A Space & astronomy forum. SpaceBanter.com

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » SpaceBanter.com forum » Others » Astro Pictures
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

ASTRO: NGC 1637 a nice galaxy rarely seen for some reason



 
 
Thread Tools Display Modes
  #1  
Old May 12th 14, 09:17 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
external usenet poster
 
Posts: 3,085
Default ASTRO: NGC 1637 a nice galaxy rarely seen for some reason

NGC 1637 is a rather nearby somewhat "sloshed" galaxy in northeastern
Eridanus. "Sloshed in the sense of asymmetric much as a raw egg becomes
sloshed back and forth in a fry pan with the yoke off center. I've seen
it called a three arm galaxy though to me it has only two arms that come
off a bar. The north one short going 180 degrees and not expanding all
that far from the core though it ends in an odd straight segment. The
other however makes a huge 360 degree arc passing over the much smaller
northern arm. Much of this arm is rather red in color indicating its
stars are rather old. How such an old arm without new star formation to
keep the density wave going that forms the arm can exist for so long is
a puzzle but one many red spirals have that are even older than this
galaxy.

Redshift puts the galaxy at 31 million light-years. Pretty close by my
standards. Redshift at such a close distance can be very misleading.
NED lists 21 non redshift measurements for it that have a median value
of 32 million light-years. Very close to the redshift value. Also
large telescopes can resolve its brighter stars indicating the distance
is likely correct. The bright region of the galaxy is about 24,000
light-years in diameter assuming the 31 million light-year distance.
Including the faint halo more than doubles its size to 55,000 light-years.

NGC 1637 was discovered by William Herschel on February 1, 1876 with a
18.7" reflector. It is one of the second Herschel 400 objects so made
my list for both being unusual and being on that listing of the second
400 in that AL observing program.

Seen faintly, the galaxy has a huge halo around it that is quite blue
and thus contains mostly very new stars. Most images of this galaxy
fail to pick up this as it requires a lot of exposure time, a lot more
than I gave it. I saw a hint of it when I started to process the image
but wasn't going to try and bring it out as it would be very noisy.
Then I remembered an article in the March, 2014 issue of Astronomy
Magazine (the American magazine not the English magazine of the same
name) by Adam Block explaining a Photoshop technique I'd not seen before
for bringing up such plumes without increasing noise significantly. It
is very quick and easy to apply. Nice to add a new trick to my bag of
processing tricks.

This is yet another field in an area little studied for its galaxies.
While there are a lot of background galaxies only 3 had any distance
data so the annotated image is rather sparse.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

Attached Thumbnails
Click image for larger version

Name:	NGC1637L4X10RGB2X10.JPG
Views:	245
Size:	367.9 KB
ID:	5101  Click image for larger version

Name:	NGC1637L4X10RGB2X10ID.JPG
Views:	113
Size:	167.4 KB
ID:	5102  Click image for larger version

Name:	NGC1637L4X10RGB2X10CROP.JPG
Views:	36
Size:	153.9 KB
ID:	5103  
Ads
  #2  
Old May 12th 14, 07:56 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: NGC 1637 a nice galaxy rarely seen for some reason

Rick,

that's a good one indeed. It is on my list, but at -2deg I can't reach it
from my rooftop terrace.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

NGC 1637 is a rather nearby somewhat "sloshed" galaxy in northeastern
Eridanus. "Sloshed in the sense of asymmetric much as a raw egg becomes
sloshed back and forth in a fry pan with the yoke off center. I've seen
it called a three arm galaxy though to me it has only two arms that come
off a bar. The north one short going 180 degrees and not expanding all
that far from the core though it ends in an odd straight segment. The
other however makes a huge 360 degree arc passing over the much smaller
northern arm. Much of this arm is rather red in color indicating its
stars are rather old. How such an old arm without new star formation to
keep the density wave going that forms the arm can exist for so long is
a puzzle but one many red spirals have that are even older than this
galaxy.

Redshift puts the galaxy at 31 million light-years. Pretty close by my
standards. Redshift at such a close distance can be very misleading.
NED lists 21 non redshift measurements for it that have a median value
of 32 million light-years. Very close to the redshift value. Also
large telescopes can resolve its brighter stars indicating the distance
is likely correct. The bright region of the galaxy is about 24,000
light-years in diameter assuming the 31 million light-year distance.
Including the faint halo more than doubles its size to 55,000 light-years.

NGC 1637 was discovered by William Herschel on February 1, 1876 with a
18.7" reflector. It is one of the second Herschel 400 objects so made
my list for both being unusual and being on that listing of the second
400 in that AL observing program.

Seen faintly, the galaxy has a huge halo around it that is quite blue
and thus contains mostly very new stars. Most images of this galaxy
fail to pick up this as it requires a lot of exposure time, a lot more
than I gave it. I saw a hint of it when I started to process the image
but wasn't going to try and bring it out as it would be very noisy.
Then I remembered an article in the March, 2014 issue of Astronomy
Magazine (the American magazine not the English magazine of the same
name) by Adam Block explaining a Photoshop technique I'd not seen before
for bringing up such plumes without increasing noise significantly. It
is very quick and easy to apply. Nice to add a new trick to my bag of
processing tricks.

This is yet another field in an area little studied for its galaxies.
While there are a lot of background galaxies only 3 had any distance
data so the annotated image is rather sparse.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Is there a reason why 39 should give a bad hair day and 32 nice curls? [email protected] Astronomy Misc 6 April 8th 14 10:15 PM
ASTRO: NGC 3344 Another rarely seen face on spiral galaxy Rick Johnson[_2_] Astro Pictures 1 November 13th 13 10:28 PM
ASTRO: NGC 3346 A rarely imaged, detailed, face on blue galaxy Rick Johnson[_2_] Astro Pictures 1 November 13th 13 10:25 PM
ASTRO: UGC 9240/DDO190 A rarely imaged nearby dwarf galaxy Rick Johnson[_2_] Astro Pictures 2 November 13th 13 10:02 PM
ASTRO: NGC 5005 Another rarely imaged galaxy Rick Johnson[_2_] Astro Pictures 2 October 27th 13 10:53 PM


All times are GMT +1. The time now is 01:42 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright 2004-2017 SpaceBanter.com.
The comments are property of their posters.