Talk:R136a1

Dark Matter

Would it so far out of the left field to surmise there maybe concentration of dark matter at the star's core ("stark" matter) to allow it to become so bulky? — Preceding unsigned comment added by 203.77.53.185 (talk) 14:29, 18 July 2011 (UTC)

@203.77.53.185

No.hi (talk)

Volume

Would this also be the largest star by volume (which seems to be closer to what the image shows anyway)? --Sfnhltb (talk) 14:12, 27 July 2010 (UTC)

Apparently not, see VY Canis Majoris. — Martin (MSGJ · talk) 14:43, 27 July 2010 (UTC)

@Sfnhltb

The image doesn't show R136a1 as a large star. It doesn't even look big.

Physical characteristics

Stars between about 8 and 150 solar masses explode at the end of their lives as supernovae, leaving behind neutron stars or black holes. Having established the existence of stars between 150 and 300 solar masses, astronomers suspect that such an enormous star will perish as a hypernova, a stellar explosion with an energy of over 100 supernovae (1046 joules).

wrong, make that 12 to 60, hypernova would be any star exceeding that mass. as to black hole, smallest black hole discovered yet is 3.8 solar masses and it was created either by collision of two neutron stars, or by a very large star exceeding 30 solar masses. Therefore article needs bit of editing...

That sentence was taken out when I rewrote it. hi (talk) 20:06, 10 May 2015 (UTC)

Ultraviolet Star

Its energy temperature (Boltzmann's constant multiplied by its kelvin temperature) is about 4.57 eV, which falls in the near ultraviolet range. So while the star looks blue to the human eye, and is described as blue in the text, it seems like it might be more accurate to refer to it as an ultraviolet star? Stonemason89 (talk) 19:12, 27 July 2010 (UTC)

It is not described as blue in the text, it is described as a blue hypergiant, which means it should be spectral type-O or type-B and luminosity class-0. "blue hypergiant" is a technical term indicating spectral type and luminosity class. 76.66.193.119 (talk) 07:19, 7 August 2010 (UTC)

I suppose it would be a good idea to create a section on the radiation profile of the star (what colour it looks like to the naked eye, the power spectrum of its radiation, etc) 76.66.193.119 (talk) 07:22, 7 August 2010 (UTC)

@Stonemason89@76.66.193.119

Done.hi (talk) 20:06, 10 May 2015 (UTC)

This star is of magnitude 12 and is seen with an amateur telescope.Was it too nebulous?

-Alexrybak (talk) 05:26, 31 May 2011 (UTC)

cleaning up intro

"currently on record" and "holds the record" in the intro were redundant so I removed them. It was also a bit jarring to see language more suited to sports reporting in a science article. Bhny (talk) 01:02, 15 September 2011 (UTC)

Confusing and populist. Astronomical observations are always discussed as of the time they are made, not the time that the light left the star. It can be fun to speculate what may have "happened already" but ultimately pointless and unhelpful. Lithopsian (talk) 23:39, 20 May 2012 (UTC)

Old, old comments, but I see my reply here doesn't make a lot of sense. I was probably replying to the next section. Lithopsian (talk) 15:11, 9 April 2015 (UTC)

Verb tense

Wouldn't it be more accurate to say "As of 165,000 years ago, R136a1 was a blue..."? Chrisrus (talk) 06:08, 20 February 2012 (UTC)

@Chrisrus

No. In astronomy, except for extraordinary situations where viewpoints come into question, you refer to events as they are seen here. That is, SN1987a occurred in 1987, not in pre-history. R136a1 is a blue star. 01:35, 9 April 2015 (UTC)

Large undo of recent edits

I have just made a large undo. This repeats much the same thing done about a week ago. Clearly I didn't explain my reasons well enough then, so here goes:

• invalid gammar (eg. "It was only until 2010 that the star was recognized to be the most massive", meaning not until 2010). Don't correct grammar unless you have a good grasp of the language.
• removing citation-needed tags without citing the questionable content (eg. the Pistol star was estimated to be 15,000,000L_☉ and 150M_☉).
• Much of the Surroundings section was lifted word for word from the linked R136 and Tarantula nebula articles. This article is about the star R136a1.
• Incorrect description of the Eddington luminosity as it relates to massive stars and their formation. There is nothing to prevent stars far exceeding 150 M_☉ (witness R136a1 itself), but the process of their formation is expected to be disrupted before they become that massive.
• Incorrect description of the evolutionary state of WNh stars. They are (most likely) core-hydrogen burners, certainly not core Nitrogen burners.
• Possible confusion of ionising radiation and just "radiation". I assume. At any rate the statements are incorrect. For example one single star in the Trapezium cluster in Orion produces more than 1/50th of the energy produced by R136a1.
• Assumption that luminosity alone causes the high mass loss observed. This is incorrect, and mass loss depends on the opacity of the material in the outer layers of the star, and the surface gravity, with details depending on particular spectral line opacity. Stars much less luminous than R136a1 have higher mass loss rates.
• Incorrect (still, after I gave the correct value in my previous edit) calculation of the relationship between relative radius and relative volume. Volume varies as the *cube* of the radius. Hence statements about the density are also incorrect. If you don't understand it, don't put your own calculations into the article.
• Overly strong statements about the metallicity of R136a1. I have found no references measuring or calculating the metallicity of the star, only an assumption of a possible value for the purposes of modelling. Such a value should be described very carefully, if at all, and certainly not stated as fact.
• Statement that R136a1 will continue to evolve along the W-R sequence is unsupported by the citations given. WNh stars such as R136a1 do not form part of the classical "WR sequence". They are young, even described as "main sequence" in the cited journal on account of still burning hydrogen in their cores. They evolve into supergiants, possibly blue hypergiants or LBVs, before (possibly) returning to the more typical hydrogen-free WR sequence, although the details are highly uncertain.
• Unsupported own research that x-ray output is large compared to visual light because of high temperature. In fact thermal x-rays are insignificant from any Wolf Rayet star. WN stars do produce some soft x-rays, exact origin unknown, but not measurable thermal x-rays. That requires temperatures of the order of a million Kelvin. The cited reference *specifically* describes this issue.

That may be enough for now. Possibly I removed one or two constructive edits and I apologise. I simply couldn't face making all the exact same line-by-line edits that I made a week ago in the hope of preserving an occasional gem. Lithopsian (talk) 16:06, 9 April 2015 (UTC)

@Lithopsian

@SkyFlubbler

I apologise for this. Maybe I was a bit to eager to expand the article so I didn't look into the details. Looking into the article, I find that it is poorly constructed, so perhaps you and me could expand this article and improve the content as you did with these edits to Eta carinae ([1] [2]). We should try to improve this article because this is a chief discovery in astrophysics. UY Scuti is important as R136a1 in astronomy, yet the article is well-written. Perhaps it is a matter of references, (UY Scuti's ref's mentions all of its properties) but we could try to pierce whatever we've got into a good article. We could also get SkyFlubbler into this because he is a good writer. (and when you reply, please leave it at my talk page) I am. furhan. (talk) 19:33, 9 April 2015 (UTC)i am. furhan.

@Lithopsian

The eddington limit section says, " In practice the theoretical Eddington Limit must be modified for high luminosity stars and the empirical Humphreys Davidson Limit is derived" That says that the eddington limit must be modified for high luminosity stars, i.e R136a1.

@Lithopsian

Distance

The distance to the Magellanic Clouds is widely accepted to be 50kpc (49.97kpc as now described in the article), but I'm intrigued by the description just added of a specific distance to R136 of 48.2kpc. The reference given (poorly formatted, no title, just an eprint url) does not seem to contain anything about eclipsing variable distances to R136. Wrong paper? Lithopsian (talk) 13:00, 5 May 2015 (UTC)

Comment

@Lithopsian Just wanted to ask a question here. I find that Eta Carinae, at 5 million L_☉ and 120 M_☉, is around 2.133 times less massive than R136a1, at 256 M_☉ and 7.4 million L_☉. R136a1 is only 2.4 million times more luminous than Eta Carinae, or 1.48 times. So I was just wondering; shouldn't R136a1's luminosity be far more greater than η Car's?. I mean, a 2.13 solar mass star (Vega, as an example) is around 40× more luminous than the sun. If this was the case with R136a1, it would be around 300,000,000 L_☉. So my question is; shouldn't R136a1's luminosity be far more greater? Or does Eta Carinae (and other stars) have a higher rate of core energy generation? If this is the case, than why isn't it for Vega? I know that I am wrong somewhere, but can someone please explain? If this is a case of evolution, than will R136a1 increase in luminosity as it evolves? hi (talk) 22:04, 6 May 2015 (UTC)

Apples and oranges. Mira has almost the same mass as the sun, yet is 10,000 times more luminous. Lithopsian (talk) 22:11, 6 May 2015 (UTC)

It might have something to do with the fact that Eta Carinae is 10 times larger than R136a1. exoplanetaryscience (talk) 22:14, 6 May 2015 (UTC)

Not really. Mira is much bigger than R136a1, but less luminous. The same luminosity can potentially be expressed by stars of different sizes and temperatures, but ultimately that energy comes from fusion inside the star. Lithopsian (talk) 19:54, 8 May 2015 (UTC)

@Lithopsian

So it is due to the fact that Eta Carinae is more evolved than R136a1? hi (talk) 23:00, 6 May 2015 (UTC)

