Talk:List of largest stars

On 10 May 2024, it was proposed that this article be moved to List of largest known stars. The result of the discussion was not moved.

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MU Cephei

972 R_☉ should be added back to the Mu Cephei entry. The reason to remove it was solely because the distance is "inconsistent with the OB association where the star is". This is not a convincing reason to remove the whole estimate, Mu Cephei is not a confirmed member of any OB association, it is just assumed based on its position in the sky. Nothing disallows it to be a foreground object, and Jim Kaler even says Oddly, one study shows the star NOT to be a member of the association. Recently the blue supergiant Sher 25 was found to lie in the foreground of its cluster, so the possibility that Mu Cephei is closer than previously believed is not remote. 21 Andromedae (talk) 11:09, 5 October 2024 (UTC)[reply]

Yeah, but the 641 pc distance used for the 972 R_☉ estimate is just based on the 222 pc distance to Betelgeuse but upscaled, which isn't a reliable method of estimating the distance. Plus its extinction is in agreement with the larger ~900 pc distance. Diamantinasaurus (talk) 09:32, 6 October 2024 (UTC)[reply]

As Perin et al. (2005). explains, the extinction reaches a plateau at around 500 parsecs, which encompasses both 940 and 641 pc. Hence the extinction agrees with every distance a bit larger than 500 parsecs. This list isn't strict with reliabilities of star sizes, so adding this estimate is acceptable, and the method used to estimate the distance isn't bad. If Montarges et al. (2019) and Perin et al. (2005) chose this method, there is a reason, of course. 21 Andromedae (talk) 17:02, 6 October 2024 (UTC)[reply]

the reason is that they're both M2 stars, but I don't like this reasoning honestly. W60 B90 is M2, V354 Cephei is M2.5 and MSX LMC 597 is M2.5 and yet all three are over 1200 solar radii.

mu Cephei is M2Ia and Betelgeuse is M1-2Ia-Iab, so their spectral types aren't even that similar. RSGC1-F04 might be M1I too but no one uses Betelgeuse to estimate its distance.

Also, the 640 pc distance uses an overestimated distance to Betelgeuse as well. Diamantinasaurus (talk) 18:57, 7 October 2024 (UTC)[reply]

Mu Cephei is either M1I (infrared spectral type from Levesque et al. 2005) or M2Ia, not so far from Betelgeuse, and it could be even hotter, with a surface temperature of 4,022 Kelvin (see Perrin et al. 2005), perhaps a K-type supergiant. The mass-loss rate of Mu Cephei is also much lower than that of similar-sized RSGs, it is 100 times lower than that of VY Canis Majoris and 10 times lower than that of other red supergiants (Shenoy et al. 2015) far too low for a large RSG with a radius of 1,400 solar units. 21 Andromedae (talk) 20:51, 12 October 2024 (UTC)[reply]

mu Cephei recently had a higher mass-loss rate at around 5 * 10^-6 solar masses per year per the link, which doesn't differ too much from that of several RSGC1 RSGs (RSGC1-F06 has a smaller one, F10 has a similar one, F05 has a similar one, even the extremely luminous F04 has a not much higher one etc.) and the 1,000 - 1,300 R_☉ SU Persei has an even lower mass-loss rate. The 1,245 - 1,520 R_☉ V354 Cephei also has a similar low mass-loss rate. Diamantinasaurus (talk) 21:15, 12 October 2024 (UTC)[reply]

RSGC1 is an extra case. Take RSGC1-F01 as an example, it is larger than VY Canis Majoris, same spectral type and present maser emission, but its estimated mass-loss rate is 33 times lower, pretty pretty odd. The mass-loss rates could have been underestimated as well. SU Persei is could only 800–900 solar radii based on another distance of 2137 parsecs in table 2.1 here. Indeed the mass-loss can't rule out a radius up to 1,200 R_☉, but a very large radius e.g. 1,426 R_☉ is unlikely given the estimated mass loss. 21 Andromedae (talk) 00:01, 13 October 2024 (UTC)[reply]

Fair point for 1,400+ R_☉. Maybe keep it at 1,259 R_☉ then? Diamantinasaurus (talk) 15:32, 3 November 2024 (UTC)[reply]

Why is Stephenson 2 DFK 1 not listed?

