the associated institutions, and pretend JorisvS is the guru of astronomical on all this. So when +5000 of them are named by the IAU, general confusion will ensue, as we will not know where or why they are placed. Who cares if we cannot differentiate between the brown dwarfs, or the hot Jupiters, massive Neptunes, gas dwarfs or super-earths. Yet there are big difference between the two designations are much uncertainty, and if you read the exoplanet page, the reasons are plainly stated.
Yes, the exo- designation hasn't been added there for fun, and when the IAU decides of a scientific definition, aligned on expertise and knowledge, we get this madcap libertines (like those who want to resurrect Pluto) who feel these things should be made on some weird democratic principle - made worse by openly sledging the IAU without wisdom to understand why. (Didn't you think someone notices continuous edits of Pluto page?]
Again. Show references that refute the difference between planet and exoplanet, or even why it is necessary to have a term "exoplanet." According to your own twisted logic, it is just unnecessary. Yet you still haven't show even one single example!! Arianewiki1 (talk) 05:39, 18 March 2015 (UTC)
Again you're interpreting me way off. Of course, "exoplanet" is a useful term, I have never claimed it isn't. You've provided a number of quotes that say exoplanets are planets, yet you're trying to use them for the exact opposite of what they're saying (makes perfect sense...not). And if your claim, for you have given no actual sources and actually opposite quotes, is right, our Exoplanet and Planet articles, and the sources they are based on, are dead wrong (and no, I didn't write them). --JorisvS (talk) 09:30, 18 March 2015 (UTC)

——

@StringTheory11: @Kwamikagami: @JorisvS: Well under the Exoplanets Data Explorer [10], which collects all the data on exoplanets, it plainly says straight out in FAQ.

"An exoplanet is a planet that orbits another star (i.e., not the Sun)."

Under Wikipedia's own IAU "The official definition of "planet" used by the International Astronomical Union (IAU) only covers the Solar System and thus does not apply to exoplanets." See also Astronomical naming conventions

The iAU formally says [11];

"A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit."

They further say "Contemporary observations are changing our understanding of planetary systems, and it is important that our nomenclature for objects reflect our current understanding. This applies, in particular, to the designation "planets". The word "planet" originally described "wanderers" that were known only as moving lights in the sky. Recent discoveries lead us to create a new definition, which we can make using currently available scientific information."

That new definition defines exoplanets.

This evidence cannot be more obvious. Unless you have a different written contrary definition from another source, and can also cite it, then this should be then used as it applies to both WP:MOS and WP:NASTRO. All the IAU definitions are the primary absolute source here, and are recommended in syntax and definition of astronomical bodies.

In the end, this follows the conventions here, and should be adopted as per my given WP:GF edits.

If existing definition of Wikipedia (and the IAU) are not adequate, especially for users who properly apply it, consensus is not required. (Else change the definitions.)

Furthermore, these statements by others above;

""Planet" does not mean specifically those eight in the Solar System."
"As for the IAU definition, they just didn't want to deal with exoplanets, where our knowledge is far less. "
"These state crystal-clearly that an exoplanet is a planet!"
"You're basically claiming all our articles on this topic are completely wrong in this respect (even though they're sourced and stable)."
""You wouldn't be downplaying WP:Astronomy if you didn't know you'd find yourself arguing against lots of people, not just me.""
"As for when to use which term, "exoplanet" is usually used when plain "planet" would be ambiguous."
"Once in the context of a particular planetary system, as in this article, "planet" is all that is needed."
"You're arguing that exoplanets are not planets because exoplanets are planets!"
"As it is, you've provided refs that disprove your claims."

These statement are all false. I would possibly suggest you should strike them out.

Note: As for "If you continue to WP:edit war, I will ask to have you blocked for disrupting the encyclopedia." stated by kwami. I perceive this as a direct threat against WP:GF and WP:CIV. Your own two reverts of the text and actually avoided to gain consensus by disregarding this discussion, which I had instigated on JorisvS revert. So far not one cited reference has been given here by JorisvS nor kwami to support the case. I request you kindly strike this offending remark immediately. Thankx. Arianewiki1 (talk) 01:50, 18 March 2015 (UTC)