Better phrased, as a different stage of stellar evolution.See the Hertzprung Russell diagram and discussions about how stars move on that diagram in time. At different stages in a star's lifetime, it will show drastically different luminosities. There isn't a direct relationship between mass and luminosity, except for stars at similar phases in their lifespans. E.g. Lifespan

Tarl.Neustaedter (talk) 19:05, 8 May 2015 (UTC)

Physical proprieties of R136a1

In a VLT flames survey paper, the authors said,

"In our present work we tried to follow a well-defined method of analysis as described in Sects. 3.2, 3.3 and 3.4. In this section we present comparisons with previous works to get a better pic- ture of the systematic uncertainties that can arise from different analysis methods. A comprehensive study of WR stars in the LMC has recently been published by Hainich et al. (2014), who have analysed 17 stars from our present sample. These authors used a simi- lar grid approach as in our work, based on the Potsdam Wolf- Rayet (PoWR) model atmosphere code (Koesterke et al. 2002; Gräfener et al. 2002; Hamann & Gräfener 2003). An important difference with respect to our work is how the stellar luminosi- ties and interstellar extinction are determined. As described in Sect. 3.4 our results mainly rely on IR Ks-band photometry. The optical flux in B and V is matched simultaneously with the IR by adapting RV and E(B − V) in the extinction law. Hainich et al. keep RV fixed and mainly use the optical to UV flux to de- termine E(B − V) based on the LMC extinction law by Howarth (1983). As discussed in Sect. 3.4 this approach may lead to sub- stantial errors if RV deviates from the adopted value. The anal- ysis of Hainich et al. largely relies on the UV range where the uncertainties in the extinction are very high. Our results rely on the IR where the extinction is almost negligible, however, there is a danger of contamination by circumstellar dust or other IR sources. An illustrative case is VFTS482 (BAT99-99, Mk39). For this star Hainich et al. obtain a luminosity of log(L/L⊙) = 5.9 while our value lies significantly higher (log(L/L⊙) = 6.4). As described above Hainich et al. do indeed substantially underes- timate the IR flux for this object. However, there is possible ev- idence for crowding in HST images of this star (cf. Table B.1). Could the excess IR flux thus be due to other sources? Our SIN- FONI IR data of VFTS 482 suggests that this is not the case as the IR spectrum shows the correct line strength, i.e., it is un- likely that the IR is contaminated by other sources. The same holds for the optical range for which a comparison between HST and UVES spectroscopy shows no sign of contamination. For VFTS 482 we are thus confident that our approach is correct. Furthermore, the different wavelength coverage and larger S/N ratio of the VFTS data can explain discrepancies arising from differences in the line diagnostics. This partly leads to different He-abundances (VFTS 482 and 545) and temperatures (∆T 􏰄 10 000K, e.g. for VFTS 545, 617, 1017, and 1025). Af- ter correcting for clumping, there is also a systematic offset of 0.1 to 0.2 dex in the mass-loss rates noticeable. This difference lies within our error bars and is most likely caused by different assumptions in the model physics and atomic data."

This might imply that the stellar parameters derived by hainich et al. are not as reliable as the ones derived by crowther et al. So maybe we could put the numbers back. 142.177.125.164 (talk) 19:01, 10 May 2015 (UTC)

Crowther says Crowther's figures are more reliable than Hainich's? I don't think that's going to make the front page of many newspapers. Is it better to take accurate IR figures and extrapolate wildly to cover that 98% of the radiation that occurs in the UV, or take less accurate UV measurements and not have to extrapolate so wildly? How long is a piece of string! My personal opinion, probably, don't quote me on this, is that the 2010 Crowther paper might be more "accurate", but it is important to remember that none of these numbers can realistically be considered better than ballpark estimates, considering all the sources of errors outside the small model differences they're arguing about. That isn't really for me to decide, luckily. I simply try to pick the most recent paper that isn't obviously speculative or out in left field and preferably takes note of previous publications. In this case it is the Hainich paper, which has the advantage of providing a self-consistent set of values for all the LMC WR stars, but certainly with some caveats that even Hainich acknowledges. Don't fall into the trap of wanting to use a particular number and looking for reasons why you can. You can always discuss differences between different authors in the text. Even perhaps put a range of values in the starbox although I try to avoid doing that except as a last resort - too confusing, could be mistaken for actual variability, etc. Lithopsian (talk) 20:21, 11 May 2015 (UTC)

@Lithopsian You did the same thing with Pistol star here. Hainich does't say that crowther's figures are more reliable, but he does acknowledge that the perimeters derived are uncertain so maybe crowther's are more reliable.aaaaaaaaaaaaaaaaaaaaaa (talk) 00:33, 28 May 2015 (UTC)

I "did the same thing"? You mean I changed a data value from one you liked (ie. a big number for a star you feel an affinity for) to one that is likely to be the best available in the literature? Normally I would suggest that you use experience and a thorough understanding of the published sources to try and extract the most reliable number (if you must extract only one), but I fear you'd just use that as an excuse to cherry-pick your favourite numbers. That is absolutely *not* the right approach. It doesn't matter that every schoolboy for the last decade has been brought up thinking VY Canis Majoris is the biggest star and R136a1 is the most massive and luminous. If new research gives a different answer, then Wikipedia should change. Then all those schoolboys, now young men full of testosterone and their own sense of omniscience, will come along and try to change the article to match what they thought was god-given fact. C'est la vie, try to rise above.

