Talk:Stephenson 2 DFK 1/Archive 1

This is an archive of past discussions about Stephenson 2 DFK 1. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Archive 1

St2-18 is 2,150 Rsol

The 2,158 solar radii comes from a rounded up luminosity (440,000 Lsol). The real luminosity is about 436,516 Lsol and calculating using that gives 2,150 solar radii. Nussun05 (talk) 15:57, 14 June 2020 (UTC)

I think the Stefan-Boltzmann law is used wrongly - Using the formula on this page, I make it around 660 times the radius of the Sun 82.45.146.68 (talk) 15:04, 16 June 2022 (UTC)

I don’t know about the formula on the page, But maybe you might have picked a different formula. Please elaborate on this.—The Space Enthusiast (talk) 01:48, 17 June 2022 (UTC)

The 90,000 solar luminosity is too low

The 90,000 solar luminosity appears too low for a star so bright at 6 kiloparsec or 20,000 light years.User 122.2.30.162

And? Lithopsian (talk) 12:07, 2 July 2020 (UTC)

Just that. User 122.2.30.162 — Preceding unsigned comment added by 122.2.30.162 (talk) 13:18, 2 July 2020 (UTC)

Not for us to say. That paper used a distance of 5.5 kpc. Bright is relative, it is almost invisible at optical wavelengths, and it isn't even the brightest star in the cluster at some infrared wavelengths. I'd love to see your calculations on why the luminosity is too low, not that it can go in the article. Lithopsian (talk) 14:05, 2 July 2020 (UTC)

Oops, sorry. — Preceding unsigned comment added by 122.2.30.162 (talk) 14:40, 2 July 2020 (UTC)

I want to talk and create articles of the other stars in Stephenson 2 like Stephenson 2-DFK-2, Stephenson DFK-3 and more. --122.2.30.162 (talk) 08:24, 6 July 2020 (UTC)

That's ... not how the stars are named, and, if a star isn't notable, it doesn't deserve an article. PNSMurthy (talk) 02:09, 7 July 2020 (UTC)

Anyone can edit any Wikipedia article (excepting some that have been consistently vandalised), but to create new articles it is best to make yourself an account and then go to WP:AFC. People there will lead you through the creation process. Actual page creation is very easy, but creating one which is notable and reliably-sourced is important or it is likely to be immediately deleted. Perhaps start with some simple edits at articles that you have an interest in, like Stephenson 2? Lithopsian (talk) 14:08, 7 July 2020 (UTC)

UY Scuti vs Stephenson 2-18

Can somebody add a picture that includes UY Scuti and Stephenson 2-18 in size comparison? Also, R.I.P UY Scuti's spot for the largest star. — Preceding unsigned comment added by StaleGuy22 (talk • contribs) 13:47, 7 July 2020 (UTC)

Hi, I am THE COLOSSAL GALAXY NAMED IC1101. I am 122.2.30.162, and I created a sandbox. --THE COLOSSAL GALAXY NAMED IC1101 (talk) 06:04, 8 July 2020 (UTC)

Yep, UY Scuti is no longer the largest star. Stephenson 2-18 is around 2.84 times the size of UY Scuti.

Mass

What is the Mass of Stephenson 2-18? I am sure it is 25 -40 solar masses. --THE COLOSSAL GALAXY NAMED IC1101 (talk) 08:28, 16 July 2020 (UTC)

Probably is, but you'll need a reference if you want to put it in the article. Lithopsian (talk) 16:20, 16 July 2020 (UTC)

Mass? You never know. Supergiant mass does not always correspond directly to supergiant size. For example, XX Persei is quite massive, and is only 700 solar radii (Messineo and Brown gave 500).PNSMurthy (talk) 01:06, 18 July 2020 (UTC)

Would it make sense to mention in the article that information on its mass is unknown or lacking? Samuel.progin (talk) 11:21, 28 October 2022 (UTC)

Yes there really should be a mass reference here. Fig (talk) 18:42, 2 February 2023 (UTC)

Shall we Put a note that says that The 90,000 solar luminosity will not lead to a Lower radius value so people won't get confused so they won't falsely claim that it will lead to a lower radius value ?????

