by Ann » Wed Apr 27, 2016 11:38 pm
geckzilla wrote:So I poked around a bit more with the GALEX data because it's fun and I wondered if my eyes were deceiving me or if it was perhaps some kind of quirk of the detector, but I noticed this faintly visible connection between NGC 6872 and its neighboring elliptical NGC 6876. I looked for any other study by other observatories and there was a notable connection between the two
seen by astronomers using data from XMM-Newton. So it's not far-fetched to suppose that this faint connection is also observed by GALEX. Here's a pic.
GALEX_NGC6872-NGC6876.jpg
Fascinating picture, Geck. I love the GALEX images, and I'm really sorry that GALEX is now defunct, and that there is no other telescope photographing galaxies in ultraviolet light. Well, the Hubble does sometimes, but it mostly photographs its targets in far infrared (814 nm) and either yellow-green (555 nm) or orange (616 nm) light. Okay, maybe I got those figures a few nanometers wrong, but basically Hubble doesn't photograph most of its targets in ultraviolet light.
NGC 6872 looks so striking in the GALEX image you posted, and so different from the other galaxies in the group. Even so I must insist that NGC 6872 is a moderately red spiral galaxy, which is obvious from its large bulge and yellowish bright inner arms. I checked the B-V index of NGC 6876, the large elliptical neighbor of NGC 6872, and NGC 6876 isn't that much redder than elongated NGC 6872: its B-V is 1.03 versus 0.92 for NGC 6872. That is not a negligible difference, but it isn't huge. And yet, in ultraviolet light they look so totally different.
NGC 6872 is clearly "fluffy" with its extremely long outstretched arms. It is perhaps not surprising that there should be a bridge of material between (in particular) the fluffiest arm of NGC 6872 and the (likely very massive) elliptical galaxy NGC 6876. But if it isn't surprising, it is sure fascinating to see it.
Thanks for finding and posting that image, Geck!
Ann
[quote="geckzilla"]So I poked around a bit more with the GALEX data because it's fun and I wondered if my eyes were deceiving me or if it was perhaps some kind of quirk of the detector, but I noticed this faintly visible connection between NGC 6872 and its neighboring elliptical NGC 6876. I looked for any other study by other observatories and there was a notable connection between the two [url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2005ApJ...630..280M&db_key=AST&nosetcookie=1]seen by astronomers using data from XMM-Newton[/url]. So it's not far-fetched to suppose that this faint connection is also observed by GALEX. Here's a pic.
[attachment=0]GALEX_NGC6872-NGC6876.jpg[/attachment][/quote]
Fascinating picture, Geck. I love the GALEX images, and I'm really sorry that GALEX is now defunct, and that there is no other telescope photographing galaxies in ultraviolet light. Well, the Hubble does sometimes, but it mostly photographs its targets in far infrared (814 nm) and either yellow-green (555 nm) or orange (616 nm) light. Okay, maybe I got those figures a few nanometers wrong, but basically Hubble doesn't photograph most of its targets in ultraviolet light.
NGC 6872 looks so striking in the GALEX image you posted, and so different from the other galaxies in the group. Even so I must insist that NGC 6872 is a moderately red spiral galaxy, which is obvious from its large bulge and yellowish bright inner arms. I checked the B-V index of NGC 6876, the large elliptical neighbor of NGC 6872, and NGC 6876 isn't that much redder than elongated NGC 6872: its B-V is 1.03 versus 0.92 for NGC 6872. That is not a negligible difference, but it isn't huge. And yet, in ultraviolet light they look so totally different.
NGC 6872 is clearly "fluffy" with its extremely long outstretched arms. It is perhaps not surprising that there should be a bridge of material between (in particular) the fluffiest arm of NGC 6872 and the (likely very massive) elliptical galaxy NGC 6876. But if it isn't surprising, it is sure fascinating to see it.
Thanks for finding and posting that image, Geck!
Ann