Go Back   IceInSpace > Images > Deep Space
Register FAQ Calendar Today's Posts Search

Reply
 
Thread Tools Rate Thread
  #1  
Old 04-09-2011, 04:15 AM
Ken Crawford's Avatar
Ken Crawford (KenC)
Ken Crawford

Ken Crawford is offline
 
Join Date: Jan 2010
Location: Camino, Ca USA
Posts: 212
Hula Hoop Galaxy

Hello,

We now know that an important part of galaxy formation is the fact that many larger galaxies tear apart and absorb smaller galaxies called Dwarfs. During the merger process, the dwarf galaxy orbits around and sometimes through the main galaxy, leaving a trail of debris around the larger galaxy. Because this galaxy is about 55 Mpc (179 million light years) we are lucky enough to see the possible tidal star streams. They appear like a hula hoop around the core of the main galaxy. These loops are very well defined and are thought to be at least two orbits of a dwarf galaxy.

This target is getting to the limits of my imaging system but you can just start to make out a faint dust lane around the core.

Click to zoom and pan and don't forget the full screen button.

http://www.imagingdeepsky.com/Galaxi...11/NGC7711.htm

Thanks for taking the time to look . . .

Kindest Regards,
Reply With Quote
  #2  
Old 04-09-2011, 07:04 AM
Alchemy (Clive)
Quietly watching

Alchemy is offline
 
Join Date: Jul 2007
Location: Yarra Junction
Posts: 3,044
Interesting image, always nice to see the unusual and different, the negative really shows the tidal movement well.
Reply With Quote
  #3  
Old 04-09-2011, 01:08 PM
bokglob's Avatar
bokglob (Darrell)
ph0t0n3la5t3r

bokglob is offline
 
Join Date: Feb 2008
Location: brisbane australia
Posts: 256
Thats a background fuzzy with background fuzzies! Incredible, 179 million years back and thats close in the scheme of things! Intergalactic perspective makes my brain hurt Thanks for the buzz!
Reply With Quote
  #4  
Old 04-09-2011, 05:04 PM
John Hothersall's Avatar
John Hothersall
Registered User

John Hothersall is offline
 
Join Date: Apr 2007
Location: Thornlands, Brisbane.
Posts: 1,346
Thats an interesting structure that a big scope can really show well, great colours for such a far off galaxy.

John.
Reply With Quote
  #5  
Old 04-09-2011, 07:48 PM
Lester's Avatar
Lester
Registered User

Lester is offline
 
Join Date: Jan 2006
Location: E.P. S.A.
Posts: 4,963
Wonderful view, and one I have not seen before. Thanks Ken. All the best.
Reply With Quote
  #6  
Old 04-09-2011, 09:51 PM
Ross G
Registered User

Ross G is offline
 
Join Date: Apr 2007
Location: Cherrybrook, NSW
Posts: 5,013
Thanks Ken,

An amazing photo of a new object for me.



Ross.
Reply With Quote
  #7  
Old 05-09-2011, 04:02 AM
Ken Crawford's Avatar
Ken Crawford (KenC)
Ken Crawford

Ken Crawford is offline
 
Join Date: Jan 2010
Location: Camino, Ca USA
Posts: 212
Thanks for the kind words, I know this is not a grand galaxy but it is interesting to look back in time at the morphology of it.

Kindest Regards,
Reply With Quote
  #8  
Old 05-09-2011, 07:11 AM
lebowski's Avatar
lebowski (Paolo)
Registered User

lebowski is offline
 
Join Date: Dec 2009
Location: rome
Posts: 114
Quote:
Originally Posted by Ken Crawford View Post
Thanks for the kind words, I know this is not a grand galaxy but it is interesting to look back in time at the morphology of it.

Kindest Regards,
very interesting structure.
Ciao Ken
Reply With Quote
  #9  
Old 05-09-2011, 08:37 AM
SkyViking's Avatar
SkyViking (Rolf)
Registered User

SkyViking is offline
 
Join Date: Aug 2009
Location: Waitakere Ranges, New Zealand
Posts: 2,260
That's very nice and an interesting view of the structure in the negative image, it really shows well. It reminds me of the 'Atoms for Peace' galaxy.
Reply With Quote
  #10  
Old 05-09-2011, 09:12 AM
strongmanmike's Avatar
strongmanmike (Michael)
Highest Observatory in Oz

strongmanmike is offline
 
Join Date: May 2006
Location: Canberra
Posts: 17,689
Quite a bit to see considering its distance Ken, would normally be little more than an elongeted smudge so a great capture there really

Mike
Reply With Quote
  #11  
Old 05-09-2011, 06:56 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 18,185
Awesome Ken.

You caught those faint tidal streams very brightly.

How are you finding the U16M compared to the U09000?

Greg.
Reply With Quote
  #12  
Old 06-09-2011, 12:49 PM
Ken Crawford's Avatar
Ken Crawford (KenC)
Ken Crawford

Ken Crawford is offline
 
Join Date: Jan 2010
Location: Camino, Ca USA
Posts: 212
Quote:
Originally Posted by gregbradley View Post
Awesome Ken.