I think we shall add a note that The 90,000 solar luminosity estimate won't lead to a lower radius value (which corresponds to 978 solar radii) so people won't falsely say it will lead to a lower radius value because when Anton Petrov made his video about Stephenson 2-18, He said that Stephenson 2-18 has a Huge uncertainty when in actuality, The lower estimate (474 solar radii) was referring to another star! Now some people say its 474 solar radii. Shall we put a note that says that Stephenson 2-18 is not 978 solar radii so people won't falsely claim that it is 978 solar radii ??? --THE COLOSSAL GALAXY NAMED IC1101 (talk) 06:07, 18 July 2020 (UTC)

Oh, yes, I know that youtube influencer (though I guess they're called 'youtubers'). I do remember a comment telling him to re-make the video because of that inaccurate stat (was that you?). I do think you could put that, but I don't think its needed, because, the general public, at least I think, will not know the equations used to find solar radius (as Lithopsian rightly stated), so will simply use the value we stated.PNSMurthy (talk) 06:33, 18 July 2020 (UTC)

It was me. Maybe Some people know how to find the radius, Including the Joey P.Fiasco. Let's add it just in case. --THE COLOSSAL GALAXY NAMED IC1101 (talk) 07:05, 18 July 2020 (UTC)

That's rare, and even if such people are there, the last place they would come to is WP, They'll go to come scientific journal. No one uses WP as a citation - though we're here to try and change that and make WP reliable. WP's just for the average lay person who just wants to know a vague description. And as for our friend, the sockpuppet, as you know, he has refrained from (more likely can't because of his previous attempts at sockpuppetry) edit WP.PNSMurthy (talk) 07:17, 18 July 2020 (UTC)

When we start calculating our own radii, we leave ourselves open to people doing the same thing and perhaps reaching less reliable conclusions. I think we should avoid putting in text about what isn't. If people want to go around elsewhere making stuff up, that's their problem. We definitely don't want to be adding data only to say that it is wrong. What we could do is add more explanation about where 90,000 R_☉ came from and perhaps why the newer value could be considered more reliable (assuming we decide it is more reliable). Or more discussion of the distance, which is basically just assumed. Unfortunately, 90,000 L_☉ would inevitably mean a smaller radius, there's no way around it, but we can't really say what it is, or even what it isn't. Lithopsian (talk) 14:31, 19 July 2020 (UTC)

Lithopsian, What do you mean? does it still mean 2 Luminosities but One Radius? Also, Is HV 888 Not the Largest as claimed on Sam Halls' post? Another,What do you mean by "Unfortunately"???--THE COLOSSAL GALAXY NAMED IC1101 (talk) 07:00, 20 July 2020 (UTC)

I mean quote reliable sources. Don't make up things that aren't in the reliable sources, and don't pick wehat you want to be instead of what actually is (in reliable sources). Reliable sources of a similar age give two very different luminosities and so both are in the starbox. Only one of them gives a radius, so only one radius is in the starbox. Do you think any of that should change? Do you think we should explain it differently in the text, where we have a little more flexibility? Lithopsian (talk) 10:20, 20 July 2020 (UTC)

So, The Fact that Stephenson 2-18 is only 978 solar radii is not true? --THE COLOSSAL GALAXY NAMED IC1101 (talk) 14:00, 20 July 2020 (UTC)

The question is meaningless. We don't know these values with anything like enough accuracy to call them "true facts". There is only the best observations and calculations that different reliable sources have published. And 978 R_☉ isn't one of them. We can imagine in our heads what the radius might be if the luminosity was 90,000 L_☉ and assuming some temperature, but that is nowhere near good enough to write in Wikipedia. I assume 978 R_☉ is calculated assuming a temperature of 3,200 K, but we have no reason to think that is the right temperature. The calculation of 90,000 L_☉ implicitly assumes a certain temperature, but we don't know what it is. Most likely it is higher than 3,200 K and the radius would be even smaller, but we just don't know without doing some non-trivial calculations. Lithopsian (talk) 14:36, 20 July 2020 (UTC)

Ok. So, in conclusion, Stepehnson 2-18 is just 2,150 (or 2,163 is you use 5,778 Kelvin) solar radii? — Preceding unsigned comment added by THE COLOSSAL GALAXY NAMED IC1101 (talk • contribs) 15:21, 20 July 2020 (UTC)