The VLT-FLAMES census is a good recent source for many of these stars. More than just WR stars in the Tarantula region, but not full coverage of the LMC. If nothing else, it is a valuable cross-reference against Hainich's values. Certainly try to consider both sources when a star is included in both. Perhaps more importantly, read Hainich's comments instead of just blindly yanking out numbers. If he says a value is dubious then perhaps ignore it, for example the BAT99-98 which isn't explicitly considered "wrong" as many of the known binaries are but is certainly described as highly uncertain. Lithopsian (talk) 12:15, 28 May 2015 (UTC)

Worklist

@Lithopsian@Casliber@StringTheory11@Huntster Hi guys, I know from some comments here that this article needs a lot of work. I've been trying to expand it over the past few weeks but can someone maybe help out? Also, this article needs a worklist which I can probably not compose. I know the visibility and future sections could use some work and the size, temperature, mass, and mass loss could use a little expansion (and maybe luminosity, since there are a couple of things that I could add). Now, I just mentioned the basics here but I need someone else to compose a more comprehensive one.aaaaaaaaaaaaaaaaaaaaaa (talk) 19:05, 7 June 2015 (UTC)

GAN

How can I nominate this article for a GAN.aaaaaaaaaaaaaaaaaaaaaa (talk) 22:47, 15 June 2015 (UTC)

GA

@Lithopsian@Huntster@SkyFlubbler@StringTheory11@Casliber Do you think this article is ready to be a GA yet? I've spent a lot of my time improving it and I think it's ready now.--aaaaaaaaaaaaaaaaaaaaaa (talk) 18:42, 16 June 2015 (UTC)

Hmm, let's take a look. I have a few chores to do so might take a day or two. Cas Liber (talk · contribs) 22:39, 16 June 2015 (UTC)

I don't think Wolframalpha is a reliable source, unless you can find something saying otherwise. Cas Liber (talk · contribs) 22:43, 16 June 2015 (UTC)

I would agree, although in general simple unit conversions and calculations that anyone can do don't need a source. As a tip, you can use the {{Convert}} template to do the calculations for you. For example, {{convert|1|J|eV}} will display as "1 joule (6.2×10¹⁸ eV)". StringTheory11 (t • c) 23:05, 17 June 2015 (UTC)

I'll try to discuss in the following statement what needs improvement.

• Intro:Needs a little expansion
• Observations:Could use a little expansion too
  • Discovery:This is okay, but needs some rewording
• Visibility:Needs a little expansion and rewording
  • Distance:Rewording on the "awkward" parts. Also, I spent time discussing the measurement to the Magellanic Clouds but I could also spend time discussing the distance itself
  • Surroundings:Could use a lot of expansion. We could probably format it in Eta Carinae form
• Proprieties:Expansion
  • Binary:Expansion and rewording
  • Classification:Needs a little cutting down and rewording
  • Mass:A lot of expansion I've covered the measurement, but it could use some rewording
  • Mass loss:A lot of expansion. Doesn't needs rewording, since that part will be deleted anyway
  • Luminosity:Rewording, maybe a little messing about with the sections. And maybe this could use some expansion.
  • Temperature:Rewording and expansion. Could also mention the temperature itself as well as the measurement
  • Size:Rewording and expansion. Could also mention the size itself as well as the measurement
  • Rotation:Expansion
• Future:Expansion
  • Evolution:Rewording
  • Supernova:Expansion and rewording
• See also:Fine
• References:Wolfram Alpha is fine when doing simple calculations, but when it come to other things (extinction, e.t.c.) this and this are the best resource. Also, these papers have some things in them that are too scientific to understand (for me) so maybe StringTheory11 and Lithopsian could help me, since they have experience in that field
• Notes
  • The reason why I kept on saying "rewording" is because I am not too good a writer. I essentially built the "foundation" for other people to tweak.
  • I could use a lot of help here from some professionals. As I said in my statement on Lithopsian's talk page in "R136a1 demotion":

"You demoted R136a1 from B class because of "Significant errors and contradictions (I removed the worst and tagged many others), a bit sparsely cited, difficult grammar to read." I can understand that.

