Talk:List of largest stars

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)

Uncertainties again...

Several months ago, User:SpaceImplorerExplorerImplorer discussed about deleting Stephenson 2-18 from the list. User:PNSMurthy Came along and said that it would be unfair to remove it. Now, SpaceExplorerImplorerExplorer has added notes to Stephenson 2-18 and other stars with the same reference as that star. The uncertainty says that the distance to those stars are 50 % uncertain and this is actually stated in the paper, but for me that could be referring to other stars as the paper does not specify which star has the 50 % uncertainty in distance. I honestly don't entirely know what to do but I support PNSMurthy's decision. What are your opinions? Thank you. The Space Enthusiast (talk) 01:34, 6 June 2021 (UTC)

I personally think Stephenson 2-18 should go but for other reasons, like that it's brighter in the infrared than all of the other stars, thus giving a luminosity above the theoretical limit (logL = 5.5), another thing is that the temperature is way too cool for red supergiants. With these two factors I heavily doubt St 2-18 is that large, it's probably just a foreground AGB star or other less luminous star. Nussun05 (talk) 08:13, 6 June 2021 (UTC)

Okay I saw your removal of it in your sandbox... But I want to know other's opinions as well.The Space Enthusiast (talk) 08:30, 6 June 2021 (UTC)

The uncertainty refers to stars in RSGC1, RSGC2, RSGC2 SW (which incudes St2-18), Per OB1 and Mc8, and is due to the distances being based on radial velocities. The TESS Input Catalog (v8.0) gives a distance of ~3.9kpc, but this also has a high degree of uncertainty. It is also worth noting the 2010 article that gave a luminosity of 90,000 L⊙ based on a distance of 5.5kpc. This is a big difference to the luminosity (437,000 L⊙) reported in the 2012 article. SpaceImplorerExplorerImplorer (talk) 12:03, 6 June 2021 (UTC)

The 90,000 solar luminosity is based on Mid Infrared and Far infrared fluxes; it does not appear to include the near infrared, where most of Stephenson 2-18's energy is. Including that gives the luminosity by Fok and Humphreys et al. The Space Enthusiast (talk) 10:46, 6 June 2021 (UTC)

Oh, by the way, I have talking with Lithopsian and I said that there was a 50% uncertainty in St2-18's distance. He found the uncertainty in Fok.et al and said it was meaningless, because almost every other star in the list has uncertain distances (Especially those in Andromeda). What do you think of this?The Space Enthusiast (talk) 04:00, 7 June 2021 (UTC)

Is there then anything meaningful to say about the sizes of stars with a great uncertainty in their distance, especially those, such as Stephenson 2-18, that have a radius so much higher than what is predicted by theory? You could also argue then that most of the list is meaningless due to the fact that almost all stars have distances measured by radial velocities and that there would be a great uncertainty in the distance. SpaceImplorerExplorerImplorer (talk) 16:59 8 June 2021 (UTC)

The sizes are not meaningless, we should take note of things in the “Caveats” section. The Space Enthusiast (talk) 00:15, 9 June 2021 (UTC)

Yikes, indents would help. Anyway, the list is essentially meaningless and has been for a decade or more. The stars at the top of the list are statistically those with the most incorrect radius values. We have databases of thousands of (possible) red supergiants, identified by algorithm and classified by another algorithm, without much sanity checking. Objects such as foreground stars become classified as enormously luminous red supergiants. Out of true supergiants, of which the largest are of similar sizes within a modest range, the ones with the most inaccurate, for example, distance appear larger than the others and percolate to the top of the list. The star at the top of the list on any given day is almost certainly there because its radius is wildly inaccurate. Lithopsian (talk) 15:01, 10 June 2021 (UTC)

I've floated the idea of just nuking this article before, but no one seems to agree with me. This is odd, since the topic of "this is wildly inaccurate" and "list is essentially meaningless" keeps coming up. Primefac (talk) 15:33, 10 June 2021 (UTC) I've also re-threaded things for readability, especially since two of the usernames are very similar.

