Talk:List of largest stars

V1804 Sagittarii

Could someone do some research on the star V1804 Sgr, a possible M9.1Iap supergiant star? I'd like to know if it's a RSG, and if it has a size estimate. Nussun05 (talk) 18:02, 23 September 2020 (UTC)

AGB star, probable Mira variable. Very little data on its properties. Spectral class given as M9.5 here with reference to a previous class of M9.5 Iap. No published parallax, distance unknown, hence luminosity and radius unknown. Lithopsian (talk) 19:55, 23 September 2020 (UTC)

This article: http://articles.adsabs.harvard.edu/full/2009ASPC..412..113W/0000113.000.html, states that it is an 'extreme supergiant'. That might be a start?PNSMurthy (talk) 01:55, 24 September 2020 (UTC)

Extremely cool. You're going to struggle to find enough material for an article, though. Lithopsian (talk) 08:53, 24 September 2020 (UTC)

True.PNSMurthy (talk) 10:49, 24 September 2020 (UTC)

So, with the release of Gaia EDR3 V1804 Sgr now has a parallax of 0.9465 mas, however, the astrometric noise values seem to be high. Nussun05 (talk) 17:34, 3 December 2020 (UTC)

Nothing has changed really. Still a very cool star, probably not all that far away, probably not particularly luminous, but what are you going to do with that information? There is no published luminosity, no published radius, and no valid way for us to calculate either for Wikipedia. The DR3 parallaxes themselves can probably be inserted to a number of articles, all interesting stuff, but until someone publishes papers based on it, probably not very relevant to this article. Lithopsian (talk) 21:57, 3 December 2020 (UTC)

Can't find that parallax anywhere, not even in Simbad or Google. Do you have a ref for that? 2A01:E0A:47A:F100:D96C:16C2:E87C:950D (talk) 12:16, 4 December 2020 (UTC)

VizieR entry. Lithopsian (talk) 15:04, 4 December 2020 (UTC)

Mohomous — Preceding unsigned comment added by 84.71.59.189 (talk) 09:34, 3 February 2021 (UTC)

VY CMa

I though VY CMa had a radius of 1400 Rsol, now why is it near 2000? (btw, on both this page and its own page)--WRMetacat108 (talk) 14:00, 17 November 2020 (UTC)

I found a newer source than that 1420 Rsol, which gives 2,069 Rsol Nussun05 (talk) — Preceding undated comment added 17:00, 17 November 2020 (UTC)

If Stephenson 2-18 were to be downscaled before any other star surpasses VY Canis Majoris or before it downsizes, VY Canis Majoris just may have the chance to be the largest star even just one last time. — Preceding unsigned comment added by V255 Canis Majoris (talk • contribs) 17:13, 23 November 2020 (UTC)

The only way this could be the case, is if another reference is found, which gives Stephenson 2-18 a lower radius, or if a new paper is published, which gives Stephenson 2-18 a smaller radius. For nostalgia purposes, seeing VY Canis Majoris back on top would certainly be pleasing to me. For now, however, 2,150 R_☉ is the only value given for Stephenson 2-18. Faren29 (talk) 21:05, 24 November 2020 (UTC)

I would love to see vycma as the largest star again. — Preceding unsigned comment added by 84.71.59.189 (talk) 08:58, 3 February 2021 (UTC)

New Largest Star

I'm definitely suspicious about the star from the Andromeda galaxy that tops this list. It size seems extreme (and most likely inaccurate). I don't think intergalactic stars with such inaccurate estimations should be included since they have large margins of error. It's extremely hard to predict the sizes of such distant objects, and most of their predicted sizes do not hold. I know I've raised this concern previously but I really think all intergalactic stars' sizes should be looked into.PNSMurthy (talk) 01:25, 31 January 2021 (UTC)

I tried to search for the star in SIMBAD, and apparently there is not much data regarding this object. There is not even data about its spectral type, temperature, or even the apparent magnitude. The only designation it has is the clumsy 2MASS Extended one, and its coordinates.

We need to be very suspicious about adding extragalactic stars in this list. Unless otherwise notable and well-cited (such as WOH G64), I would be quite hesitant to accept that they should be on this list, especially if they are just known in complicated catalogues. SkyFlubbler (talk) 06:08, 31 January 2021 (UTC)

Agreed. We shouldn't blindly add stars with extreme radii, but first see if other sources support the said star, and if the radii is in the realms of believability.PNSMurthy (talk) 03:43, 1 February 2021 (UTC)

Semi-protected edit request on 3 February 2021

Hey wikipedia, Vycma's size is uncertain but right now it's radius is about 2069 so it would be higher on the list. Also I just want vycma to be higher due to nostalgia. https://astronomical.fandom.com/wiki/VY_Canis_Majoris this website also states the fact that vycma's radius is 2069. 84.71.59.189 (talk) 08:52, 3 February 2021 (UTC)