• About the sparse citations, that is my fault, so I will try to dig up what I can find. I know a lot of citations that I could have used so I will go and add them.

• I don't really know what some of the errors are. I'm not a particular expert in the subject matter. I'm a 12 year old, and am self educated (in astronomy), so I probably will not be able to spot the errors. However, I will be able to spot the ones that you tagged, so I will try to find the refs on that. Once I am finished, I will tell you.

• I apologize for the plagiarism. I had made a different version on my sandbox, but that was really messed up (bad grammar, incomplete information). Anyway I have corrected that, so it is fine (although the grammar is still pretty bad)

• I probably will not be able to correct the grammar so this is up to you.

• I will comment on the part that you deleted in "evolution" in the sections below.

• • About this, maybe you could put that part back and, instead of deleting it, reword (or just add your own words) it so that it will make itself clear. Also, there is a study which we could use to expand the parts on WNh stars. Also, some of the information in the article contradicts the info in that paper, for example, the fact that it said WNh stars stay on the O sequence for a few thousand years, but the ref said that they turn into WNh stars when at the top of the main sequence. (which is probably after <~2 Myr.)

• • About this, I have a comment to make. R136a1 is presumably 80% of its Eddington limit, so 8.7 million ÷ 8 × 10 = 10,875,000, or its Eddington limit. Now, the 80% of its Eddington limit was derived by Crowther in this publication, so they would be using the value of 265 M_☉ and 8,700,000 L_☉. The current luminosity (using the value derived by hainich) is irrelevant here, but I calculated It to be around 65-70%. (Actually, I got a value of 68% which corresponds to a luminosity of 7,395,000 L_☉. Now, this value should differ from the actual value because; The mass is between 256-265 M_☉ (and some studies claim that it is even as high as 286 M_☉), and the value I got was below 7,400,000 L_☉. Anyway, this value should be close to the actual one.)

Now, at its birth, the star was 320 M_☉ so its Eddington limit would have probably been 13 million L_☉ (I don't know for sure, but did some rough calculations). 55% of 13 million is 7.1 million, which was probably its luminosity then. I'm not saying that we should put these numbers in, but just change the wording. (For example, we could say, "The star was probably over half as luminous as its current luminosity at its birth." etc.)

I've now covered the sections that you deleted so now I will move on to its promotion. As I said in my earlier statement,

"I apologise for this. Maybe I was a bit to eager to expand the article so I didn't look into the details. Looking into the article, I find that it is poorly constructed, so perhaps you and me could expand this article and improve the content as you did with these edits to Eta carinae ([3] [4]). We should try to improve this article because this is a chief discovery in astrophysics. UY Scuti is important as R136a1 in astronomy, yet the article is well-written. Perhaps it is a matter of references, (UY Scuti's ref's mentions all of its properties) but we could try to pierce whatever we've got into a good article."

The "refs that we could pierce together" that we got are mentioned here ([5] and [6]) and here. There is also a paper in prep that might be interesting.

Me and you could try to make this a project and improve it. Please reply to me and share your ideas on this.

I will now log off Wikipedia for the day. I probably should be finished cleaning up R136a1 by the end of the week and will notify you if I finish."

As you can see here there are some stuff that need some work. However, this was way back in May 13, and I have cleaned up a lot of stuff since then. I have especially tried to work on the references and reference every single sentence that is more controversial than "the sky is blue". Anyway, getting back to the subject here, I find that Lithopsian is the most qualified person to proofread, since he used to be an astrophysicist. Casliber is the most qualified one at the prose and formatting and StringTheory11 can work with Lithopsian on the proofreading. Lithopsian's comment to me on my talk page might prove interesting since it summerizes what we have to do most:No original research. Anyway, here is the comment:

"First stop has to be WP:NOR. No Own Research. That means anything more complicated than πr2! No working out what someone might have meant when they wrote about the Eddington Limit in a blog. Data, and anything more controversial than "the sky is blue" needs to be confirmed by a reference (technically it only needs to be "verifiable", but better by far to actually have the verification right there so there are no awkward questions later).

Second stop is which sources are good. A web page, even one written by a renowned astrophysicist, isn't a great source. It isn't peer-reviewed, it could just be idle speculation. If it hasn't been published formally, maybe it is rubbish? If it has been published, then use that as the reference instead. Same applies to blogs, press releases, and astro-porn, half of which is probably copied from Wikipedia anyway.

I may or may not edit R136a1 in the future, but I don't have time to do a good job on it at the moment. Hence is just quickly rook out stuff that is plain wrong. I don't have time to proof-read twenty edits a day. I don't have time to write sections on demand. You have to be responsible for what you write. If you don't understand it, don't write it. Even if you understand it, double-check. All the good ideas in the world count for nothing if you write a handful things that are just flat wrong.