Again, you're providing our sources for us, as all of your sources contradict you. I don't know how to address what appears to be functional illiteracy. (That's not an attack. When you present a source that defines 'planet' as we do, and then claim it says the opposite, I can only conclude that you are not able to parse academic written English. Or even Wikipedia articles, for that matter.) As for the IAU, they specifically say that they only address the Sol system. — kwami (talk) 01:57, 18 March 2015 (UTC)
Plainly you just don't get it. "An exoplanet is a planet that orbits another star (i.e., not the Sun)."
So quite logically. Definition of Alpha Centauri is called a exoplanet. The term is used not to confuse a planetary body orbiting the sun.
If a planet orbits another star, it is defined as an exoplanet.
If a planet orbits around the sun, it is defined as a planet.
How can a planet orbit around a distant star then be a planet?
It ain't illiteracy, is plainly logical…
So which statement above is therefore false, then? 02:10, 18 March 2015 (UTC)
The false statement is "if a planet orbits around the sun, it is defined as a planet". As for your question, "how can a planet orbit around a distant star then be a planet?", simple: because, as you just said, it's a planet.
I'll give an analogy to your argument: A rocky planet (formed inside the frost line) is a terrestrial planet. Earth is a terrestrial planet. Therefore, Earth is not a planet. That is spurious logic.
Or, to paraphrase you above, An exoplanet is a planet that orbits another star. So, quite logically, an exoplanet is a planet because your definition assumes it as a planet! — kwami (talk) 02:34, 18 March 2015 (UTC)
Again, plainly wrong. As I said above;"We are talking about "astronomical / scientific definitions", and how they are specifically defined. Planets from the perspective of sun or the stars behave differently and are discovered differently by differing methods. There are many good reasons to do this, and not just because they sizeable planetary bodies are made of rock, ices or gas." Where they reside is what's important here. Arianewiki1 (talk) 03:04, 18 March 2015 (UTC)
I have no opinion on this issue, and my only involvement is protecting the page to stop the edit-warring, which is not an endorsement of the current version. StringTheory11 (t • c) 02:06, 18 March 2015 (UTC)
@StringTheory11: I didn't expect otherwise. Just wanted to show this is being properly discussed on the talk page here, and not expecting endorsement nor condemnation. Arianewiki1 (talk) 02:14, 18 March 2015 (UTC)

(Exo)planet in the intro[edit]

The intro contains a whole paragraph about the confusion over whether a planet exists or has been detected in the system. Since this is so spurious at the moment, I think the whole para should be removed from the intro. The intro should summarise the established facts of the article. Ashmoo (talk) 12:57, 24 March 2015 (UTC)

It was way too detailed for the lead, even if no one would doubt its existence. However, regardless of whether doubt exists over its existence, it has been notable enough to merit a short mention in the lead, at least at present. I have pruned it. --JorisvS (talk) 14:18, 24 March 2015 (UTC)
Great, your version looks perfect to me. Ashmoo (talk) 15:07, 24 March 2015 (UTC)
I have no disagreement with this edit. Arianewiki1 (talk) 16:16, 24 March 2015 (UTC)

Alpha Centauri ABb and the hypothesised orbital period[edit]

It says in the, "Other possibly detected planets", section of this Wikipedia article, that Russian scientists have discovered a planet that would, "...be located at a distance of 80 AU and would orbit both stars with an orbital period of about 100 years." But, if a planet was orbiting Alpha Centauri AB at 80 AU, in a reasonably circular orbit, it would take at least 500 years to complete. Even a highly eccentric orbit would take about 200 years, 180 years at minimum if the semi-major axis was 40 AU and then the planet would either be grazing the stars or going between them. So, it is hard to take seriously the 100 year figure quoted, unless it's a rogue planet travelling at a faster velocity and then it's not actually in orbit around the stars.

Also neither does this Wikipedia article, or the reference source given by it, say where the source of the data, the Russian scientist used to discover the planet, came from. You obviously can't see Alpha Centauri from the Pulkovo Observatory in St. Petersburg. So, the Russian scientists must've analysed data obtained from some other observatory, but from where?

I quickly glanced at all the presentations made at the "Journees 2014", held by Central Astronomical Observatory of the Russian Academy of Sciences in St Petersburg, Russia. The conference presentations can be viewed at http://www.gao.spb.ru/english/as/j2014/programme.htm. But, only one presentation made there, "Shevchenko I. (invited) Resonances in the Solar and exoplanetary systems. - Presentation", seems to refer to Alpha Centauri at all and it's not, as far as I can tell, even talking about a planetary discovery there.

