NGC 6946 Fireworks Galaxy

mudman · Post by **mudman** » Wed Jan 26, 2005 3:01 pm

Near the upper left hand corner of APOD 2005 Jan 25 is what appears to be a circular star cluster with an arm of NGC6946 wrapped around it. Are this part of NGC 6946? I haven't seen anything like this in looking at pictures of a couple of hundred different galaxies.

The Meal · Post by **The Meal** » Wed Jan 26, 2005 4:55 pm

Is it not the irregular dwarf galaxy UGC 11583?

~Neal

crosscountry · Post by **crosscountry** » Wed Jan 26, 2005 4:55 pm

mudman wrote:Near the upper left hand corner of APOD 2005 Jan 25 is what appears to be a circular star cluster with an arm of NGC6946 wrapped around it. Are this part of NGC 6946? I haven't seen anything like this in looking at pictures of a couple of hundred different galaxies.

it looks to me like a dwarf galaxy being "assimilated"

it could be a VERY large Globular cluster.

good question. I wonder what the pros think?

Dan Cordell · Post by **Dan Cordell** » Wed Jan 26, 2005 6:36 pm

It is in fact a part of the galaxy itself.

A likely scenario is that it is the site of an ancient supernova.

I will, however, point this thread out to Dr. Nemiroff, as I'm not completely sure myself.

mudman · Post by **mudman** » Fri Jan 28, 2005 4:36 am

The apparent dwarf galaxy seen near the upper left hand corner of APOD 2005 Jan 25 image of NGC 6946 is shown in two images isolated from NGC 6946 images at NOAO url http://www.noao.edu/outreach/aop/observers/n6946.html

Dan Cordell · Post by **Dan Cordell** » Sun Jan 30, 2005 5:12 pm

mudman wrote:The apparent dwarf galaxy seen near the upper left hand corner of APOD 2005 Jan 25 image of NGC 6946 is shown in two images isolated from NGC 6946 images at NOAO url http://www.noao.edu/outreach/aop/observers/n6946.html

Looks like I was right, the text references several supernovae occuring in that galaxy.

mudman · Post by **mudman** » Wed Feb 23, 2005 3:26 am

http://www.seds.org/messier/xtra/ngc/n6946.html lists eight supernovas observed in NGC 6946. Each supernova has a coordinate set. How is this coordinate system applied to an object such as NGC 6946? Any help will be appreciated.

mudman · Post by **mudman** » Tue Apr 05, 2005 6:02 am

On Jan 26 The Meal suggested the unusual formation noted in the upper left hand corner of APOD 2005 Jan 25 Fireworks galaxy might be "Is it not the irregular dwarf galaxy UGC 11583?"

It appears not, based on the following:

Companions and interactions in the NGC 6946 system
Authors: Pisano D.J.; Wilcots E.M.
Source: Monthly Notices of the Royal Astronomical Society, December 2000, vol. 319, no. 3, pp. 821-825(5)
covered three dwarf galaxies around NGC 6946: UGC 11583,. L149, and L150. ...
identified (from east to west) as L149 and UGC 11583
Our survey recovered two previously detected dwarf galaxies associated with NGC 6946, but otherwise found no signatures of interactions in the NGC 6946 system. The companions are small enough, and distant enough from NGC 6946 that they should have minimal effect on the main galaxy.

mudman · Post by **mudman** » Mon Apr 25, 2005 9:13 am

The 2005 April 15 RCW 79: Stars in a Bubble
http://antwrp.gsfc.nasa.gov/apod/ap050415.html

"In fact, this penetrating infrared picture reveals groups of new stars as yellowish points scattered along the bubble's edge. One remarkable group still lies within its own natal bubble at about 7 o'clock (lower left), ..."

This natal bubble suggests the same structure as previously noted.

Starship Asterisk*

NGC 6946 Fireworks Galaxy

NGC 6946 Fireworks Galaxy

Re: NGC 6946 Fireworks Galaxy

dwarf galaxy image

Re: dwarf galaxy image

a natal bubble