Talk:UGC 2885

416,000 or 832,000?

I've just created this article days ago. Before I've created this article I searched this topic on Google. First pages show you that UGC 2885 is more than 800 kilolight-years in diameter. But I searched to 20 pages and now they gave values of 416 kilolight-years.

Now for it to make sense to the two, I've assumed that the figure of 416,000 light-years was the radius, giving you 832,000 light-years, approval to the first one. But still I think this is not the case. Feel free and edit my article if you have a reliable source that gives its size. Thank you! Johndric Valdez (talk) 13:20, 11 September 2013 (UTC)

I saw a source that says UGC 2885 is over 800,000 ly. in addition, it contains papers. So yes, this source could be reliable. ZaperaWiki44^{(✉/Contribs)} 13:04, 22 May 2018 (UTC)

@ZaperaWiki44: I read the three papers (well one is a book) presented at the site of the claim of the 250kpc diametre. In the book is written that the "Its rotation period is nearly 2 billion years at a distance of 125,000 parsecs from the nucleus" [1]. It looks like the claim is based on this paper [2], where the distance of 118 Mpc is adopted, which is however not used from more recent papers. It used the now defunct Hubble constant value of 50 km/s/Mpc (now the accepted value is more or less 70) to deliver that distance. The other two papers used adopt the distance of 56.8 Mpc [3][4].

From NED the distance based on redshift alone is 77.4 Mpc (250 Mly). The distance delivered by the Tully-Fisher method is 71.1 Mpc [5]. At this distance the diametre of UGC 2885 along the major axis is 113.75 kpc (=370 kly) (NED). Because this measurement is based on more recent data, it is also more accurate.

More recent papers adopt similar sizes. Saburova (2018) adopts optical radius of 41.53 kpc (83.06 kpc diametre) [6], Schulz (2017) adopts radius 33.89 kpc (67.78 kpc diametre) [7]. Hunter et al. (2013) delivered a radius of 72 kpc for the most outling HII regions [8].

So the value of 122 Mpc radius is based on a 40 year old paper which used defunct methods to calculated the distance, overestimating the size of UGC 2885. --C messier (talk) 10:51, 16 December 2018 (UTC)

@C messier: Ok! I will change the radius of UGC 2885. After all, that value/radius of over 122 kpc (over 400 kly) looks highly obsolete. So I can be agree with you. Thank you for telling me. ZaperaWiki44^{(✉/Contribs)} 12:50, 8 March 2019 (UTC)