The only evidence given in this Wikipedia article, for the circumbinary planet discovery, is a reference to a "TASS Russia News Agency" report and not a scientific paper. Is that really a reliable enough source to trust here? — Preceding unsigned comment added by 86.176.162.206 (talk) 02:30, 1 April 2015 (UTC)

It is supposed to have been calculated that should be there, without much detail about why it should be there. And then the second source talks about the possibility of liquid water without going into the necessary detail to understand what is going on. On the one hand is it impossible to see, yet somehow there has been a spectral analysis. I, too, calculate that at a semi-major axis of 80 AU it should have an orbital period of ~500 years. Orbital period does not change with orbital eccentricity, only semi-major axis. I cannot locate any scientific article about this. It smells like a hoax. --JorisvS (talk) 09:33, 1 April 2015 (UTC)

Alpha Centauri B's rotational period[edit]

From the main text:

"The projected rotational velocity ( v·sin i ) is 1.1 ± 0.8 km·s−1, resulting in an estimated rotational period of 41 days. (An earlier, 1995 estimate gave a similar rotation period of 36.8 days.)"

Yet the infobox says that the rotational period for B is 47 days.

Both the text and the box agree that the rotational period for A is about 22 days (although the infobox allows some variability: "~22.5 ± 5.9 days"

Is more consistency possible here? 108.246.206.139 (talk) 05:27, 24 June 2015 (UTC)

Redundant Sentence?[edit]

In the section, Companion: Proxima Centauri, the last sentence in the first paragraph is, "It is not yet certain whether Proxima and Alpha Centauri are truly gravitationally bound."

Isn't this sort of redundant? I'm pretty sure people could get that by the time they even reach that sentence. I mean, it does say, "However, it is also possible that Proxima is not gravitationally bound and thus moving along a hyperbolic trajectory with respect to Alpha Centauri AB", after all, earlier in the paragraph.

Confusing Part of Talk Page[edit]

Wouldn't it be better if the reference at the bottom of this talk page were put into its own section? It's kind of confusing to have it be right there, without even a full line break to separate it. Honestly, before I figured out it was someone else's reference, I thought I had somehow put a link in my post. Seems like just putting it in a separate References section would be an easy solution to an annoying minor issue, that's all. :/ — Preceding unsigned comment added by SarahTehCat (talkcontribs) 00:34, 22 August 2015 (UTC)

Rewrite the lede[edit]

The lede seems to WANT to be confusing. AC is a binary system of 3 stars? No, its not. The system appears as a single VISIBLE star (to the naked eye) with two stars contributing to its VISIBLE brightness. The first paragraph of the Nature and Components section does a better job at introducing the subject than the contradictory lede. Alpha Centauri may refer to the stellar system (gravitationally bound, composed of two or probably 3 stars as well as possibly one or more planets (although the latter fact has been recently questioned). And it refers to a visible sky object, a "star". In addition, I wonder if it is established FACT that it is closest to Earth (that is, that Proxima Centauri is), rather it is the closest star KNOWN. (I believe there was some work published in the last year or two placing some constraints on the existence of stars near-by that have remained as yet undetected - possibly down to the brown dwarf category, which are generally not considered "stars".) Anyway, Alpha Centauri may refer to the visible star or the star system. The visible star is composed of two stars and Proxima Centauri, Alpha Centauri-C, is probably the third star in that star system but, although we predict it to be gravitationally bound, it is not visible to the naked eye so not part of the visible star. And please remove the backward phrasing of its relative brightness (note: "relative") when its described as "only fainter than". Use plain English. Only two stars in the night sky appear brighter. But you should also note that it is a Southern Sky star, and not visible from above latitude X in the Northern Hemisphere, and that it is therefore normally the second brightest star in the southern sky, after Canopus, and is part of the constellation Centaurus. (Not sure what X is, 45° ? ) Any reference to brightness should always clarify that it is apparent brightness, not absolute magnitude, that we are talking about, imho. Perhaps I'm being too picky there.216.96.76.79 (talk) 08:29, 30 August 2015 (UTC)