Genuine question, why is Stephenson 2 DFK 1 not listed? I've heard that it has a claimed radius of 2.99 billion kilometres, which is also often claimed to be unreliable, I'm mostly confident that that is the reason, but I haven't had confirmation. Newaccount33333 (talk) 22:02, 17 October 2024 (UTC)[reply]

Check through Archive 4, there are a half-dozen threads about the matter. Primefac (talk) 22:08, 17 October 2024 (UTC)[reply]

Consensus in the last year resulted in the removal of this star. In short, the radius of Stephenson 2 DFK 1 is highly unreliable and must not be there. 21 Andromedae (talk) 23:33, 17 October 2024 (UTC)[reply]

The reason why it isn't here is because the distance used to estimate the radius had a >50% uncertainty and it was derived assuming a spherical dust envelope which can often lead to overestimations of the luminosity given that most red supergiant dust envelopes are asymmetric. SpaceImplorerExplorerImplorer 07:27, 18 October 2024 (UTC)[reply]

So yes, in short, unreliable estimates. I appreciate the explanations. Newaccount33333 (talk) 20:08, 19 October 2024 (UTC)[reply]

NGC 1313-310

This star has a bunch of notes for its uncertainty, like for its temperature and its luminosity. For the temperature, it’s the Titanium(II) oxide lines that usually result in higher temperatures, and the luminosity which apparently hasn’t been constrained enough to confirm its large size. To be honest, this just seems like Stephenson 2 DFK 1 but without the distance uncertainty. And that brings the question I want to ask, should it be removed from the list for these reasons? Atlantlc27Lol (talk) 11:21, 31 October 2024 (UTC)[reply]

It does seem like a lot of caveats and addenda. Primefac (talk) 11:52, 31 October 2024 (UTC)[reply]

You could use the T_eff scaling relation in page 13. It's quite uncertain but works very well for other stars with a TiO-derived effective temperature which could make it moderately acceptable. SpaceImplorerExplorerImplorer 16:13, 31 October 2024 (UTC)[reply]

I removed it along with two other stars from the list. The rest are acceptable but those three simply have too many caveats. Faren29 (talk) 14:35, 1 November 2024 (UTC)[reply]

Likely a very good choice. They shouldn’t be placed on the list until they have accurate radii or atleast better radii without as many caveats and potential errors. Atlantlc27Lol (talk) 02:54, 2 November 2024 (UTC)[reply]

I think that gets like 1,500 solar radii for it, iirc. Diamantinasaurus (talk) 15:22, 3 November 2024 (UTC)[reply]

"To be honest, this just seems like Stephenson 2 DFK 1 but without the distance uncertainty."

Isn't distance literally the biggest issue with the large estimate for St2-18? Diamantinasaurus (talk) 15:26, 3 November 2024 (UTC)[reply]

I meant that with the temperature and luminosity Atlantlc27Lol (talk) 15:40, 5 November 2024 (UTC)[reply]

I think that the caveats in the side are already enough. I agree that these stars could be removed but some people still disagree, so it may be better to include them for now. 21 Andromedae (talk) 16:50, 3 November 2024 (UTC)[reply]

PZ Cas

The 1,585 solar radii estimate uses a Gaia distance of 2,586 parsecs, but i’m pretty sure the 2,810 parsec distance is more accurate. Should that estimate be removed? Atlantlc27Lol (talk) 00:12, 12 November 2024 (UTC)[reply]

Keep in mind that in the pdf there is a discrepancy between uniform disc- and limb-darkened disc-derived angular diameters. The UD angular diameter was chosen for other stars and the LDD angular diameter was not shown for this one so its radius may be uncertain. SpaceImplorerExplorerImplorer 10:36, 14 November 2024 (UTC)[reply]

MACS J0647.7+7015 LS1 and LS2

According to this article, https://arxiv.org/pdf/2211.13334

MACS J0647.7+7015 LS1 may be 5-32 million L_☉ with a temperature of 10,000 kelvin, using the Stefan-Boltzmann Law this results in a size of 746.5-1,888.6 R_☉ and MACS J0647.7+7015 LS2 which may be 10-40 million L_☉ with a temperature of 12,000 kelvin, using the Stefan-Boltzmann Law this results in a size of 733.1-1,466.3 R_☉. Should we add this or ignore this? Orangefanta120 (talk) 19:26, 25 November 2024 (UTC)[reply]

