Talk:S Doradus

Picture?!

Surely the brightest star in the LMC has a non-copyrighted picture somewhere, doesn't it? This article ought to start with that picture. Jmacwiki (talk) 05:14, 9 February 2009 (UTC)

You're welcome to find one and use it. Be bold.  Xihr  10:43, 9 February 2009 (UTC)

Alas, I have no idea how to insert one. And I couldn't find one with a short search. But fortunately, WP has a lot more contributors than just me. Jmacwiki (talk) 07:00, 10 February 2009 (UTC)

There are help articles on Wikipedia to help you figure these things out. For instance, here's one on adding images. It covers both uploading them and inserting them in an article, as well as other important aspects. In the case of an article like this, you'll want to find the line "| image = " near the top of the page code, and insert the image tag there, so that it shows up in the infobox like you've probably seen on other pages. Notice that there was already a tag for an image there, commented out, so it'd give you an idea how it's done, as well as the importance of establishing that such an image is available for legal use on Wikipedia. But as Xihr said, Be bold. If you find something that would improve Wikipedia, by all means do it. It's not going to improve itself on its own, you know. Nottheking (talk) 10:50, 21 May 2009 (UTC)

Spectral Class vs. Surface Temperature

Are there any other sources on S Doradus' spectal type? I'm not entirely sure if the current source is a viable one, as it's another encyclopedia that does not appear to cite its sources. Compared to the source given by the Lamers paper, with an effective surface temperature of 9000-20000K, that would give it a spectral type anywhere from B5 to A4. Nottheking (talk) 11:00, 21 May 2009 (UTC)

S Doradus or LBV spectra are variable and it typically doesn't make sense to assign them a more traditional spectral type, although a particular spectral type or temperature could be observed at a particular moment in time. In any case the spectra are generally peculiar with emission lines at "minimum" (high temperature) that are partly hidden at "maximum", often showing as a P Cygni profile. Lithopsian (talk) 19:11, 14 February 2013 (UTC)

R136a1 more luminous ?

The star a1 in the LMC R136 cluster seems to be significantly brighter than S Doradus. See the list of most luminous stars. Someone needs to check (& I am called to dinner....) Wwheaton (talk) 02:49, 25 July 2010 (UTC)

Spectral class = LBV?

I see your point that "LBV" is not a classical spectral classification code. However, by definition Luminous Blue Variables have a variable spectral class, a very specific kind of variability including changes in temperature, emission and absorption, and line profile. In the case of S Doradus, this is approximately from F5 to A0, but with so many peculiarity codes it makes your head spin. None of these fully represent the unique spectrum of an LBV star and its variability. Hence: LBV. Discuss :) Lithopsian (talk) 14:13, 6 August 2014 (UTC)

I was the one who made the edit you're referring to (from another computer), and I'm not sure if I entirely agree, although I see your point. While LBVs do vary quite drastically, they also tend to vary between these periods of... well, variability... and quiescent periods where they exhibit a reasonably stable spectrum (relative to the outbursts). Eta Carinae and P Cygni, for example, are both well-established as being B-type hypergiants during their periods of "downtime" - surely there's such a standard for S Dor too? --203.57.209.105 (talk) 13:46, 12 September 2014 (UTC)

You could try to characterise the spectrum of S Doradus at some phase, or at its extremes, but you'd be hard-pressed to find any modern publication that even tries to assign a specific spectral type to the "minimum" phase. The A2-A5 or A0-A5 sometimes seen are hopelessly antiquated values, as it the A5aeq given at Simbad. S. Doradus is hotter than early A when quiescent, but still showing strong metal lines due to the stellar wind and altogether not a normal spectral type, with complex and variable line profiles. You specifically mention P Cygni as a well established B hypergiant (I would disagree, but it hasn't shown LBV variation in modern times, so as good a candidate as any for getting a specific spectral type)), but S Doradus is typically hotter than P Cygni ... so is it still A class? Despite what Wikipedia says (might have to do some edits), eta Car is hardly a well-established B hypergiant. Simbad says F:I_pec_e (sic!), but even when quiescent the spectrum has defied a conventional classification, partly due to the confusing intrusion of lines from the hotter companion, but it also appears to represent a cooler (although more peculiar) star than S Doradus. However Eta Carinae may well never have been observed fully quiescent, or is such an extreme star that it doesn't make a good comparison for anything. In outburst S Doradus shows a late A to early F spectrum, but that is probably from an extremely dense stellar wind (pseudo-photosphere) rather than a conventional stellar surface. I chose to represent all that information with just three letters, but maybe you can do better ;) I doubt anything less than a sentence can do justice to it. 81.103.170.84 (talk) 15:43, 12 September 2014 (UTC)

That was me. Wikipedia logged me out. I've searched recent publications on LBVs in general, looking for how they define the spectral types for the class. They don't, at least not in terms of a particular spectral class. Older works often refer to B supergiants, but that is clearly inadequate since a number are now classified as O or WR when quiescent. I do find individual cases where a spectral type is given for the quiescent state, but that is often historical data. Difficult, but there's always room for a new paradigm. Lithopsian (talk) 15:51, 12 September 2014 (UTC)

In a very new pre-print, I found this description "their spectral types vary between late O/early B and A/F supergiants". Lithopsian (talk) 10:49, 14 September 2014 (UTC)

550 - 1,000 R_☉

@Casliber, the reason why I said that S Doradus is once thought to be 550 - 1,000 R_☉ (currently obsolete) is because of an earlier edition of List of largest stars: https://en.wikipedia.org/w/index.php?title=List_of_largest_stars&oldid=95198043. The 550 R_☉ came from the Stefan-Boltzmann Law and the 1,000 R_☉ from that website that you did not like. It might have been original research, but those values have already left a heavy footprint on the internet, like in this picture: https://upload.wikimedia.org/wikipedia/commons/archive/c/cc/20090217195452%21Star-sizes.jpg . Thank you. ----Joey P. - THE OFFICIAL 22:50, 9 October 2017 (UTC)

That is all well and good...and shows why we need to stick to peer-reviewed publications as much as possible. Cas Liber (talk · contribs) 23:24, 9 October 2017 (UTC)