Ok, I tried rejigging it like so. I think we can leave out "closest known star" as it is extremely unlikely anything larger than a small brown dwarf (and hence nonstellar) will be found. Cas Liber (talk · contribs) 10:02, 30 August 2015 (UTC)
(edit conflict) Let's see: 1) Alpha Centauri is a system consisting of three stars, A, B, and C (Proxima), which is most likely gravitationally bound and, if not, is still associated with A–B. The point of light in Earth's sky is just a consequence of the existence of this stellar system and article's are about stars and stellar systems, not 'points of light in Earth's sky', which is not something distinct, but simply what we can see of it with the naked eye here. 2) There are no stars or brown dwarfs closer to the Sun than Proxima, else WISE would have detected them (it has even ruled out Tyche).
You're quite right, though, that it should be crystal clear at all times whether something is the apparent or absolute magnitude. I have improved this. --JorisvS (talk) 10:20, 30 August 2015 (UTC)
There is a problem with all this. The implication now in the lead is that Proxima contributes to what is seen with the naked eye. It doesn't. It would be clearly separated from AB if it were actually visible to the naked eye. The "point of light" that is seen is not even marginally affected by Proxima's feeble light. This is actually explained, quite well I thought, further down the article. To give you some context the article itself describes the separation as "four times the angular diameter of the full moon", not even close. Lithopsian (talk) 13:11, 30 August 2015 (UTC)
Aah. good point. Will sleep on it as midnight here. Cas Liber (talk · contribs) 14:02, 30 August 2015 (UTC)
Proxima Centauri has its own featured article. It is probably best to treat it as a separate object, with a mention that it might be physically associated. It is two degrees away from Alpha Centauri, over a fifth of a light year away. I gave this a quick look over when the original talk posting was made and I thought the lead was reasonably informative and accurate. Perhaps it doesn't make sense to go back after all the improvements today, but certainly worth a look back at that version with a new point of view. Lithopsian (talk) 19:33, 30 August 2015 (UTC)
Why? It is most likely part of the same system. Just because it happens to be so close it can be seen far from AB. Of course because we have the separate article, we do not need to cover it in more detail than just a summary. --JorisvS (talk) 10:28, 31 August 2015 (UTC)
The problem is that the lead now implies (actually states pretty strongly) that while Alpha Centauri appears as a single naked eye object, it consists of three stars. It doesn't. The system may (or may not) gravitationally consist of three stars, but visually Alpha Centauri consists of A and B, seen as a single object without considerable optical assistance. We shouldn't claim that a star two degrees away, regardless of what that translates to in physical distance, is part of that naked eye object. Lithopsian (talk) 10:38, 31 August 2015 (UTC)
You're right about that, of course. The problem is in the definition, which is currently a looking-at-the-sky approach. I'll take a crack at it. Let's see what we can make of it. --JorisvS (talk) 11:12, 31 August 2015 (UTC)

Apparent magnitude, -0.27 or -0.29?[edit]

Few scientific papers or catalogues quote a combined visual apparent magnitude for Alpha Centauri AB. Instead there are separate values for A and B. The combination is a well-defined mathematical operation, and I don't think it contravenes WP:NOR. Until recently, this article showed the value -0.27, with a reference to Burnhams Celestial Handbook (it is on page 549). Burnham also gives individual magnitudes for A and B, at -0.04 and +1.17 respectively. Unfortunately that doesn't combine to -0.27. Coincidentally (?), the individual magnitudes shown in the article were +0.01 and +1.33, which do combine to -0.27. These values were not cited, but do match the values currently at Simbad, derived from Ducati 2002.

So far, so good. Then I came along and added references for the individual magnitudes. I used the Bright Star Catalogue since I was looking at it for the Brightest Stars List article. It is an older source but widely referenced. The A and B values were -0.01 and +1.33, combining to -0.29. User:JorisvS changed the combined value to -0.27 (with a web-page citation), but not the individual magnitudes. This edit got overwritten by some subsequent edits, so it now says -0.29 again and is consistent with the individual magnitudes. However there is a case for using the newer reference and going back to -0.27, with individual magnitudes of +0.01 and +1.33. I generally use the newest available dedicated photometry, which is usually what Simbad links to, in this case Ducati 2001.

Any thoughts? Lithopsian (talk) 13:31, 1 September 2015 (UTC)

I just saw that the source cited then did not give the combined value. Looking for a citation, I found one at the German Wikipedia, but that says −0.27, so I changed it. I'm fine with using a newer reference for the individual values and −0.29, as long as a note is added explaining the required calculation. --JorisvS (talk) 15:04, 1 September 2015 (UTC)
Well that ended up being a lot of work. Turned out much of the starbox data was out of date or not referenced, and there were several formatting problems. Should all be fixed, but definitely worth checking over. I used Ducati 2001, A=+0.01, B=+1.33, combined magnitude -0.27. Lithopsian (talk) 16:44, 1 September 2015 (UTC)

Starbox image[edit]

What is that? Does that tell anyone anything? It isn't even nice eye candy. Surely we can do better. Lithopsian (talk) 16:46, 1 September 2015 (UTC)

Gone. Replaced with something hopefully more informative, as well as quite attractive. Lithopsian (talk) 14:50, 3 September 2015 (UTC)

How far away is Alpha Centauri?[edit]