Indeed, unless their is another estimate (which, judging by St2-18's new title and popularity will come eventually), that contradicts this one and gives different parameters.PNSMurthy (talk) 03:11, 21 July 2020 (UTC)

Is it also safe enough to declare it is one of the largest or even THE Largest star known ? --THE COLOSSAL GALAXY NAMED IC1101 (talk) 12:15, 21 July 2020 (UTC)

Naming

Since Stephenson 2 DFK 1 is the original name of the star, and since it was assigned before the current name (St2-18), shouldn't it be used as the title, instead of the article's current name?PNSMurthy (talk) 06:30, 21 July 2020 (UTC)

Um.............. I choose To let It remain. People might once again get confused about the Name, and I want to prevent that. --THE COLOSSAL GALAXY NAMED IC1101 (talk) 07:36, 21 July 2020 (UTC)

The original name isn't always the one in most common use. Just for reference Stephenson 2 DFK 1 is not the original name. The original "name" was just "1", an entry in a table. DFK refers to the initials of the authors of that paper and was used in a later paper to distinguish between "1" and "18" which had been used in another paper. Simbad uses the designation Cl* Stephenson 2 DFK 1 because it is unique, but nobody has ever actually used that name. It also uses [DNZ2010] St2-18, referring to the 2010 paper which gave the star the number 18. It never calls it Stephenson 2-18. Stephenson 2-18 is also not used in scientific literature, it has essentially been created by Wikipedia. Negueruela et al (2012) refers to it just as D1. Fok et al. (2012) uses St 2-18. There is such a limited published base that it is hard to infer what the most common usage might be, except for web references to the name Stephenson 2-18, a truth created by Wikipedia. Lithopsian (talk) 14:30, 21 July 2020 (UTC)

Ok. Please reply to My question in the discussion above, My new question is about how it is safe to declare Stephenson 2-18 as one of the Largest stars or even THE Largest star? If you noticed I am asking so many questions about Stephenson 2-18, Is because It is my favorite star and I'd love to know more about it.--THE COLOSSAL GALAXY NAMED IC1101 (talk) 15:15, 21 July 2020 (UTC)

Not safe. We would probably be basing that statement on List of largest stars and Wikipedia is not a reliable source. Even going back to the underlying references, we would be taking a value for the radius of St2-18 from one paper and looking in other papers to see if there were bigger stars. That would be synthesis, not allowed. Perhaps there is a reliable source out there saying it is one of the largest known stars. Of course, just by being a red supergiant it is one of the largest known stars since we only know a few hundred in this galaxy. So anything we say should be either explicitly supported by reliable external sources, or vague enough to be undeniably obvious. We have usually settled for saying a particular star is one of the largest known, which is vague enough that it doesn't really need a reference. Lithopsian (talk) 16:02, 21 July 2020 (UTC)

But is it safe to say it is one of the largest, and is a very large star? THE COLOSSAL GALAXY NAMED IC1101 THE COLOSSAL GALAXY NAMED IC1101 (talk) 16:50, 21 July 2020 (UTC)

How will Stephenson 2-18 die?

I watched a Deep Astronomy video about the hypernova of VY Canis Majoris on Youtube and I thought: If VY Canis Majoris will probably die like that, I wondered: How will Stephenson 2-18, Larger than VY Canis Majoris, Die? THE COLOSSAL GALAXY NAMED IC1101 (talk) 04:49, 22 July 2020 (UTC)

The video was probably not very scientifically accurate. Red supergiants up to a certain mass explode as a type II-P supernova. Above that mass (about 15 M_☉ or a little more), things are less certain. They may evolve to a yellow hypergiant and then a blue supergiant (again) and possibly to a Wolf-Rayet star. At some point along that evolution, they may still explode as a supernova, but not a type II-P. Alternatively, they may collapse in a failed supernova, essentially disappearing into a black hole with little fanfare. No clear examples of this have been observed yet. Quite what causes a hypernova (or a superluminous supernova, which may well be what the video was talking about) is unclear, but undoubtedley more complex than just a very big star. For example, (some) gamma-ray bursts are thought to occur from highly-evolved Wolf-Rayet stars that are rapidly spinning. Lithopsian (talk) 14:38, 22 July 2020 (UTC)

