Talk:Sanduleak -69 202

Why 202a?

Every reference I own refers to this star as SK -69°202 - no "a". I have not seen any reference to finding a second component in the system justifying the "a". Indeed, every article I can find referring to SK -60˚202a is explicitly a reference to this Wikipedia page.

If nobody objects, I'd like to rename this page to Sanduleak -69° 202 . Tarl.Neustaedter (talk) 01:27, 4 October 2011 (UTC)

Done. Article is now named correctly - Sanduleak -69° 202. — Preceding unsigned comment added by Tarlneustaedter (talk • contribs) 04:57, 8 October 2011 (UTC)

Luminosity and Mass

I reverted edits changing luminosity and mass from 20 and 300-400k to 18 and 100k. The new numbers are plausible, but no reference was provided. One reference I could find in a hurry [1] suggests a mass of 20. Anyone have better references? — Preceding unsigned comment added by Tarlneustaedter (talk • contribs) 08:39, 8 April 2012 (UTC)

SK was not (certainly at times of eruption) a LBV

The linked article just says it was a "blue supergiant", which is an entirely different thing. Smith (2007, AJ 133, 1034) discusses whether SK might have underwent a LBV phase some time before the eruption, but it was never observed or classified as such when it still existed. I will comment that out in the article. --200.104.129.131 (talk) 14:59, 26 July 2012 (UTC)

This article should be a Section in the SN1987A Article

This page is very short, and it would be more practical to merge this article with the Article SN1987A. I also believe other Identifiers for the star should be added. I have added the star's GSC Number by myself but there are still more. ∞Beƒ’Ɛdsteř∞ 14:29, 23 April 2013 (UTC) — Preceding unsigned comment added by Bfedward13 (talk • contribs)

I personally would rather not merge this into SN1987A. It seems reasonable to have a placeholder for information specifically about the SN1987A progenitor itself. Tarl.Neustaedter (talk) 17:47, 23 April 2013 (UTC)

I'm not too bothered either way. I feel there is a proliferation of stub articles about stars whose only claim to fame is to exist, and these two are after all the same object at different times, but there is a problem that we have infoboxes for the two objects that are different. I guess this is why we have links. I've added a main article link in the progenitor section in SN 1987A. Lithopsian (talk) 13:34, 24 April 2013 (UTC)

Strange sentence?

This sounds strange: Work is still ongoing to find just how a star can evolve to this state without first exploding as a supernova while a red supergiant or why it would explode before evolving further, — Preceding unsigned comment added by 88.68.222.184 (talk) 08:44, 22 August 2013 (UTC)

It is indeed poorly phrased. It needs re-wording, if nobody else gets to it by tomorrow, I'll do that. Tarl.Neustaedter (talk) 17:53, 22 August 2013 (UTC)

Re-worded. Tarl.Neustaedter (talk) 21:45, 22 August 2013 (UTC)

Yes, but it no longer mentions the important point that stars in this (assumed) mass range were expected to explode as red supergiants before they even became a blue supergiant. Only then does it become relevant how the blue supergiant itself explodes. Lithopsian (talk) 21:49, 22 August 2013 (UTC)

You have a cite for it? I'll include it, but I couldn't find anything specific on that point. In particular, if it was an LBV, it probably never was a red giant. Tarl.Neustaedter (talk) 22:11, 22 August 2013 (UTC)

Apart from being fairly common knowledge, both the Luminous blue variable article and the Wolf-Rayet star article describe the evolution beyond red supergiants and include references. The supernova article alludes to this post-red supergiant phase and includes yet another references, although it doesn't explicitly state that some LBVs are post-red supergiants. It may also be too strong to explicitly state it as fact since we haven't observed it and can't fully model it, but it is an integral part of the best theories we have. I also looked in the stellar evolution article, but its description of massive star evolution wouldn't be out of place in a 1950's grade school textbook. Might have to work on that ... Lithopsian (talk) 14:59, 23 August 2013 (UTC)

Reworded some more. Any better? Tarl.Neustaedter (talk) 01:12, 24 August 2013 (UTC)

Depending how well its distance from Earth was known...

Assuming it was exactly 168,000 light years away, the year its supernova took place was 166,013 BC.

1987-168,000=-166,013-->166,013 BC.

We should only mention this in the Article, however, if the distance is fairly precisely known. The Mysterious El Willstro (talk) 03:56, 25 August 2014 (UTC)

It isn't that precisely known. We know it was located inside the tarantula nebula in the Large Magellanic Cloud, which gives us a better idea than usual for that distance because we can average what we know about a lot of stars around it. But precise distances aren't known. Besides, the exact year the explosion took place is rather meaningless, given our single point of view - the only relevant date is the one where the wavefront intersected with Earth, 1987. Tarl.Neustaedter (talk) 05:08, 25 August 2014 (UTC)

We should avoid making this sort of statement ... ever ... because it is meaningless and misleading to make this sort of statement about when an event occurred, and the details of relativistic simultaneity are beyond explaining clearly in a quick sentence. Short answer is what Tarlneustaedter said: the only time that matters is when the event is observed (currently at or near Earth). Lithopsian (talk) 13:48, 25 August 2014 (UTC)