A word of advice on page ratings. I haven't seen an official policy on this, but tend try to avoid rating articles that I have heavily edited, or at least rate them conservatively. Over-rating doesn't help anyone. Almost by definition, you think your own articles are good or you would edit them some more. It takes someone else to see if there are problems.

The UY Sct article is OK, reasonably well written but containing some uncited claims and could certainly be expanded. Note that it is class C, which seems about right. Compare the articles given as examples on the documentation pages for class C and class B, you might be surprised how comprehensive they are. Or think that a class B article should be a potential good article candidate. Anything that would be torn to shreds in a good article review probably isn't class B.

Last stop is WP:NOR :)"

References

image

How do we feel about this image File:A image of a Wolf-Rayet star.jpg? I suspect we know too little to assume a wolf-rayer star looks like this - how do others feel? Cas Liber (talk · contribs) 20:50, 12 July 2015 (UTC)

It is a still from a video from here Lithopsian (talk) 22:01, 12 July 2015 (UTC)

Not getting a lot of comments here, but the wide-ranging discussions elsewhere are relevant. I'm not a fan of this type of image, for its own sake. If it offers something beyond a pretty picture, maybe, but not just as gratuitous wallpaper. It can be tough to get star images that are more interesting than just a dot, but that doesn't mean we should make them up. I'm trawling through the article at the moment making edits, but I'll leave images until the end. I've actually done most sections individually, but the overall structure needs looking at. I'm looking at the last section now, the biggest and probably needs a total rewrite. Lithopsian (talk) 16:34, 15 July 2015 (UTC)

Astronomically near future?

In the lead, R136a1 is described as a supernova candidate in the astronomically near future. Essentially all research suggests that this won't occur for *at least* half a million years or so. There are no realistic prospects for an imminent explosion, so is this statement justified? Lithopsian (talk) 20:26, 17 July 2015 (UTC)

No. It is completely vague and unhelpful. Some figures or date ranges are much more useful. I agree with removal. Cas Liber (talk · contribs) 21:59, 17 July 2015 (UTC)

Surface Gravity Units

Hi. Would it be possible to convert the star's surface gravity from cgs to mks? I don't know how to do it myself, and I think the current units are next to useless for many readers. Either meters per seconds squared or G units would be perfect. Thank you. 91.155.195.65 (talk) 23:02, 17 March 2016 (UTC)

I guess I can offer a couple of comments - the surface gravity was added with this edit, but I can't find the cited fact in the reference. Unless it's a derived quantity (in which case we should not be citing it here), it must have a different citation origin. @User:Lithopsian, can you re-check where you got that value?

It is in the reference, but only in the text, and only as an assumption. The assumption is presumably based on valid reasoning and research, but it still might be better to find a paper which actually "measures" the surface gravity. Lithopsian (talk) 14:08, 18 March 2016 (UTC)

On a separate issue, the problem isn't cgs vs mks. Astronomers in general use cgs for historical reasons, but in this case, what you're given (4.0) isn't specifically cgs, but the base-10 logarithm of the value. So this is actually 10,000 centimeters per second squared (10^4 cm/s^2), which means about 100 m/s^2 in MKS units. That's about 10 earth-gravities, which is about what I'd expect for a blue star. So I hope I've answered your question, and also hope we can clear up where that value came from. Regards, Tarl.Neustaedter (talk) 00:48, 18 March 2016 (UTC)

Yes, log(g) in cgs units is pretty much universal in astronomical research. It doesn't make for a simple comparison to earth gravities, but then it isn't meant to. It is used because it conveniently encapsulates the vast range of stellar surface gravities from near zero to squashing-you-flat in what is typically a single digit number. Un-logging it still leaves it in cgs. Converting that to some other units just leaves a number that is entirely unrecognisable, so as unfortunate as it might be to anyone born in this century I wouldn't be in favour of changing it. Especially not using MKS per-se, which is just as arbitrary as cgs, even if it is slightly more modern. If we aren't going to use the units quoted by 99.9% of published material in the field, then we should use SI units, which is N/kg. Which happens to be equal to m/s^2 :) Possibly the starbox template could automatically provide a comparison against earth or solar surface gravity, which would be far more meaningful than some huge number. It is certainly something that should be addressed at the template page or the astro project page rather than just for a single star. Lithopsian (talk) 14:08, 18 March 2016 (UTC)

Mass

Hi,

Shouldn't the mass of R136a1 in the starbox be listed with an error margin, as given in the paper?I am. furhan. (talk) 14:32, 24 March 2016 (UTC)