You caught those faint tidal streams very brightly.

How are you finding the U16M compared to the U09000?

Greg.
Thanks Greg,

I am finding there is more information that is useful for decon (you need good sampling) so I was able to be recover this thin and faint dust lane because of it. But I do miss the sensitity of the u9000 larger pixels as it does do deeper faster. So I am finding I need to image about 20 - 25% longer to get the same S/N.

The great thing is that both cameras have the same body style so in the winter when the seeing is not quite as good for me, I can throw the u9000 on my 10 slot filter wheel with just a few bolts. It is very easy to swap cameras now based on what I am imaging and the seeing conditions.

Regards,
Reply With Quote
  #13  
Old 06-09-2011, 01:48 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 18,185
Interesting Ken. Well you've got the best of both worlds there.

Greg.

Quote:
Originally Posted by Ken Crawford View Post
Thanks Greg,

I am finding there is more information that is useful for decon (you need good sampling) so I was able to be recover this thin and faint dust lane because of it. But I do miss the sensitity of the u9000 larger pixels as it does do deeper faster. So I am finding I need to image about 20 - 25% longer to get the same S/N.

The great thing is that both cameras have the same body style so in the winter when the seeing is not quite as good for me, I can throw the u9000 on my 10 slot filter wheel with just a few bolts. It is very easy to swap cameras now based on what I am imaging and the seeing conditions.

Regards,
Reply With Quote
  #14  
Old 12-09-2011, 09:52 AM
madbadgalaxyman's Avatar
madbadgalaxyman (Robert)
Registered User

madbadgalaxyman is offline
 
Join Date: Mar 2011
Location: Brisbane
Posts: 936
That's one strange galaxy, Ken.

This galaxy, overall, seems asymmetric and disturbed, and not to be in a settled state. (the overall asymmetry is far in excess of what is normal for mildly disturbed galaxies)

I can't recall seeing anything like this morphology, though I am familiar with the morphologies of a large fraction of the NGC/IC galaxies.

I'll have to "cogitate" about this one, and also consult the literature.
Reply With Quote
  #15  
Old 12-09-2011, 11:46 PM
Ken Crawford's Avatar
Ken Crawford (KenC)
Ken Crawford

Ken Crawford is offline
 
Join Date: Jan 2010
Location: Camino, Ca USA
Posts: 212
Quote:
Originally Posted by madbadgalaxyman View Post
That's one strange galaxy, Ken.

This galaxy, overall, seems asymmetric and disturbed, and not to be in a settled state. (the overall asymmetry is far in excess of what is normal for mildly disturbed galaxies)

I can't recall seeing anything like this morphology, though I am familiar with the morphologies of a large fraction of the NGC/IC galaxies.

I'll have to "cogitate" about this one, and also consult the literature.
Thanks! If you wish to read a bit about this galaxy and it's streams, here is the paper from a steam hunting team. They are using the SDSS data to detect them. I have shot two of there detections so far. I sent them my results and they were pretty impressed as they are doing follow-up with a 2.2 meter system and I am just about as deep. They are just about ready to release a paper with many more detects (lots of new targets coming!)

http://arxiv.org/PS_cache/arxiv/pdf/...102.2905v1.pdf

Regards,
Reply With Quote
  #16  
Old 13-09-2011, 12:24 AM
renormalised's Avatar
renormalised (Carl)
No More Infinities

renormalised is offline
 
Join Date: Apr 2008
Location: Townsville
Posts: 9,698
Post

Quote:
Originally Posted by madbadgalaxyman View Post
That's one strange galaxy, Ken.

This galaxy, overall, seems asymmetric and disturbed, and not to be in a settled state. (the overall asymmetry is far in excess of what is normal for mildly disturbed galaxies)

I can't recall seeing anything like this morphology, though I am familiar with the morphologies of a large fraction of the NGC/IC galaxies.

I'll have to "cogitate" about this one, and also consult the literature.
Could be a case of our angle of view onto this object, or, it's taken a hit from something else that we haven't yet identified at some time in the past. Also, another reason...how big was the interacting galaxy that produced the "hula hoop" star streams and the rest of the debris around this galaxy?? It may have been bigger than we suspect. What was the geometry of the collision etc etc.

How many papers have been published about this galaxy and/or similar galaxies and their morphologies??.

BTW, Ken....nice piccie
Reply With Quote
  #17  
Old 13-09-2011, 08:58 AM
Ken Crawford's Avatar
Ken Crawford (KenC)
Ken Crawford

Ken Crawford is offline
 
Join Date: Jan 2010
Location: Camino, Ca USA
Posts: 212
Quote:
Originally Posted by renormalised View Post
Could be a case of our angle of view onto this object, or, it's taken a hit from something else that we haven't yet identified at some time in the past. Also, another reason...how big was the interacting galaxy that produced the "hula hoop" star streams and the rest of the debris around this galaxy?? It may have been bigger than we suspect. What was the geometry of the collision etc etc.

