Talk:Proxima Centauri

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Discussion of being nearest to Sol makes no sense[edit]

"Proxima Centauri has been the closest star to the Sun for about 32,000 years and will be so for about another 25,000 years, after which Alpha Centauri A and Alpha Centauri B will alternate approximately every 79.91 years as the closest star to the Sun" - it is supposed to be nearest to Sol in ca. 25-27,000 years' time, depending on which study one believes. But then it will move further away for several thousands of years (conceivably, for 57,000 years) before it stops being the closest and Alpha A & B take over. — Preceding unsigned comment added by 2.97.119.194 (talk) 21:23, 15 January 2020 (UTC)[]

Do you have sources for that? Lithopsian (talk) 21:30, 15 January 2020 (UTC)[]

Proxima c confirmed; system inclination determined[edit]

https://arxiv.org/abs/2003.13106 SevenSpheresCelestia (talk) 01:00, 31 March 2020 (UTC)[]

I removed "(unconfirmed)" from the entry for Proxima c in the planetary system table. User:Lithopsian then added "(candidate)", with the comment "call it candidate then, all the references do". Planets detected by radial velocity are always referred to as "candidates" whether they are confirmed or not (for example, the discovery paper for Proxima b calls it a candidate), and since Proxima c has now also been detected by astrometry there can be little doubt about its existence. I see no reason to have "(candidate)" in the planetary system table. SevenSpheresCelestia (talk) 22:16, 31 March 2020 (UTC)[]
The paper you link calls it an "exoplanet candidate" in the title and throughout the text. The paper uses the existing candidate orbital parameters and the Kervella et al. (2019) proper motion anomaly of Proxima to constrain the possible orbital parameters of such an exoplanet. It doesn't confirm its existence or say anything about confirming its existence. As soon as you find a paper that calls it a "confirmed exoplanet" or perhaps just "exoplanet" without qualification, then we can call it confirmed. Lithopsian (talk) 15:02, 1 April 2020 (UTC)[]
Will this do? SevenSpheresCelestia (talk) 16:53, 2 April 2020 (UTC)[]
Possible direct imaging detection now. SevenSpheresCelestia (talk) 01:10, 15 April 2020 (UTC)[]

Since Proxima Centauri c has been confirmed, would it be a good idea to give it is own article or wait until there is more information on it? Adauchi (talk) 17:19, 15 July 2020 (UTC)[]

New paper with potential third planet[edit]

https://arxiv.org/abs/2005.12114 SevenSpheresCelestia (talk) 01:31, 26 May 2020 (UTC)[]

I think the relevant quote is We find some evidence for the presence of a second short-period signal, at 5.15 days with a semi-amplitude of only 40 cm·s" (my italics). Reading the article, there are further qualifiers, barely significant and discussing the signal, casts doubt on its planetary origin. This isn't a paper describing a discovery, it's a paper saying "we see something at the edge of our capabilities, but it's probably not a planet". Tarl N. (discuss) 04:27, 26 May 2020 (UTC)[]
Should still be mentioned in the article. SevenSpheresCelestia (talk) 16:29, 26 May 2020 (UTC)[]
Perhaps slightly less marginal than earlier evidence found, back in 2012, for a planet closely orbiting at 5.6 days - https://arxiv.org/abs/1202.2570 (Bottom of section 4.1 "Proxima, a flaring M4V")
Should the article include the words "Proxima d"? I feel like using "Proxima d" in the article gives general readers the false impression that the signal is planetary in origin — however the paper only speculates that it might be a planet. I propose removing "Proxima d" from the article (maybe the infobox also but I'd like opinions on that) and replacing it with a description of the signal. The name "Proxima d" can be mentioned in a note explaining that if the signal is planetary it would be named as such. Supernova58 (talk) 20:47, 8 August 2020 (UTC)[]
I agree, the paper does not describe the signal as "Proxima d", unlike for b and c. It is clear from the paper they are far from convinced it's real and not just a spurious detection:
"However the planetary origin of the signal is far from guaranteed. Though the posterior distributions and the fit look good, the model is only barely significant over the 1-planet model, and no significant peaks at this period show up in the previous periodograms. Section 5 shows an inconsistent presence of the signal across the ESPRESSO wavelengths, which casts doubts on its planetary origin."
I took a similar approach with Lacaille 9352 where there is also a third signal of dubious veracity. We should mention the signals but be clear the authors aren't claiming them to be bona fide planets.ChiZeroOne (talk) 21:37, 8 August 2020 (UTC)[]
Thanks! I'll start working on that! I'm probably going to leave the infobox alone (for now) as it has been edited a bit recently and I want to make sure other editors agree before changing it. In your opinion though, should the infobox "d" entry stay as it is, be modified, or removed entirely? Actually I think I'm going to wait ~24 hours before making any changes related to the potential third planet so that others have time to contribute an opinion as well if they wish :) Supernova58 (talk) 23:31, 8 August 2020 (UTC); edited 23:34, 8 August 2020 (UTC)[]
I think it would be prudent to err on the side of caution and not include this detection just yet. It's not listed in the exoplanet encyclopedia. Praemonitus (talk) 21:06, 9 August 2020 (UTC)[]