Seems like there should be a well-known and widely-accepted value, but it appears not. Recent research papers quote various values from 1.33 pc to 1.35 pc, or just 1.3 pc or 1.4 pc. This isn't an entirely trivial difference for such an important star. The table in the article summarises the relevant parallax measurements. The most import are: Perryman (1997) ,the original Hipparcos reduction; Söderhjelm (1999), a refinement of the original Hipparcos reduction using binary orbit data; and van Leeuwen (2007), the new Hipparcos reduction. The Söderhjelm reduction is the most widely cited value, and was certainly the most reliable prior to 2007. However, even after 2007, the new Hipparcos reduction is largely ignored. Unfortunately I couldn't find a single source that says why, so I don't know if there is a good reason why Söderhjelm is preferable or if lazy researchers are just cut'n'pasteing from the last paper they wrote. Söderhjelm makes useful refinements to the original Hipparcos reduction and obtains an impressively small margin of error, but obviously doesn't take into account the systemic sources of error analysed in the new Hipparcos reduction. The existence of unaccounted for sources of error in at least some reductions is clear from the non-overlapping error ranges of the various reported parallaxes. Right now this article contains the van Leeuwen (2007) parallax values, including the rather inaccurate separate value for component B (not calculated in other reductions due to the known inaccuracy), and the plain distances derived by the starbox. That means component A shows a distance somewhat smaller than most other sources (eg. 4.32 ly vs 4.37 ly) while component B is showing a clearly aberrant distance of 4.1 ly. Seems like at least the component B value should be forced manually to something sensible, perhaps with a footnote? Lithopsian (talk) 15:20, 3 September 2015 (UTC)

Since the two components orbit one another, shouldn't they both have a range of distances for the Earth? Kortoso (talk)
The orbit is tiny by comparison, less than 0.001 light years across. Lithopsian (talk) 22:27, 1 October 2015 (UTC)

New data[edit]

A paper published in January 2016 revises the parallax, masses and orbital parameters: Parallax and masses of α Centauri revisited⋆ Dimitri Pourbaix1,⋆⋆ and Henri M. J. Boffin. Should we update the article with the new numbers?--agr (talk) 12:38, 28 August 2016 (UTC)

Inclination?[edit]

The Infobox states that the inclination is "79.205 ± 0.041°". It appears to indicate that this is the inclination for both A and B components. Is that likely? I have to assume that this is the value for A and that the inclination for B is missing.

Or am I missing something?12.222.8.178 (talk) 18:32, 28 October 2015 (UTC)

It refers to the orbit. By definition, an orbit with two components is in a plane, that entry is defining the inclination of that plane. Tarl.Neustaedter (talk) 19:28, 28 October 2015 (UTC)
So it refers to the orbit of A around B and vice versa. Thanks! Kortoso (talk) 19:51, 28 October 2015 (UTC)

GA Review[edit]

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

Reviewer: Jens Lallensack (talk · contribs) 18:37, 17 January 2016 (UTC)


I will review this. --Jens Lallensack (talk) 18:37, 17 January 2016 (UTC)

Looking good. Here are my comments so far:

  • link "flare"
  • some information in the article come without citations. Information needs to be verifiable according to the GA criteria. Would it be possible to add additional citations?
  • The projected rotational velocity ( v·sin i ) is 1.1 ± 0.8 km·s−1, resulting in an estimated rotational period of 41 days. (An earlier, 1995 estimate gave a similar rotation period of 36.8 days.) – A minor thing here: I would suggest to remove the brackets, and to add date and source for the more recent estimate.
  • Section "Nature and components": Alpha Centauri A and B are both summarized, but Alpha Centauri C is lacking information. Yes, the info can be found within the article Proxima Centauri, but for comparisons it would be good to include the same information that is given for the other two stars (luminosity, rotational period etc.).
  • best replace Gyr with "billion years", enhancing comprehensibility.

more will follow. --Jens Lallensack (talk) 19:23, 17 January 2016 (UTC)

I've only just taken a quick look. The first thing that caught my eye was the "Alpha Centauri AB distance estimates" section. The presence of the table seems to lack context and I'd like to see a brief text introduction. A casual reader might wonder: why is the table here and what does it mean in plain English. Searching the text I saw "As the stars of Alpha Centauri approach us, the measured proper motion and trigonometric parallax slowly increase." Including a table like this implies to me that it illustrates some significant trend over time, but the data doesn't support the text statement. --mikeu talk 01:09, 19 January 2016 (UTC)

