Talk:NGC 7419
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363 solar radii seems too low[edit]
363 solar radii seems inconsistently and almost laughably low for MY Cep, a star that has been estimated to be over 100,000 solar luminosities by most sources. The ref that says 363 solar radii says MY Cep is 3,025 K and 10,000 times the luminosity of the sun (which calculates to about 363 solar radii). That looks more like the properties of an AGB star rather than a red supergiant and while MY Cep is said to be the brightest of the 5 bright red stars in the cluster, the 5 bright red stars are obviously stated to be red supergiants by many sources. Should we change the size back to 1,134?JayKayXD (talk) 03:19, 16 July 2020 (UTC)
- I agree, I myself felt like undoing Lithopsian's edit when he replaced the 1,134 size on the List of largest stars for a meagre 363. It does seem to small. Its like VV Ceph (which has been discussed before). But I suppose it is the most recent estimate, and, VV Cephei has been studied more to it, and has good reason to be kept at 1,000 solar radii, but MY Ceph has hardly been studied, so it might not possess that honour.PNSMurthy (talk) 05:32, 16 July 2020 (UTC)
- It looks like an AGB star (not even an MK standard for M7 supergiants), quacks like an AGB star (variability), the question is whether it actually is an AGB star. The new reference effectively says yes. Previous papers, basically from the last century, assumed no. You need to come up with something better than "I don't like it" before you reject a dramatically more modern reference. Professional astronomer vs Wikipedia editor, I know which one I'd go with. If you think the reference is giving bad data, come up with an objective reason why, and why the old papers are more likely to be right. Fun task for the day, answers on a postcard, prizes at the discretion of me. Lithopsian (talk) 15:33, 16 July 2020 (UTC)
- Apparently the limit for Supergiant of Hypergiant temperatures is 3,000 Kelvin and the luminosity at 500,000 solar luminosity that I read somewhere .
- Exact limits are still debated. They appear to depend on metallicity. Several papers by Massey, Levesque, etc. over the last decade or so have aimed to define the low temperature limit for supergiants. It is difficult to define the effective temperature for the coolest stars as they tend to be surrounded by dust that gives them a distinctly non-black-body SED. AGB stars tend to run cooler than supergiants, possibly below 3,000 K. Lithopsian (talk) 13:44, 26 July 2020 (UTC)
- Nope, that's a little off. Supergiant stars can be cooler than 3,000, though its rare. And the Eddington luminosity limit is 660,000 Lbol. An example of an extremely cool star is S Cassiopeia with a temperature of 1,800 Kelvin, though I don't think its an RSG or red hypergiant.PNSMurthy (talk) 03:37, 24 July 2020 (UTC)
- I've heard 3,400-3,700 K, 300,000 solar luminosity and 1,500 solar radii was the limit for red supergiants.174.88.75.190 (talk) 03:41, 29 July 2020 (UTC)
- Sooo, Stephenson 2-18 is not at the limit for how cool and how luminous a red supergiant or red hypergiant despite its extreme luminosity of 440,000 solar luminosity and its cool temperature of 3,200 kelvin??? THE COLOSSAL GALAXY NAMED IC1101 (talk) 04:03, 25 July 2020 (UTC)
- Yes, I have seen stars cooler than Stephenson 2-18...Oh... It is S Cassiopiae with E, Not S Cassiopeia without the E. --THE COLOSSAL GALAXY NAMED IC1101 (talk) 05:18, 25 July 2020 (UTC)
- Oh... Shall we discuss about RHI84 10-683 ?????? I don’t know if the size is inaccurate or not... The reason I considered it inaccurate is because it is over 2,200 solar radii. During the lifespan of the list, Those sizes above 2,200 solar radii like RMC 87F, WY Geminorium, WOH G17, THA 34-26, and RS Mensae have been removed, leading to me believing the sizes above 2,200 solar radii are most likely inaccurate. It is just for me fishy...THE COLOSSAL GALAXY NAMED IC1101 (talk) 04:32, 26 July 2020 (UTC)
- S Cassiopeiae is Weird.... THE COLOSSAL GALAXY NAMED IC1101 (talk) 04:41, 26 July 2020 (UTC)
- There have been quite a few more stars like that, like Westerlund 1-26 and WOH G64. But, I actually don't know. Whom am I to tell what star's size is accurate or not?PNSMurthy (talk) 05:25, 26 July 2020 (UTC)
- What do you mean???--THE COLOSSAL GALAXY NAMED IC1101 (talk) 05:24, 27 July 2020 (UTC)
- There have been quite a few more stars like that, like Westerlund 1-26 and WOH G64. But, I actually don't know. Whom am I to tell what star's size is accurate or not?PNSMurthy (talk) 05:25, 26 July 2020 (UTC)