|
Rick J
Pooh-Bah
Reged: 03/01/08
Posts: 1087
Loc: Mantrap Lake, MN
|
|
Arp 268/Holmberg II is part of the M81 group and is located about 3 mega parsecs from us, about 10 million light years. It is classed as a Magellan type irregular galaxy. Arp classed it under "Galaxies (not classifiable as S or E); Irregular clumps. That would seem to fit Arp 235 posted earlier as well. Being close and having blue giants up to 19th magnitude I was able to resolve many of its brighter stars and star clusters. Arp's comment: "Resolution of stars: Note linear loop of emission regions." I'm not sure how a loop could be called linear but I'm sure he is referring to that looping feature on the east side (left) of the galaxy. The CGPG catalog notes: "Large post-eruptive blue irregular with compact core and many knots." I'm not sure what is considered the core of this guy. I can't say I see it in any image I looked at.
There are several interesting galaxies in the field. Above and slightly left is the oddly red spiral NPM1G +70.0037. I find no distance estimate. Galaxy Zoo in studying the Sloan Deep Sky Survey images has discovered a new class of spiral galaxies, red spirals. This may be one of those. Spiral arms are usually very blue as this is where new star formation is going on. Without current star formation it was thought the spiral structure would quickly break down. So this class of spirals is a real problem to explain.
Down a and to the left of the red spiral is the double galaxy KUG 0815+709. Apparently that bright spot on the upper arm is a second galaxy. Both it and the red spiral are strong IR emitting galaxies.
Most galaxies in the image are anonymous, including the interesting looking spiral below the double spiral KUG 0815+709 and the narrow edge on spiral seen through Arp 236's east side just above that loop of star forming regions. I'd love to know more about it but couldn't find even a mention of it anyplace.
There is a large star cluster centered just above my image, RX J0819.3+7054. Some of its members are seen along the top center of my image. They are somewhat reddened by their great distance of about 2.7 billion light years. None were listed individually however. Therefore I can't separate which are cluster members and which are just background galaxies. Two other clusters are listed in this region to add to the confusion of who belongs to what.
An excellent image of this galaxy taken by the 10 meter Keck telescope is at:
http://cse.ssl.berkeley.edu/bmendez/pics/TRGB/Holmberg_II.jpg
Arp's image of this galaxy is one of his best, indicating a very good night atop Palomar mountain.
http://nedwww.ipac.caltech.edu/level5/Arp/Figures/big_arp268.jpeg
Arp's image was taken in blue light it appears to show the super hot blue stars recently formed in the galaxy.
Note that both the above images have south at the top, I oriented mine with north at the top.
This was taken January 21 UTC so I'm getting a bit more current in my processing!
14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME
Full image:
http://www.spacebanter.com/attachment.php?attachmentid=2494&stc=1
Rick
|
bill w
Postmaster
Reged: 03/26/05
Posts: 6475
Loc: southern california
|
|
awesome depth rick!
very cool looking galaxy
thanks for the write up
--------------------
-bill w
nexstar 8 GPS
canon 300D, Toucam Pro II
SXV-H9C, H9, SX Exview autoguider, SX-AO
FS 102 (OLV), FS60 CSV, 8" LX200R, G 11
http://whwastro.homestead.com/
image processing monitor calibrated to just differentiate darkest boxes:
|
Rick J
Pooh-Bah
Reged: 03/01/08
Posts: 1087
Loc: Mantrap Lake, MN
|
|
Thanks bill.
I'm surprised this is a virtually ignored member of the M81 group. Seems lots of imagers go after the other members of the group (at least northerners) but skip this one. Maybe it's because it doesn't have an IC or NGC number and gets overlooked. Something about such galaxies seems to scare away folks from even trying it. I can think of a lot of NGC and IC galaxies that are much harder targets than this one.
I think it one of my better Arp efforts. Everything seemed to work that night. I went a couple months with a loose set screw allowing the camera to go out of square causing problems. Even when it held square the light seal was lost so stray light was getting in and doing all sorts of harm. Also tilted slightly (at f/10 you can survive some tilt and stay in focus as the depth is rather large at that f ratio) the dust mots didn't quite line up on the flats adding to processing woes. This is one of the first images after I finally realized what was going on and tightened down that offending set screw. Due to the mounting method the camera was never in danger of coming off, just tilting and/or letting stray light in. Unfortunately I still have a bunch of Arps from that "loose screw" era to process. I keep putting them off. Wait long enough and it will be time to reimage them rather than fight the processing. Procrastination isn't all bad.
Rick
|
BrianFitz
Carpal Tunnel
Reged: 07/17/08
Posts: 1684
Loc: Northern California
|
|
Very cool Rick!!
--------------------
Fitz
Meade LX200R 10" F/10
Stellarvue Raptor 80ED
Meade 152ED APO US made
WO EP's / Televue diagonals
QHY8 / QHY5 / Philips SPC 900
20X80 Celestron / 7X50 Meade Binos
“Lots of "Dreams”
“The Skillful Illusionist Makes the Best Image"
|
|
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
[Re: 