The stellar distance estimates tables have been discussed before, and opinions were mixed. The data is a direct reflection of the improvements in parallax measurement technology and doesn't tell the reader anything useful about the star system itself. A few people seem to find them of value; I don't. Praemonitus (talk) 21:00, 27 January 2016 (UTC)

The "View from this system" and "View from a hypothetical planet" sections seem a bit long and lack citations. Have these topics been discussed at length in reliable sources? Is the material notable enough to warrant extensive discussion in the article? Those are longer than "Observational history" which contains more important information (early parallax measurements) giving these sections undue weight to a topic of more trivial importance. --mikeu talk 02:10, 19 January 2016 (UTC)

The main picture seems to be of Alpha Centauri and Beta Centauri, not Alpha Centauri A and Alpha Centauri B, according to its own caption. ?Jientho (talk) 19:06, 26 January 2016 (UTC)

Query[edit]

Jens Lallensack, where does this nomination stand? The nominator, Marenello Prime, has not edited on Wikipedia since January 7, the day this article was nominated. Given that there hasn't been any response there, either someone needs to be willing to take over the task of making the necessary fixes to the article, or the nomination should probably be closed. BlueMoonset (talk) 22:30, 8 February 2016 (UTC)

You are right. I closed the nomination due to inactiveness of the nominator, in the hopes that he will resume working on the article and nominate it again once it's in shape. --Jens Lallensack (talk) 08:32, 9 February 2016 (UTC)

Age[edit]

The source used to cite the the ages of A and B, has two very different ages for A and B, which are now also in the infobox. I would expect A and B to be the same age. Is it realistically possible for the two components of a fairly close binary to have such drastically different ages? --JorisvS (talk) 11:56, 17 February 2016 (UTC)

As I read that article, I understood it to propose a method for calculating ages, but it has large error margins, and does not claim certainty. I find the below paragraph particularly relevant, about table 13, where t1 and t2 for A and B are 6.6/4.2 (A) and 5.2/6.5(B).
Estimated ages using our methods are listed in the final two columns of Table 13. The first column of ages ( t1 ) are from using the revised activity-age relation (x 3.2.2, eq. [3]). The second column of ages ( t2 ) are those inferred from converting the chromospheric activity levels to a rotation period via the Rossby number and then converting the rotation period to an age using the revised gyro relation (x 4, eqs. [5] Y [8] and [10] Y [12]). The final column of ages t2 are the preferred age estimates. The inferred activity age for the extraordinarily active zero-age MS star AB Dor is 1 Myr and clearly in error (apparently by 2 orders of magnitude; Luhman et al. 2005). As AB Dor painfully illustrates, the uncertainties in the inferred ages for the very active stars (log R0 > HK 4:3) are large ( 1 dex; e.g., Table 9). A conservative estimate of the typical age uncertainty is 50% for the preferred ages of the lower activity stars.
As I understand it, at best, those ages are inaccurate to within 50%, certainly not enough to claim the stars were created at different times. Tarl.Neustaedter (talk) 00:42, 21 February 2016 (UTC)
Giving these values without uncertainties is extremely misleading, because we can indeed expect them to be the same age. I don't know if we can use the current source properly for that; they give such a top-of-the-head figure. Do you? Else, we should try to find a different article. --JorisvS (talk) 09:16, 21 February 2016 (UTC)

Toliman[edit]

I had a hard time figuring this out, but Tolimân is apparently Golius' (1669) rendition of what Al-Farghani mentions as a native Arabic name of the Centaurus constellation, apparently (not translated by Golius but according to Kunitzsch 1961) corresponding to ظلمان Ẓulmān "ostriches". Note that neither Al-Farghani nor Golius give this as a name of the star Alpha Centauri, it is mentioned as an alternative name of Centaurus. It is unclear when and where this was first used as a name for the star, but Kunitsch in the 1976 article states that according to his knowledge, this alternative name had only currency in German-language literature, so I'm going to assume it came up in the 1960s in German astronomical almanacs and/or astrological literature. Indeed, all pre-1990 references known to google books are German. The earliest mention of the name in English-languge literature to be found dates to 1992.[12] Also, the entire role of this name in English or German literature is "here is a list of alternative names of Alpha Centauri". Nobody actually ever uses this as an actual name to refer to the star. It seems to be part of a 1990s fashion to give as many "multicultural" names of stars as humanly possible. --dab (𒁳) 15:38, 8 May 2016 (UTC)

actually, correction: there is an opaque tradition of English-language references invoking a fake Hebrew etymology of the name. This was apparently the original idea of one Frances Rolleston in a work called MAZZAROTH, or, the CONSTELLATIONS published in 1863. This never comes up in actual astronomical literature, which seems to import the name from German, but it shows up now and again in Hebrew-mysticism/occultist literature. --dab (𒁳) 15:41, 8 May 2016 (UTC)

