Talk:S2 (star)

reference for linkage between spectral type and mass

i believe the original editor who added this comment was referring to a chart such as https://i.pinimg.com/originals/9a/78/90/9a7890a2a0bd8753877d0233e8427b86.jpg while clearly not an authoritative source, this looks correct to me based on my experience.

Old comment

It would be interesting to add bits of info like "at what speed this star moves relative to the Sag A* at the pricenter and apocenter". Must be not-so-small fraction of c. —Preceding unsigned comment added by 62.40.79.66 (talk) 13:44, 11 December 2008 (UTC)

Mass

I added the current mass estimate to the first paragraph, and a details sub-block to the starbox {I copied the template format I found in the wiki entry for XTE J1739-285}. I'll leave it to future editors to fill in the placeholders, as additional details are observed and published. - Braddarb (talk) 20:05, 12 February 2014 (UTC)

A current mass has not been published so far as I know. The published mass is an estimate of the initial mass of the object, ie. when the star first formed. Lithopsian (talk) 16:35, 31 July 2018 (UTC)

Magnitude

Could someone please (if possible) add the apparent and absolute magnitudes of the star? The article would benefit a lot from that. 80.101.212.102 (talk) 17:47, 27 February 2010 (UTC)

I'm not sure magnitudes are well defined in such cases. These stars are visible only in the infrared, thanks to extinction due to intervening gas and dust, and I suspect even their classifications are unknowable due to muddying of any remaining spectral absorption lines by the same gas and dust (though perhaps their time-varying redshifts allow for some progress there). Greg Roelofs (talk) 03:17, 18 November 2012 (UTC)

Agreed. - Braddarb (talk) 20:14, 12 February 2014 (UTC)

Orbital elements

It would be good to update the orbital elements of S2/S0-2, also. The current set dates from 2003 (close to, though not the same as, those published in http://arxiv.org/pdf/astro-ph/0306220v1) and is significantly at odds with the newer, adaptive-optics-based fits published in http://iopscience.iop.org/0004-637X/689/2/1044/fulltext/tb5.html (2008) and http://www.astro.ucla.edu/~ghezgroup/gc/research/1225506s.pdf (2012). I don't know whether other groups have published competing fits in the past couple of years. Greg Roelofs (talk) 03:17, 18 November 2012 (UTC)

Thank you for the links. I'll try to take care of this shortly, as time permits. - Braddarb (talk) 20:38, 12 February 2014 (UTC)

No info on S1

I can't find anything on S1 other than the paper cited for S2. If at least the orbit has been plotted, how come no article has been created as a stub on S1? Cody-7 (talk) 11:03, 11 April 2016 (UTC)

Little is known about S1, other than being a faint infrared object near the galactic centre, one of several hundred currently catalogued. Its orbit is not known and nothing interesting has been written about it, either by the professionals or for public consumption. It received the designation S1 somewhat arbitrarily rather than by virtue of anything special such as being the brightest or closest. Hence not notable enough even for a stub. Lithopsian (talk) 16:33, 31 July 2018 (UTC)

Not the fastest

The article currently states that S2 at its closest approach is the fastest known ballistic object. This is not true. Its neighbor S14 (aka S0-16) has a very elliptical orbit which gives it a longer period but a much closer periastron distance of 44 AU and a top speed of 11,700 km/s. This can be compared to S2's 122 AU and about 7000 km/s. See e.g. [1]. Amaurea (talk) 00:50, 9 December 2016 (UTC)

Redirect needed?

This star is in the news these days, with periastron approaching, and it is being referred to there as "S0-2", so it suggests a redirect from that name is in order (unless "S0-2" is becoming the preferred name, in which case this article should be retitled, and the redirect set to the current name). 173.180.151.52 (talk) 22:40, 22 February 2018 (UTC) anon;

Done (not by me). Lithopsian (talk) 16:34, 31 July 2018 (UTC)

Radio Source Sagittarius A*

I was looking at the first paragraph and Wikipedia in general, why is Sagittarius A* always referred to as a radio source first and then further into the article Sagittarius A* is described as a potential black hole? Isn't the evidence at this point overwhelming that it is indeed a black hole? Is this just a case of Wikipedia not being updated yet for the most current information? I've included some good links below that refer to Sagittarius A* as a black hole first a foremost.

https://www.nasa.gov/mission_pages/chandra/multimedia/black-hole-SagittariusA.html https://www.britannica.com/topic/Sagittarius-A-black-hole http://chandra.harvard.edu/photo/2015/sgra/ https://news.nationalgeographic.com/2017/04/black-hole-event-horizon-telescope-pictures-genius-science/ https://arxiv.org/pdf/1707.01937

143.165.48.50 (talk) 16:28, 12 March 2018 (UTC)

I think it's only a case of being accurate, black holes are very much theoretical objects, distant and very hard to observe and study. Even today, the only thing we're sure of at 100% is that Sagittaius A* is a radio source. --2A01:E0A:11C:7E10:50BD:3CD6:7CC8:325 (talk) 19:36, 19 February 2021 (UTC)

Latest results about passing S A* (of 2018-07-26)

There are news about the event: https://www.eso.org/public/news/eso1825/?lang (btw: pls use also "km/h", not only Imperial units) — Preceding unsigned comment added by 217.109.123.82 (talk) 05:58, 27 July 2018 (UTC)

Paper on further proof of general theory of relativity via S2

Paper via Astronomy & Astrophysics and Science News that linked to it. The details in the paper go way over my head so I'm not sure how to place it in this article, but thought I would link it here. --Masem (t) 14:09, 16 April 2020 (UTC)