Could be affected by microlensing of surrounding stars, making them appear far more luminous as stated in page 7. SpaceImplorerExplorerImplorer 19:08, 26 November 2024 (UTC)[reply]

I also saw an estimate of 316,000-1,000,000 L_☉ in this paper, I'm assuming this is more reliable. Orangefanta120 (talk) 19:22, 26 November 2024 (UTC)[reply]

Smaller radius for AH Scorpii

According to Healey et al. 2023 (the same source that provided the 909 R_☉ measure for UY Scuti), AH Scorpii is calculated to have a radius of 959 R_☉. I believe this is reliable and seems to be a more suitable measure for its spectral class than the 1411 R_☉ measure provided. Should I include that radius on the main page? SamHalls2015 (talk) 18:29, 22 December 2024 (UTC)[reply]

If I remember properly, that table uses Gaia distances which are often unreliable in the case of red supergiants. 1411 R_☉ used a distance that was derived using masers which is much more accurate. SpaceImplorerExplorerImplorer 17:50, 23 December 2024 (UTC)[reply]

This smaller radius uses a distance that is potentially unreliable as mentioned above, while the large radius uses a nearly perfect distance. 21 Andromedae (talk) 17:04, 25 December 2024 (UTC)[reply]

LGGS J013339.28+303118.8

According to Gaia DR3, LGGS J013339.28+303118.8 is actually a blend of up to 3 stars meaning that (to my knowledge) 1566 R☉ is probably innacurate. Should it be removed now? Infa 65 (talk) 00:44, 5 January 2025 (UTC)[reply]

Something else I forgot to mention, a NGC 1313-310 has a similar thing with Gaia DR3 data suggesting it is a blend of 2 stars. Infa 65 (talk) 00:52, 5 January 2025 (UTC)[reply]

If you are sure that this is the case, feel free to remove. 21 Andromedae (talk) 21:38, 5 January 2025 (UTC)[reply]

@21.Andromedae Done Infa 65 (talk) 00:02, 6 January 2025 (UTC)[reply]

V Cygni

According to this article https://arxiv.org/pdf/astro-ph/0601366, V Cygni has a temperature of 1,880 K and a luminosity of 25,586 L_☉, using the Stefan-Boltzmann law it would have a size of 1,507.78058 R_☉, should we include this star as the largest star in the Milky Way or not? Orangefanta120 (talk) 07:16, 5 January 2025 (UTC)[reply]

@Orangefanta120 That temperature seems strangely low, although it may be possible since it's a carbon star but I don't really know much about them. It would be interesting to have the largest known star not being an RSG though.... Infa 65 (talk) 12:30, 5 January 2025 (UTC)[reply]

Another star in the same study, V688 Monocerotis was estimated to have a temperature of 1,670 K. Orangefanta120 (talk) 16:13, 5 January 2025 (UTC)[reply]

See this. 21 Andromedae (talk) 21:38, 5 January 2025 (UTC)[reply]

That source contains multiple outdated luminosities and temperatures for stars. The table of largest stars by angular diameter contains this star, and the angular diameter and distance estimates give a radius of ~750 to 850 R_☉. 21 Andromedae (talk) 21:36, 5 January 2025 (UTC)[reply]

Just noticed it was in the list at 770 R_☉. Orangefanta120 (talk) 23:52, 5 January 2025 (UTC)[reply]

The List of largest stars row template has to exit

Surely, it was useful before, but it is now introducing some issues, for example i tried to round some radii of stars using the template, in Visual Editor, but it had some bugs when i edited the template directly, so i would suggest removing the template from this list, but not deleting it given it would broke the edit history. It only has disvantages compared to simply using {{solar radius calculator}} in a normal table, which is a lot more versatile. Also, i also intended to add additional columns such as spectral class, which can't be done due to the template limitation. 21 Andromedae (talk) 01:12, 11 January 2025 (UTC)[reply]

I would rather fix problems in the template rather than scrap it simply because you encountered difficulty. However, you have been incredibly vague, and thus I cannot assist. I would also note you haven't even edited this page in almost two weeks. Primefac (talk) 14:24, 11 January 2025 (UTC)[reply]