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akarsh
March 20th, 2015, 04:29 AM
Hello,

I just found out that the galaxy NGC 5291 in Centaurus has a collisional ring. A peek at a DSS image indicates that this is of similar brightness (if not brighter) than the bridge in Keenan's system.

Centaurus is too low in the horizon for most of us in the northern hemisphere, but I'm wondering if anyone has managed to grab the collisional ring. If so, with what aperture etc?

Any observing notes (about the companion galaxy's bubble-like feature too) will be appreciated. Thanks!

Regards
Akarsh

Jimi Lowrey
March 21st, 2015, 04:17 AM
Akarsh NGC 5291 is also known as the Seashell galaxy not sure were the name came from. I have viewed it with my old 25" but did not see the tidal tails . I did not look for the ring.

Steve Gottlieb
March 21st, 2015, 11:43 PM
I think I first ran across the Seashell galaxy (the companion to NGC 5291) in the excellent coffee-table book "Exploring The Southern Sky” by Laustsen-Madsen-West. But the nickname "Seashell Galaxy" may come from Longmore et al in the 1979 paper "NGC 5291 - a massive, gas-rich and highly peculiar lenticular in the IC 4329 cluster" (here (http://articles.adsabs.harvard.edu/full/1979MNRAS.188..285L)). Bill Keel repeated the nickname in his Mercury magazine article on "The real astrophysical zoo - Colliding galaxies" (which you sent me).

At -30°, I wouldn't consider it too far south for you, Akarsh! I never looked for the pair while observing in the southern hemisphere, so here are my notes from northern California --

17.5" (3/12/88): NGC 5291 is fairly faint, very small, round, small bright core. Forms a double system with MCG -05-33-005 just 0.6' SSW. MCG -05-33-005 appeared very faint, very small, round, nearly attached to the south end of NGC 5291. The companion is known as the "Seashell Galaxy" due to its unusual "whelk" appearance on photographs. Member of the IC 4329 cluster (AGC 3574).

akarsh
March 26th, 2015, 09:00 AM
Thanks for your inputs Steve, and Jimi. From the POSS plates, it looks like Jimi can see the collisional ring with his telescope, but I might be able to see the bubble-like structure in the smaller galaxy in my scope. (I am given to understand that the "seashell" shape refers to the shape of the companion galaxy, the tihng I referred to as the "bubble", and the "collisional ring" is the faint tidal structure that is vaguely seen in the POSS image.)

I found this randomly while searching -- interestingly, the first author is an acquaintance of mine. He worked a bit on the astronomy software I contribute to.
http://arxiv.org/abs/astro-ph/0703002

I forgot to put this on my list, but I will the next time I try. (It might end up being TSP given the flakiness of weather :-/)

Clear Skies

Regards
Akarsh