Sun and constellations viewed from Alpha Centauri[edit]

The section about the night sky seen from AC states that "Sirius lies less than a degree from Betelgeuse in the otherwise unmodified Orion", but if one checks with the simulation picture of this night sky, Orion actually looks quite tilted. Relative to Orion's Belt, Betelgeuze is roughly where Bellatrix would be seen from Earth, and the inclination of the belt looks fairly different, too. It's as if our starry Giant has been tilted, even wrung around (compare with any normal map/sketch of Orion and you'll see what I mean).

This is puzzling because the lead stars in Orion are much more distant than many other in the night sky, so the whole figure shouldn't be that much affected by a distance of four light years on the end of the viewer. Bellatrix is almost three times closer than Betelgeuze, but it's still hard to see that this would make much difference to its position in the sky (it's still 240 light years away) and change the constellation in this way. The belt stars are farther away than either of them. Strausszek (talk) 03:53, 20 August 2016 (UTC)

What you're noticing (the stretching effect) is almost certainly the result of projecting a spherical surface onto a flat screen - fitting both the Sun and Sirius into the image results in serious spherical aberration away from the center of the projection. You are correct, Orion's stars are so far away that from Alpha Centauri, that constellation would look almost un-altered. If you want to see Orion as it would be seen from there, you'd have to get Celestia and re-project that image centered on Orion, rather than having it off to the side of the image. Tarl N. (discuss) 04:10, 20 August 2016 (UTC)
Ahh, projection distortion! Just like in most maps of a large chunk of the earth's surface (South America, New Zealand and Australia can look really weird on some world maps). You're right of course, I just didn't realize that the section of the sky in the picture was so large and that Orion was in a corner. Since it's on the celestial equator of the sky (at least viewed from Earth) unconsciously one expects it to come out "right" in any map. Thanks: Strausszek (talk) 15:31, 20 August 2016 (UTC)

Revised masses[edit]

To whomever maintains this article:

"The components are thus a bit more massive than previously thought (1.13 and 0.97 M⊙ for A and B, respectively). These values are now in excellent agreement with the latest asteroseismologic results."

Per:

Pourbaix, Dimitri; Boffin, Henri M. J. (February 2016), "Parallax and masses of α Centauri revisited", Astronomy & Astrophysics, 586: 4, arXiv:1601.01636Freely accessible, Bibcode:2016A&A...586A..90P, doi:10.1051/0004-6361/201527859, A90. 

Praemonitus (talk) 15:02, 31 August 2016 (UTC)

Redundant sentence[edit]

The article says, " Because the distance between the Sun and Alpha Centauri AB does not differ significantly from either star, gravitationally this binary system is considered as if it were one object."

This describes all true binary systems, and it does not explain any important property of Alpha Centauri. 2600:1000:B11B:79CF:69F0:EA5B:67C9:8A79 (talk) 15:17, 27 September 2016 (UTC)

This is in the second paragraph of Alpha Centauri#Nature and components, in a discussion of why designations often consider "C" a separate object, but A&B are generally listed as a single object. It's a clumsy statement, and could certainly stand re-wording, but the essence is that for practical purposes the C component is often listed as a separate object (it's objectively nearer and has a really wide angular separation), while the AB components (like most binary stars) are usually listed as a single object together. Any good ideas on how to rephrase it? Tarl N. (discuss) 16:02, 27 September 2016 (UTC)

Binary system[edit]

Some of the text in this section (https://en.wikipedia.org/wiki/Alpha_Centauri#Binary_system) is redundant. For instance:

From the orbital elements, the total mass of both stars is about 2.0 M☉—or twice that of the Sun. The average individual stellar masses are 1.09 M☉ and 0.90 M☉, respectively, though slightly higher masses have been quoted in recent years, such as 1.14 M☉ and 0.92 M☉, or totalling 2.06 M☉. Alpha Centauri A and B have absolute magnitudes of +4.38 and +5.71, respectively. Stellar evolution theory implies both stars are slightly older than the Sun at 5 to 6 billion years, as derived by both mass and their spectral characteristics.

This is repeating previously stated information and adds nothing to the discussion at this point. Is this a merge artifact?
Then we have a report from an apparent time-traveler:

The closest approach in the future was in February 2016, at 4.0 arcsec through 300°.

