Talk:Andromeda Galaxy

"With a mass of about 1.5 times more than the Milky Way". Better write, if that is what is meant: "With a mass of about 1.5 times that of the Milky Way".
S.

I've just done a brief google searching, and quite a lot of sources say that M31 is less massive than the Milky Way. Maybe more research is needed before adding that info. [1] (http://www.eso.org/outreach/eduoff/catchastar/cas-projects/latvia_andromeda_1/salidz.htm)[2] (http://adsabs.harvard.edu/cgi-bin/bib_query?2000MNRAS.316..929E) --Lorenzarius 10:28 Jan 27, 2003 (UTC)

Someone has just edited this page and changed some data regarding the distance of the Andromeda galaxy. Is this vandalism or is it correct? --ChicXulub 21:35 July 20, 2004 (UTC)

There is a good deal of uncertainty in the mass of any galaxy, but the SEDS page linked in the article sites a fairly recent paper that claims the mass of M31 is substantially less than that of our own galaxy. I will probably go through and correct that and a few other issues later once I look at some more sources.

Oh, and the distance change is probably correct. Just so you know for other astronomical objects: a satellite (Hipparchus) went up and information from it has caused astronomers to change the distances for many objects, so if you see a lot of changes in entries it could be because of that.

I just added a Hubble pic of M31, and moved the Obs. data down, so that they wouldn't have right align/float problems. Hope that's ok.  :) --Etacar11 00:36, 12 Jan 2005 (UTC)

Unfortunately, that image is neither from Hubble nor in the public domain. You need to contact the authors (http://www.astrophoto.com/M31new.htm) and ask them about releasing a version under GNU FDL. See Wikipedia:Image_use_policy#Copyright_(images) for more info. I just removed a prior image on this page recently from another source who did not want his image used. It was also incorrectly credited to NASA. Please be careful to check the source!

As an aside, Hubble would need a huge mosaic of exposures to cover the large (relatively speaking) area of the sky that M31 covers. I don't believe this has been done. There are some shots of globular clusters and the nucleus of M31 from Hubble, however. --mh 02:58, Jan 14, 2005 (UTC)

Hmmm, you're right, guess I got confused by it being on the Hubble website. The size part slipped by me. Sorry! --Etacar11 04:04, 14 Jan 2005 (UTC)

I found another M31 image here: NOAO (http://www.noao.edu/image_gallery/html/im0424.html), and I think its ok to use by NOAO conditions of use. Any objection? --Etacar11 01:10, 15 Jan 2005 (UTC)

I wouldn't personally have any, but the conditional use clauses (http://www.noao.edu/image_gallery/copyright.html) aren't completely compatible with GNU FDL since they don't grant unrestricted permission through use and reuse (e.g. commercial use requires special permission). They are not public domain, unfortunately. --mh 20:52, Feb 1, 2005 (UTC)

Yeah, I didn't upload it. But someone did put a nice GALEX pic in the article, though. --Etacar11 21:50, 1 Feb 2005 (UTC)

Update

While updating the infobox style, I had to make a few choices I wasn't sure about, so I'll note them here.

• It seems absurd to be giving two significant digits to measurements where we aren't even sure about the first digit. (That's a feature of the infobox template, not the page before my editing.) Is the "3-4 × 10¹¹" style too ugly? If so, what can we use in its place, to indicate that there's that much uncertainty? "3 × 10¹¹ — 4 × 10¹¹"?? That's ugly and long.
• I wanted to go with some estimates of its mass and radius, rather than leave them "unknown", so I used some of the values from the linked SEDS page. I chose to go with the mass of the galaxy itself, excluding its halo (& presumed dark matter); if there's a standard for using the halo mass for these, the mass should be 2.45 ×10⁴², 1.23 ×10¹² (and don't ask me how many significant digits that actually deserves!).
• I have no idea what the colour scale is when referring to a galaxy rather than a star. Somebody go find out. ;) Meanwhile, I leave it "unknown".
• Absolute magnitude should be easy enough to figure out, and if no one else finds a value really quickly, I'll put one in. But it seems kind of meaningless for this kind of thing, anyway, I would think. But again, that's a critique of the infobox template.

--John Owens (talk) 00:29, 2005 Mar 23 (UTC)

John, the visible image you added near the bottom is copyrighted, and I don't think the author has given rights for it to be used under the GNU FDL. You should probably remove it. I notice the image itself is slated for deletion soon anyway. --mh 21:27, May 5, 2005 (UTC)

Andromeda Galaxy THREE times bigger than the Milky Way??

News Flash!(May 30)

http://www.reuters.com/newsArticle.jhtml?type=scienceNews&storyID=8643726

This is already accounted for in the article. Nandesuka 19:39, 4 Jun 2005 (UTC)