So, How powerful will it be ??? --THE COLOSSAL GALAXY NAMED IC1101 (talk) 15:13, 22 July 2020 (UTC)

Depends, it might go classical shabang with a run of the mill supernova, or it might do what Lithopsian said and either go hypernova or turn into a remanant without a shabang, which is possibly like what PHL 293B just did. We really don’t know, though, the 5 RSGC clusters (RSGC1, 2, 3, 4 and 5), are a good study lab. I am expecting quite a few supernovae in the Scutum constellation soon...PNSMurthy (talk) 07:57, 23 July 2020 (UTC)

Ok..... I have YET ANOTHER Question...... Will It grow slightly more? --THE COLOSSAL GALAXY NAMED IC1101 (talk) 08:00, 23 July 2020 (UTC)

Where is Alicante 8-S4 BTW? --THE COLOSSAL GALAXY NAMED IC1101 (talk) 08:03, 23 July 2020 (UTC)

Alicante 9-S4? Me an Nussun05 figured that out on discord. I used MK magnitude, so I got wrong numbers. For my second estimate, I used the HR Diagram with Log Lbol to work out the radius, whilst Nussun applied bolometric correction using Levesque et all 2005 'Red supergiants, cool, but not as cool as we thought'.PNSMurthy (talk) 09:26, 23 July 2020 (UTC)

Ok, Please reply to my comment About SpaceImplorerExplorer and an IP User that does not like extreme Sizes on #RX Telescopii. — Preceding unsigned comment added by THE COLOSSAL GALAXY NAMED IC1101 (talk • contribs) 10:44, 23 July 2020 (UTC)

What is the largest star that you have found now? THE COLOSSAL GALAXY NAMED IC1101 (talk) 16:39, 24 July 2020 (UTC)

Excluding THA 34-26, WY Geminorium - but that's probably inaccurate and Stephenson 2-18 is still marked the largest.PNSMurthy (talk) 01:09, 25 July 2020 (UTC)

Ok, Im happy now. Stephenson 2-18 is my favorite star. THE COLOSSAL GALAXY NAMED IC1101 (talk) 03:58, 25 July 2020 (UTC)

How about WY Geminorium? THE COLOSSAL GALAXY NAMED IC1101 (talk) 03:58, 25 July 2020 (UTC)

That's literally the star I just spoke off.PNSMurthy (talk) 04:21, 25 July 2020 (UTC)

Apparently we are going to discuss How was the 2,238 solar radii estimate produced and How is it possibly Inaccurate ??? --THE COLOSSAL GALAXY NAMED IC1101 (talk) 04:41, 25 July 2020 (UTC)

There's nothing to discuss. Countless estimates give much lower luminosities, so...PNSMurthy (talk) 05:03, 25 July 2020 (UTC)

Oh.......... --THE COLOSSAL GALAXY NAMED IC1101 (talk) 05:50, 25 July 2020 (UTC)

Yep.PNSMurthy (talk) 08:53, 25 July 2020 (UTC)

Stage in life

I have created a new section, in attempt to summarize the discussions in this talk page. Is it safe, to do this? And add a citation needed tag until a reliable and suitable ref is unearthed? If not, you are free to remove this section :)

PNSMurthy (talk) 03:04, 28 July 2020 (UTC)

Hypergiant

Isn't St2-18 a red hypergiant (because it possesses a luminosity > than 250,000 Lbol)?PNSMurthy (talk) 02:42, 4 August 2020 (UTC)

Which reliable source claims that luminosity above 250,000 L_☉ makes a star a hypergiant? Have you read hypergiant? It includes a definition of what a red hypergiant is, in so much as there even is such a thing (which of course you could change, given suitable reliable sources). Given that there is no spectral type for M class hypergiants, we mostly have to rely on some author calling a star a hypergiant. I'm not aware of anyone doing this for Stephenson 2-18. As much as anything, its properties are so uncertain that not many people will say anything very concrete about it. It isn't even 100% a member of the cluster, see the DFK paper for details. Lithopsian (talk) 18:39, 4 August 2020 (UTC)

Okay.PNSMurthy (talk) 23:06, 4 August 2020 (UTC)

90,000 Lsol

I've tried like 5 different times to find the luminosity of 90,000 Lsol in the given ref for it, and I've never been able to find it. Can someone please show exactly where in the paper and/or how that luminosity was possibly calculated? Nussun05 (talk) 06:41, 4 August 2020 (UTC)

Page 12 in my version. In the body of the text, not a table, in exponential form, and not easy to spot across a page break. Lithopsian (talk) 18:35, 4 August 2020 (UTC)

Ah, I see that, okay thanks. Nussun05 (talk) 19:09, 4 August 2020 (UTC)

Humphrys et al.