Alpha Centauri A/B and Proxima Centauri are truly a bound system![edit]

According to this source[1], Alpha Centauri A/B and Proxima Centauri are truly a bound system, with an orbital period of ~550,000 years. -- JP — Preceding unsigned comment added by 75.163.75.97 (talk) 21:18, 2 December 2016 (UTC)

References

Requested move 27 December 2016[edit]

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: Not moved per WP:SNOW (non-admin closure) Fuortu (talk) 17:37, 27 December 2016 (UTC)


Alpha CentauriRigil Kentaurus – per International Astronomical Union, officially renaming it as Rigil Kentaurus, at https://www.iau.org/public/themes/naming_stars/ SkyFlubbler (talk) 07:53, 27 December 2016 (UTC)

  • Oppose. This is one of the best-known stars in the sky. The IAU announced this rename a month ago. We can wait to see if commonly consulted reference works follow suit or not. Pandas and people (talk) 08:55, 27 December 2016 (UTC)
  • Oppose. Rigil Kentaurus and Toliman have been old proper names for it anyway, so nothing has really changed. 99% of occurrences will still be for Alpha Centauri. Cas Liber (talk · contribs) 10:03, 27 December 2016 (UTC)
  • Oppose You have to be kidding? Alpha Centauri has to be by far the most common name. Fyunck(click) (talk)
  • Oppose per WP:Common name. Huntster (t @ c) 10:31, 27 December 2016 (UTC)
  • Oppose per WP:COMMONNAME. Objects have multiple names, the Wikipedia uses the most commonly used as the article name. Tarl N. (discuss) 12:44, 27 December 2016 (UTC)
  • Oppose because Alpha Centauri is one of the most commonly known stars in the sky and nobody is going to start referring to it as Rigil Kentaurus just because the IAU made it the offical technical name (WP:COMMONNAME) MarkiPoli (talk) 12:46, 27 December 2016 (UTC)

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Rigil Kentaurus in lead[edit]

The IAU list from the !vote above of course refers to "Rigil Kentaurus", but my interpretation of it suggests that this would only apply to a Cen A, not the whole system. Perhaps the Rigil Kentaurus reference should be moved to the second sentence and be parenthetical to a Cen A, just as Proxima Centauri is parenthetical to a Cen C, which would render the second sentence to read: "It consists of three stars: the pair Alpha Centauri A (also named Rigil Kentaurus) and Alpha Centauri B together with a small and faint red dwarf, Alpha Centauri C (also named Proxima Centauri), that may be gravitationally bound to the other two." Or, if the term should refer to the AB system, it could read "It consists of three stars: the pair Alpha Centauri A and Alpha Centauri B (together also named Rigil Kentaurus) together with a small and faint red dwarf, Alpha Centauri C (also named Proxima Centauri), that may be gravitationally bound to the other two." Thoughts? Huntster (t @ c) 20:00, 27 December 2016 (UTC)

The name Rigil Kentaurus long precedes the knowledge that it was a double star, and as such has always referred to the AB pair (and I've seen references to Rigil Kentaurus A / Rigil Kentaurus B - for example, here, in an article about the renaming). Do we have evidence beyond a text file from someone's personal directory that the IAU intends the name to no longer refer to the pair of stars? It's possible they decided to do that, I haven't seen the minutes from the meetings. Tarl N. (discuss) 21:33, 27 December 2016 (UTC)
It refers to Alpha Centauri A, not the AB pair.[1] I will go ahead and WP:BOLDLY make the appropriate changes to the article. —MartinZ02 (talk) 00:40, 28 December 2016 (UTC)
  1. ^ "Naming Stars". 
Why did the IAU do the rename? "The move was intended to reduce confusion, according to the IAU."[13] If that's the actual reason, I'd say they need to rethink this issue. Pandas and people (talk) 15:48, 29 December 2016 (UTC)
I am cynical about it. Most of the ones in use are standardized anyway (e.g. you very rarely see any spelling other than "Betelgeuse" these days). If anything, the ones I think they should have prioritized on were brighter stars that lacked Bayer or Flamsteed designations and as those damn HD and HIP numbers are impossible to memorise! Cas Liber (talk · contribs) 21:29, 30 December 2016 (UTC)

Twin stars with different ages?[edit]

What we have is completely stupid. They have to be the same age, but the entry says otherwise. And contradicts what the aricle says: it clearly gives a range. --GwydionM (talk) 16:09, 30 December 2016 (UTC)