Probably should, but you may have trouble implementing the exact structure the paper gives; probably best to use ±60 rather than attempting the +60-50 construct inside the infobox. Keeping in mind that the infobox is for quick at-a-glance information, simpler is better, even if it loses some level of detail. Tarl.Neustaedter (talk) 15:35, 24 March 2016 (UTC)

You can do the layout with the val template, but I'm not sure it is helpful information. Does the average reader have even the vaguest idea what ± means, let alone more complex asymmetric error margins? Do the ones that think they know really know? If I had a nickel for every time someone takes an error margin and converts it to a range! Even then, for those few that actually understand the statistical basis of a margin of error, the quoted margin of error only covers a very narrow set of circumstances. For example, in this case the margin of error is in the model, assuming a set of conditions each of which has its own (unknown) margin of error. The 315 M_☉ number most critically assumes no rotation. Another significantly different value, with its own margins of error, is given assuming a particular rotation rate. There are likely to be other sources of error, although it is difficult to be sure what is or isn't captured in the quoted margin. So is quoting a margin of error adding to people's understanding or simply giving them a false sense of security? Are you going to quote margins of error for all the data? What about when you don't have it, are you encouraging people to think that figure is a hard fact when it may actually be a wild approximation? The existing one (occasionally two) fixed number is certainly simplistic, but you need a degree in statistics to start presenting anything more complex. Lithopsian (talk) 16:18, 24 March 2016 (UTC)

I'm of the mind to keep error margins with any quoted numbers, simply to remind readers that uncertainty exists, and roughly the magnitude of the uncertainty. Ideally, we'd specify any error ranges as being at a common significance, but we're a tertiary source, we don't get to require that. The real problem is that in conventional terminology, specifying an unqualified mass of 135 would suggest that the value is known within ±1, which it certainly isn't. Giving ±60 at least gives the order of magnitude of error - we're pretty sure the mass isn't half or double, but we for sure don't know it to the single digits. As for fixing everything to have error margins, sure - we should do that right after we finish ensuring every statement in Wikipedia has a reliable citation :-) Tarl.Neustaedter (talk) 17:01, 24 March 2016 (UTC)

I can go either way. I've included some error margins for some data for some stars. I do it on parallaxes (which have a separate error margin field anyway) and the such where the margin of error really should reflect the accuracy of the given number. Sometimes on orbital data. Elsewhere I usually don't, because I usually don't have it. For Wikipedia's purposes, it may be more helpful to quote a representative range of estimates from different authors, although that is a whole different minefield. Lithopsian (talk) 17:32, 24 March 2016 (UTC)

Agreed that range from multiple sources would be better, but since at the moment we have a single source, I think error ranges are worthwhile. I've made the change (did't know that the val template could do that, nifty!), take a look on whether it looks acceptable. I added a direct pointer to the reference, even though there was an overall reference for the entire section. Feel free to revert if you think it has more problems than benefit. Regards, Tarl.Neustaedter (talk) 21:30, 24 March 2016 (UTC)

What about the mass listed in the first paragraph? Wouldn't it be better if that also stated something like 256-315Msol or with an error margin, instead of a single number that is stated right now (315Msol)? Or is that also to make it easier to read for the average reader? VictordeHollander (talk) 18:22, 26 March 2016 (UTC)

I don't know if there is a hard-and-fast rule, but usually the lede will contain generalizations and the article will later have specifics with qualifiers (which it does, in section 3.3 "mass"). The infobox, where it's essentially a column of numbers, struck me as a good place to add uncertainties, If someone has time to do a major revision of this, I'd suggest the right answers would be that the infobox should have a range (in this case, probably 265-325, that seems to be the range of the center points of different approaches), the masses specified in the mass section should each have error ranges from their respective articles as they are mentioned. The statement in the lead should probably use the center point of the most commonly accepted mass, without qualification. Any better suggestions? Tarl.Neustaedter (talk) 19:17, 26 March 2016 (UTC)

Generally generalisations are not a good thing and we need to be careful about combining disparate material if it hasn't been done (and analyzed) elsewhere. Does the mass section have all calculations and how they were performed and possible weighting now would be the first question to answer.....the material currently needs some more elaboration in how these processes are done and conclusions, plus it must have margins of error. Cas Liber (talk · contribs) 20:55, 26 March 2016 (UTC)

The latest paper contains three different mass values made with different models or assumptions, one of them from a previous paper. They all have associated margins of error and pretty good explanations of how they were derived, as well as which one is preferred and why. We could use any or all of those numbers in the text. I've referred to two of them in the mass section, plus a value from another recent paper. Using just a single value in the starbox and lead is slightly simplistic, but the 2016 paper does state a single preferred value so it is certainly verifiable. We should be careful not to derive any values not stated in published sources, but could state a range if we make it clear where the different values come from (ie. *not* the upper and lower margins of error!). In the lead I often use an approximation to try and express that this is not a number graven in stone for all time, but then you have to throw in a weasel word or two so not perfect.

