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Sardinia
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Reged: 11/21/05
Posts: 46
Loc: Elkins, New Hampshire
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Trying to resolve contradictory data on Light Years distances for NGC 7335, Ngc 7337 & NGC 7340. I know the distance measurements for these distant fellows is far from an exact science but wondered what folks out there had for info? 
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 6785
Loc: Beatrice, Nebraska
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Well, these objects are so distant that it is difficult to use many of the "standard candles" (Cepheids, planetary nebulae, etc.), so we have to fall back on Hubble's "Law": v = H0 * D, where v is the radial velocity in kilometers per second, H0 is the Hubble Constant, and D the distance in kiloparsecs.
NGC 7335: radial velocity: 6315 km/s
NGC 7337: radial velocity: 6900 km/s
NGC 7340: radial velocity: 6400 km/s
Assuming Hubble's Law is accurate, using a Hubble constant figure of 71, the distances would be:
NGC 7335: 89 kpc or 290 million light years.
NGC 7337: 97 kpc or 317 million light years.
NGC 7340: 90 kpc or 294 million light years.
These figures are also similar those of the associated members of Stephan's Quintet, so the distance to these objects is probably about the same as those of the quintet (estimated between 210 to 340 million light years). However, the above figures for the Deer Lick group remain only *very* rough estimates rather than accurate figures. Clear skies to you.
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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
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BobinKy
scholastic sledgehammer
Reged: 04/27/07
Posts: 950
Loc: Country road
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Thanks for the distance information on the Deer Lick and Stephan's Quintet galaxy groups. These are very interesting, given the distance and formation. This morning was the first time I have heard of these two groups (I am new to amateur astronomy). After looking up the groups in the atlases and guides in my personal library, I googled and found a nice image on Jim Solomon's Astropics website. If you scroll to the bottom of this web page, there is a link to a wonderful full resolution image showing both groups.
Thanks again.
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Bob
38° Kentucky, USA
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BillFerris
Carpal Tunnel
Reged: 07/17/04
Posts: 2582
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Quote:
Thanks for the distance information on the Deer Lick and Stephan's Quintet galaxy groups. These are very interesting, given the distance and formation. This morning was the first time I have heard of these two groups (I am new to amateur astronomy). After looking up the groups in the atlases and guides in my personal library, I googled and found a nice image on Jim Solomon's Astropics website. If you scroll to the bottom of this web page, there is a link to a wonderful full resolution image showing both groups.
Thanks again.
Hi, the Deer Lick Group is a nickname that's gained some limited use over the last 10 years. These galaxies are widely recognized around the world by the NGC designation of the impressive NGC 7331. The nickname is a reference to Deer Lick Gap (aka Deer Lick Pass) in North Carolina. A group of amateur astronomers chose the nickname to commemorate the location where they enjoyed a great night of observing.
While nicknames for astronomical objects have a rich history (i.e. Whirlpool, Ring, etc.), the Deer Lick Group illustrates how nicknaming an object that is already quite well known by a formal designation (NGC 7331) offers little of value to the object's profile. This nickname doesn't describe the galaxies and the galaxies included aren't even members of the same cluster; NGC 7331 is a foreground object.
Bill in Flag
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Grand Canyon Adventure
Lowering the Threshold
18" Obsession
4.5" Meade 4500
10x50 Swift Audubon
Cosmic Voyage
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jeff heck
sage
Reged: 01/16/06
Posts: 371
Loc: stl,mo.
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I also have heard them referred to as the Fleas,which makes more sense to me. 
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"Don't taze me.bro!"
XT10 Orion classic
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BobinKy
scholastic sledgehammer
Reged: 04/27/07
Posts: 950
Loc: Country road
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Bill--
Thank you for the important history of such an interesting name. To be truthful, I was wondering if the name referred to their formation in the sky. Now, thanks to your post, I have learned that it has to do with the observation location.
Thank you again for jumping in and clearing that up.
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Bob
38° Kentucky, USA
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Sardinia
member
Reged: 11/21/05
Posts: 46
Loc: Elkins, New Hampshire
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In the interest and service of my own OP research request I have found an article on NGC 7331, in a 1998 edition of the 'Chicago Journals, Astrophysical Letters which estimates the distance of NGC 7335 at 110 MPC which converts to 358,778,462 Light Years. It estimates NGC 7331 at about 15 MPC, saying further that little is known of 7335 but it should be studied as a possible AGN.
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 6785
Loc: Beatrice, Nebraska
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Quote:
In the interest and service of my own OP research request I have found an article on NGC 7331, in a 1998 edition of the 'Chicago Journals, Astrophysical Letters which estimates the distance of NGC 7335 at 110 MPC which converts to 358,778,462 Light Years. It estimates NGC 7331 at about 15 MPC, saying further that little is known of 7335 but it should be studied as a possible AGN.
I got a good look at the group tonight, and although they were faint, I could see NGC 7335, and NGC 7340 fairly easily, and just got bare glimpses of NGC 7337 (9.25 inch SCT at 169x). On distance figures, the exact distance figure you get when you use the Hubble "Law" formula will depend on what figure you use for the Hubble Constant. It is somewhere between 50 and 100, although figures now seem to be settling down to between 70 and 80. 110 Mpc is probably better stated to be about 360 million light years. The extra figures are not really significant, as we don't come close to having the precision in the distance measurement for those extra digits to have a lot of meaning (maybe +/- 20% error in the distance at best). Clear skies to you.
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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Edited by David Knisely (09/07/08 02:46 AM)
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