 Not done for now: please establish a consensus for this alteration before using the {{edit semi-protected}} template. It looks like this issue has been discussed before on this talk page, and the best estimate we have for the radius is listed correctly in the article already; you can have a look at VY Canis Majoris as well if you'd like. If you still think there is an issue you can discuss it on the take page and try and establish a consensus for the change. Volteer1 (talk) 10:24, 3 February 2021 (UTC)

I think the size is mentioned on the list, but we're using a smaller estimate because its more reliable when compared to other stars and estimates.PNSMurthy (talk) 07:30, 4 February 2021 (UTC)

All stars from Ren et al 2020

Can someone add all the remaning stars from the Ren et. al. source? Thanks in advance. Nussun05 (talk) 20:57, 17 February 2021 (UTC)

Could you please link the paper here?PNSMurthy (talk) 07:16, 18 February 2021 (UTC)

https://arxiv.org/abs/2006.06605 here you go Nussun05 (talk) 07:58, 19 February 2021 (UTC)

Thanks!PNSMurthy (talk) 08:16, 19 February 2021 (UTC)

I have checked the paper and the table at the DOI link, and I do not recommend to add the stars to the list. We are not sure about the accuracy of the measurements simply because these are extragalactic stars that are too far away in order to obtain proper results (there is even one star listed at the table for the LMC with 13,127 R_⨀). Though most of the stars I see on the list are within the range of some well-established RSGs here in the galaxy, the existence of data like this one makes me skeptical about using this source at all. SkyFlubbler (talk) 08:45, 22 February 2021 (UTC)

Yeah, extragalactic stars in general are harder to measure because we don't know if they're a part of their apparent galaxy or not. Maybe we should just not include these sizes at all? Nussun05 (talk) 18:36, 22 February 2021 (UTC)

I would not recommend using this source at all, even for stars that may look like having acceptable sizes (most of the stars in the source are of ~700 solar radii). We should look carefully at the method on how they measured their diameters before putting them in this list. Most of these stars have their sizes measured using SBL via temperature-luminosity function, and while this method may be acceptable for stars within our galaxy (St2-18's size was actually derived using this method), I would not recommend it for extragalactic stars since it has proved to be having a lot of issues to be acceptably useful. I would rather pick up on the sizes of extragalactic stars if it was based on interferometry (say WOH G64, measured by the VLT) which is more reliable. Unless we find another source that measures the sizes of those stars via interferometry, I would not see any star on Ren et al's source to be included in the list of largest stars anytime soon. SkyFlubbler (talk) 07:32, 26 February 2021 (UTC)

Its not that all sources including extragalactic stars should be disregarded. Many papers publishing the sizes for the aforementioned stars are reliable and valid. Yet the sizes in this paper - now that I've looked at it, do seem a bit dubious. How on earth did they get 13,000 _⨀ for a star?PNSMurthy (talk) 22:20, 27 February 2021 (UTC)

It's not like I'm saying that all sources discussing about extragalactic stars should be thrown off. There are special cases where we could consider extragalactic stars based on what method is being used, and how they are verified by multiple sources. By the looks of the paper by Ren et al, I would be extremely skeptical about adding it. SkyFlubbler (talk) 04:36, 28 February 2021 (UTC)

I guess we should remove the stars already present from this source? Nussun05 (talk) 05:05, 28 February 2021 (UTC)

Delete Stephenson 2-18 from the list?

The source [1] for Stephenson 2-18 being 2,150 solar radii says on pp11-12 ‘Unfortunately, at this moment, the distance information is based on radial velocities (i.e., distances are estimated by assuming the flat rotation model of the Galaxy). Therefore, the distances could include a relatively large uncertainty (relative error of more than 50% according to the recent results of trigonometric parallax measurements; H. Imai 2012, private communication; theoretically, however, the distances to massive clusters may be improved in the future, because there are independent methodologies to measure the distances to clusters (see, e.g., Perryman et al. 1998; An et al. 2007)).’

This indicates that there is a high degree of uncertainty in the size of Stephenson 2-18, so would it not make sense to take it off the list until further, more accurate observations have been made?

SpaceImplorerExplorerImplorer (talk) 16:49, 14 March 2021 (UTC)

Almost every star on the list has some level or the other of uncertainty. It would be unfair to pick and crop this one alone. I think we should le forve it where it is until further evidence is uncovered for or against it.PNSMurthy (talk) 09:03, 15 March 2021 (UTC)

I have "finished" the list

I'm working on trying to complete and improve the general quality of the list here: https://en.wikipedia.org/wiki/User:Nussun05/Finishing_the_list_of_largest_stars. What do you all think and should it be replaced with this? Nussun05 (talk) 17:06, 16 April 2021 (UTC)

Hi, sorry for what I did to you last time but it looks great.--The Space Enthusiast (talk) 06:17, 19 April 2021 (UTC)

Looks great! There are some things from there that can be added here probably.PNSMurthy (talk) 08:48, 1 May 2021 (UTC)