Image issue[edit]

the proxima centauri star image is all messed up, have you used an diffrent image for example a sun false color image taken with ultraviolet light? — Preceding unsigned comment added by Unknownverse Productions (talkcontribs) 19:12, 24 September 2020 (UTC)[]

I don't see anything wrong with it. It's a star image showing diffraction spikes, which is normal for the brightest star in the field of view. What's the problem? Tarl N. (discuss) 21:40, 24 September 2020 (UTC)[]
Not a particularly informative or attractive image though, just an over-exposed dot. Perhaps something like this would be better for the main image? The orbital plot already in the article is another possibility. Lithopsian (talk) 13:14, 25 September 2020 (UTC)[]
Lithopsian, I like your suggested image. It adds a bit of perspective on Proxima's tiny relationship to Alpha Centauri. Attic Salt (talk) 19:16, 25 September 2020 (UTC)[]
It's a nice image true, but at the normal WP size it's impossible to view the little circle. All we're really seeing then is Alpha Centauri. Praemonitus (talk) 19:25, 25 September 2020 (UTC)[]
Perhaps we could add an arrow to highlight Proxima's location? TheWhistleGag (talk) 05:34, 27 September 2020 (UTC)[]
There are several image in Commons with markers pointing out Proxima. Lithopsian (talk) 10:17, 27 September 2020 (UTC)[]

Origin and age[edit]

Proxima was a pre-existing star that was captured by the Centauri A.

https://www.researchgate.net/publication/316193303_The_Composition_and_Evolutionary_Status_of_Proxima_Centauri

Hcobb (talk) 19:53, 4 January 2021 (UTC)[]

Yes, this hypothesis is mentioned in the article. Praemonitus (talk) 22:54, 4 January 2021 (UTC)[]
What isn't mentioned is the recently measured age and composition. Hcobb (talk) 02:29, 6 January 2021 (UTC)[]
It's rather indirect evidence, since the composition is being derived rather than directly measured. But yes it's probably still worth a mention in the same paragraph. Praemonitus (talk) 18:19, 6 January 2021 (UTC)[]

I attempted to add the following comment:

A 2017 study used evolutionary models to estimate the metallicity of this star, and found a composition that differed significantly from that of the Alpha Centauri pair: −0.5 < [Fe/H] < −0.3. The result is more consistent with an age of 7 to 8 Gyr, suggesting an independent origin.

with this reference:

Beech, Martin; et al. (January 2017). "The Composition and Evolutionary Status of Proxima Centauri". American Journal of Astronomy and Astrophysics. 5 (1). doi:10.11648/j.ajaa.20170501.11.

but received a Wikipedia warning:

Warning: An automated filter has identified this edit as introducing references to a predatory open access journal or publisher. Predatory open access publishing is considered self-publishing due to lack of peer-review and predatory journals are rarely, if ever, appropriate for inclusion in Wikipedia. If you are confident that you want to cite this source anyway, please click 'Publish changes' again. Note that citations to predatory journals are routinely removed.

Thus I'll have to oppose adding that. We'll need a better reference. Praemonitus (talk) 19:44, 6 January 2021 (UTC)[]

American Journal of Astronomy and Astrophysics. Lithopsian (talk) 19:49, 6 January 2021 (UTC)[]
Well that probably explains why the paper wasn't included on the SIMBAD page. Interestingly, the paper by Beech et al. (2017) was referenced by the Feng & Jones (2018) cite already used in this article. Their comment:
The question of the evolutionary history of the alpha Centauri system and in particularly the metallicity for Proxima has been recently addressed by Beech et al. (2017). They find a best match for Proxima to have a metallicity of [Fe/H]= −0.5 or by constraining a simultaneous fit with the values of mass and radius used by Kervella et al. (2017) a metallicity of [Fe/H]= −0.3. However, there are a number of uncertainties involved and a metallicity as high as solar is allowed within their one-sigma error bars when considering a mass-radius relationship based on absolute K magnitude. There are a number of recent derivations of spectroscopic metallicities for Proxima showing a spread around a solar-like value, e.g., -0.07±0.14 (Passegger et al. 2016), 0.05±0.20 (Kervella et al. 2016a).
Praemonitus (talk) 22:25, 6 January 2021 (UTC)[]

Confirmed vs. Unconfirmed[edit]

Since Proxima c hasn't been clearly detected, its not officially confirmed, it's regarded as unconfirmed and needed to be edited to be a member of unconfirmed exoplanet candidates. Proxima c is just a strong candidate that has yet to be officially confirmed. — Preceding unsigned comment added by 71.214.105.58 (talk) 15:57, 24 June 2021 (UTC)[]