An interesting comparison here is the age in the starbox, which I also changed recently to quote the 2016 paper. The lower bound is zero, the "preferred" age derived by a method which the paper itself admits is flawed. The upper bound is derived with a different assumption about rotation. The mass follows automatically from the same calculations and assumptions, 315 M_☉ from the zero age and 280 M_☉ from the higher age. Lithopsian (talk) 11:13, 27 March 2016 (UTC)

We should put them all in and why one is preferred. Part of what wikipedia can do is show science as detective work and not tablets on Mount Sinai set in stone. Could always use the preferred in the lead with a footnote. Cas Liber (talk · contribs) 11:38, 27 March 2016 (UTC)

@Lithopsian: @Casliber: Ok, thanks.

1 300 solar radii? w/ref

I have found sites and other Wikipedia pages (on different languages) that claim R136a1 to be over 1 300 solar radii. --Joey P. - THE OFFICIAL (talk) 21:05, 11 July 2017 (UTC)

Who says that R136a1 is 1,300 solar radii? Gotorn 999999 (talk) 10:58, 12 July 2017 (UTC)

R136(a) was once thought to be a single star with enormous luminosity, and presumably a very large size although I haven't seen any formal calculations. Those thoughts were clearly wrong, and reflecting them in this table would be misleading. Picking unsustainable and meaningless sizes, for example of a supernova at some point, would similarly be misleading and picking a "size" for a supernova imposter explosion that wasn't directly observed would be nearly as bad. I'm struggling to think of a single example where there is a reliable modern calculation of a sustained historical size of a star that might go in this table. Perhaps someone wants to make a list of how badly wrong people were about some astronomical facts 100 years ago? Lithopsian (talk) 13:17, 12 July 2017 (UTC)

I am not trying to say that R136a1 is strictly 1 300 solar radii, because I DO know that R136a1 is only 32.1 solar radii. However, I actually found a ref for it:

Not just "not strictly 1,300", but not 1,300 R_☉ at all. Your ref links to nothing but I know the paper you mean. I can't see anywhere that gives that radius. There is a mention that R136a was once mistaken for a 1,000 M_☉+ star, but the important word there is "mistaken". Feel free to start an article about mistaken beliefs in the past, but this doesn't seem to be the place for them. If you do want to go that route, it is worth noting that the original "discovery" papers for R136a as a super-massive star give a radius of ~90 R_☉, not even close to 1,300. Also, it is often conveniently forgotten that other papers from the same era contradicted those results and claimed (correctly, it turns out) that R136a would be resolved into multiple stars just like the cores of other dense massive clusters. Boring news is easily forgotten. Lithopsian (talk) 12:12, 13 July 2017 (UTC)

Thank you. Here is the full page saying that R136a1 is 1 300 solar radii, with the ref included: https://pt.wikipedia.org/w/index.php?title=RMC_136a1&oldid=39925108 And here is another page with the same value, with a different ref that also says 1 300 solar radii: https://de.wikipedia.org/w/index.php?title=Liste_der_gr%C3%B6%C3%9Ften_Sterne&oldid=145607674 --Joey P. - THE OFFICIAL (talk) 23:12, 26 August 2017 (UTC)

The Portuguese page has read the FOS instrument resolution as the radius of R136a1, that's obvious enough. I have no clue what the German page is doing, the reference makes non sense to me. Note that in both cases you have linked to old versions of the pages which have long since been fixed. Lithopsian (talk) 13:32, 27 August 2017 (UTC)

References

"Heaviest star" listed at Redirects for discussion

An editor has asked for a discussion to address the redirect Heaviest star. Please participate in the redirect discussion if you wish to do so. Steel1943 (talk) 20:38, 20 September 2019 (UTC)

R136a1's old mass value and the attempts to re-add it...

Earlier this month and a few months prior, some people have been trying to re-add R136a1's old mass value here and on the List of most massive stars. I will not be discussing about the validity of the old mass value, nor that of the newer ones. Instead, I will use this as a message to all people either unaware or in denial of (sorry if my wording is harsh) R136a1's new mass values. You may like the old one, that is not a reason to re-add it, because Science has improved since then. I understand why people either like it, get attached to it or get sad about its removal (I had this feeling a couple times during similar situations like when Stephenson 2 DFK 1 got removed from the List of largest known stars before getting re-added, or when UY Scuti had the same treatment), but it just has been superceded by the newer ones which are likely more accurate. I even noticed that, a few months ago, a user named User:Omarseid2011 threatened User:Lithopsian just due to his liking of the old mass value! Dear fellow editors, please stop this, and we must move on. Thanks, and peace out.--The Space Enthusiast (talk) 02:03, 16 March 2023 (UTC)