I don't think we should delete the page, but it needs a massive rework, and it needs to happen pretty soon. I would like you to try to help me on this, would be nice. Nussun05 (talk) 20:46, 10 June 2021 (UTC)

Should we use your version?The Space Enthusiast (talk) 23:11, 10 June 2021 (UTC)

What sort of rework? Keep in mind we just did a big overhaul of the list a year ago to clean it up and attempt to make it more accurate. Primefac (talk) 23:58, 10 June 2021 (UTC)

I really don't know. Maybe Nussun05's version? The Space Enthusiast (talk) 00:52, 11 June 2021 (UTC)

My version is slightly more accurate, but I still think it needs a huge rework Nussun05 (talk) 10:16, 11 June 2021 (UTC)

Okay, where are the more accurate parts?The Space Enthusiast (talk) 11:05, 11 June 2021 (UTC)

So... I just had a thought - why not include the uncertainties? Don't get me wrong, we can still have a table, but instead of giving them in any sort of "largest to smallest", put them alphabetically (or as it is, to keep the editing necessary low). Then, we can have a <timeline>-generated graphic showing their size with the uncertainties included (see H:ET and mw:Extension:EasyTimeline). This way we're not necessarily advocating for any particular size being "the best", can include references that support multiple sizes, and graphically show just how uncertain some of the calculated sizes can encompass. If we were to do this, I would definitely suggest breaking things up by galaxy, as we don't want the image to be too big. (Note also we don't need to use a timeline specifically, but the graphical software on MW is a little lacking, and I'm not sure an actual chart-with-uncertainties like {{Dot chart}} is really possible) Primefac (talk) 20:11, 11 June 2021 (UTC)

I really don’t get what kind of format you are talking about, but from your words, that is going to be an absolutely massive upheaval of the list !The Space Enthusiast (talk) 00:04, 12 June 2021 (UTC)

And "complete overhaul" doesn't give that indication? Primefac (talk) 02:38, 12 June 2021 (UTC)

”Complete overhaul” gives that indication, but it provided no context to what will the list look like. The term is vague, because it also does not provide context to what will change. The radii? The format? But your words provided a preview to how the reworked list looks like.The Space Enthusiast (talk) 03:55, 12 June 2021 (UTC)

I think it is necessary to include the uncertainties so that each star can be judged on its merits. Even though the caveats are there, it is not clear how they apply to specific stars, so there is a risk that the values in the list are seen to be accurate. I agree that a visualisation of the uncertainties would be useful. Also, changing the page title to List of possible largest stars could be a way of introducing some uncertainty from the beginning. SpaceImplorerExplorerImplorer (talk) 07:22 13 June 2021 (UTC)

The caveats apply to most stars in the list. I would like to see the List's new format! The Space Enthusiast (talk) 08:26, 13 June 2021 (UTC)

The caveats may apply to most of the stars, but this only applies in a general sense at the moment. Each star has a different degree of uncertainty in its radius. This should be made clear. SpaceImplorerExplorerImplorer (talk) 10:59 13 June 2021 (UTC)

I wouldn't disagree with including uncertainties, but we risk making the data appear more credible while actually being less reliable. The radii themselves are clearly comparable to eachother even if extremely uncertain and statistically prone to exaggeration due to the nature of always selecting the largest values from datasets, but any uncertainties that we include will not be in any way consistent or comparable. A good chunk of the values in the table are calculated by us from luminosity and temperature values (or in some cases angular diameters and distances), each of which may have their own uncertainties with no obvious way to weight them without falling foul of WP:OR. If we do have a published radius with a published uncertainty then it will almost always only be a partial uncertainty, for example based on the specific observations in that paper but ignoring for example uncertainties in the adopted distance or extinction. Lithopsian (talk) 13:53, 13 June 2021 (UTC)

Okay, but i would love to see the new list.Also,from your statement, are stars that have relatively uncertain distance but no published uncertainty in the physical parameters have only partial uncertainties? what should we do about these partial uncertainties?The Space Enthusiast (talk) 13:24, 13 June 2021 (UTC)

As a first step to this might I suggest replacing the list with my updated list? Nussun05 (talk) 21:43, 15 June 2021 (UTC)

At this point, this list is becoming too large to manoeuvre and many stars have wildly different estimates stemming from various scientific articles. Its also incredibly unfair to use just one size for each of these stars, since most have many other estimates. Its honestly pointless to try and correct all these stars. Why not just limit our search to well known stars with at least 3 accurate measurements (and state all these measurements in the article)?

Or, instead of stating the radii we derive ourselves from luminosity, etc, why dont we simply state the parameters in the article instead of stating only the size. We're essentially 'making' the sizes ourselves using derived information. I'd suggest stating the base information instead of the sizes.PNSMurthy (talk) 04:43, 22 June 2021 (UTC)