How many papers have been published about this galaxy and/or similar galaxies and their morphologies??.

BTW, Ken....nice piccie

It was most likely a dwarf galaxy and it is believed to have made at least 2 orbits. There are several N-Body simulations that show how these interactions work. Our Star Stream team has several that were done. These are some that are currently being studied . . . .

Here is another stream that I have captured but with only one "loop" but a simular type orbit. It's stream is much fainter and harder to capture.

http://www.imagingdeepsky.com/Galaxi...84/NGC4684.htm

http://www.imagingdeepsky.com/Streams.html

Kindest Regards,
Reply With Quote
  #18  
Old 13-09-2011, 01:14 PM
madbadgalaxyman's Avatar
madbadgalaxyman (Robert)
Registered User

madbadgalaxyman is offline
 
Join Date: Mar 2011
Location: Brisbane
Posts: 936
Thank you, Ken, for the link to the paper.
This is a tough object, and you have done an excellent job on it.

This paper is an excellent compilation of deep images of various galaxies.....and it could be useful for testing the ability of imagers to reach very deep in their astronomical images.
"Image deeper, sharper, or wider, and you are sure to turn up something new"

I didn't find much about this galaxy in the astronomical papers archive at http://adsabs.harvard.edu , so it has had little attention from professional astronomers, to date.
S.M. Kent provided some data about this galaxy in the 1984 ApJS, and Googling on this galaxy will find some NIR and Optical imaging data by Peletier and Balcells.

For comparison purposes, I attach the g+r+i bands composite image from SDSS (downloaded from Skyserver DR8) :

Click image for larger version

Name:	N7711_SDSS.jpg
Views:	16
Size:	67.6 KB
ID:	100527

This galaxy is nominally an S0 or Very Early Sa galaxy, though it deserves to be said that the S0 morphological class is a "broad church" which encompasses galaxies with giant bulges and minimal disks as well as objects which are more similar to spiral galaxies but without most of the usual ISM and star formation. (A lot of galaxies which are "not quite S0" and "not quite Sa" end up in the S0-a (S0/a) class, which is absolutely the rubbish bin of the Hubble Sequence, as it is negatively defined)
But traditional Hubble classification methods classify only the structure of a 2-D image, and sometimes tell us little about the underlying three-dimensional galactic morphology.

The surface brightness of this galaxy is very modest indeed, judged from the faintness of this galaxy in DSS images. Perhaps the highest contrast of the DSS images of it is at:

http://server1.wikisky.org
(while not the sharpest DSS images, these seem to be at higher contrast than usual)

See also the color composite image at Aladin, which is my favourite version of DSS:

http://aladin.u-strasbg.fr/AladinPreview

I do agree with our mutual friend "renormalised" that the perturbation of this galaxy looks like it could have originated with a perturbing object of significant mass.

The degree of asymmetry or lopsidedness in the apparent (two-dimensional) distribution of the stellar light is remarkably high. The observed morphology is indeed quite singular,at least if we compare the observed morphology to examples of disk galaxies that are not an immediate product of a major merger between two galaxies.
This is not one of those galaxies in which there is a large apparent optical asymmetry caused by OB stars and HII Regions without there being a corresponding asymmetry in the underlying mass-dominant Old Stellar Population which is better traced in the NIR regime. (Unfortunately the NIR image from the 2MASS survey is too faint to show anything meaningful about this galaxy.)

There is little star formation apparent in this galaxy, judging from the lack of FUV emission detected in the GALEX image of it. Its B-V optical color (within the effective aperture) of 1.03 (in Prugniel and Heraudeau's catalog of aperture photometry) is redder than that of any normal spiral galaxy, and in fact this color value is similar to the optical color of an elliptical galaxy!

This low apparent Star Formation Rate and red optical color strengthens the case for this galaxy being classified as an S0.
However, the morph. is so peculiar, that perhaps an orthodox Hubble type is not applicable.

Last edited by madbadgalaxyman; 13-09-2011 at 01:20 PM. Reason: more info
Reply With Quote
  #19  
Old 13-09-2011, 11:13 PM
Stevec35 (Steve)
Registered User

Stevec35 is offline
 
Join Date: Aug 2010
Location: Canberra
Posts: 3,654
I think I already commented on this on another forum but excellent work as always Ken.

Cheers

Steve
Reply With Quote
  #20  
Old 19-09-2011, 01:46 PM
marco's Avatar
marco (Marco Lorenzi)
Registered User

marco is offline
 
Join Date: Aug 2009
Location: Singapore
Posts: 933
Nice image Ken of what I believe to be a very faint object. It looks like somebody chopped away the right arms of a spiral galaxy Thanks for sharing!

Clear Skies
Marco
Reply With Quote
Reply

Bookmarks


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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 09:16 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Advertisement
Astrophotography Prize
Advertisement
Bintel
Advertisement