The ref clearly mentions Stephenson 2-18 as RSGC2-18. Why it has been reverted? 2A01:E0A:47A:F100:98E3:5D71:E982:FA0A (talk) 15:00, 7 August 2020 (UTC)

It is a different star. Not every star numbered 18 is this one. The star is clearly cross-referenced as being star #7 from Stephenson's original paper, as well as circumstantial evidence such as the references to Davies et al. (2007), the high numbers used for some stars, #1 (this star) being missing from the analysis, the spectral type of M4, and the modest physical properties matching star DFK 18. Lithopsian (talk) 20:16, 7 August 2020 (UTC)

Also, the star mentioned to be RSGC1-01 (actually RSGC2-01) was said to be the brightest star in the K Band in that region. Only Stephenson 2-18 could fit that description. The Space Enthusiast (talk) 10:05, 23 April 2022 (UTC)

magnitude

So, what is the star's apparent magnitude? The infobox has four figures, all with some letter in parentheses (G, J, H or K).
The article gives Scutum as the constellation, but it is missing from List of stars in Scutum. 109.240.131.161 (talk) 04:50, 8 September 2021 (UTC)

Those are the apparent magnitudes at four different wavelengths, G for the Gaia passband (wide visual/red filter) and three infra-red wavelengths. The whole cluster is essentially invisible in the V passband due to interstellar extinction. Lithopsian (talk) 11:38, 8 September 2021 (UTC)

Removing radius

Due to the great uncertainty (because it greatly exceeds the Humphreys-Davidson limit and the uncertainty in the distance is higher than than 50%), I would say that the radius should be removed because it is very likely an overestimation in the luminosity because of the uncertainty in the distance. So I wonder why it has not been deleted yet? SpaceImplorerExplorerImplorer (talk) 18:16, 12 December 2021 (UTC)

Including the radius is quite misleading and probably leads to people erroneously using the value in their projects. Though I don't see much point in removing it either, I just hope people will read and understand the note. nussun (talk) 21:15, 16 December 2021 (UTC)

Due to the fact that people will probably not scroll down and will probably not read the section it will probably have to be removed or at least the part of the bit in the 'Physical properties' section where it says its really 'extreme' could be removed. SpaceImplorerExplorerImplorer (talk) 17:19, 18 December 2021 (UTC)

We already have a caveat for Stephenson 2-18, and that is at the beginning. It says that while there is a possibility that it is an RSG or even RHG (!), it cannot be ruled out that it is a foreground object. In my opinion, there definitely needs to be more studies about these huge stars, with some focus on this, VY CMA, NML Cygni and others. In fact, I might go ahead and add a similar note to UY Scuti, with the distance being really obsolete (from the 1970's!) and uncertain. Unfortunately, as others have said, those old values are the only ones we can stick to for now, so don't try to be cocky and claim that it is the largest star again.(Note, I am referring to the other people interested in astronomy, not us. We know that the question "What is the largest star" is somewhat moot because we don't know about the other stars in the oodles of other galaxies !)--The Space Enthusiast (talk) 03:58, 31 January 2022 (UTC)

Also, some people already have acknowledged that its radius is uncertain. I don't know about the "extreme" part, however. I am not trying to act like a professional astrophysicist, but maybe the word extreme is there because Davies 2007 mentioned that it has such an infrared excess that it is possible that it experienced some type of extreme mass-loosing phase. While Deguchi (2010) says that it is a normal red supergiant, the authors of the paper say that it is enigmatic. Negueruela (2013) and Verheyen (2012) detected maser emission from the star, suggesting that it has the highest mass loss of the stars in Stephenson 2. Its late spectral type suggests very heavy mass loss. Lastly, we have Humphreys (2020) which once again mentions a late spectral type and extreme properties, but with doubtful membership. That's all and respond if you can. The Space Enthusiast (talk) 12:25, 23 April 2022 (UTC)