Ring Galaxy in Eridanus

Click here for higher-resolution versions:40% (1538x982) 65% (2500x1596) 100% (3846x2456)


NGC1291: This is a very nice example of the rather unusual "Ring Galaxy" structure (this one has a central bar--the very bright, roughly horizonat region in the middle of the core).

Nobody really knows how these things are formed. Some astronomers believe that ring galaxies are formed when a smaller galaxy passes through the center of a larger galaxy; because most of a galaxy consists of empty space, this "collision" rarely results in any actual collisions between stars. However, the gravitational disruptions caused by such an event could cause a wave of star formation to move through the larger galaxy. Other astronomers think that rings are formed around some galaxies when external accretion takes place. Star formation would then take place in the accreted material because of the shocks and compressions of the accreted material.

The ring contains many massive, relatively young blue stars, which are extremely bright. The central region contains principally old, red and yellow/red stars. This galaxy is about two-thirds the size as our own Milky Way galaxy, about 65,000 light years across; it is about 33 million light years from us.


Technical Information:

LRGB: 1215:315:525:465; All channels are the integration of 15-minute exposures through Astrodon filters. All images unbinned.

Equipment: 14.5" RCOS at about f/9, and an SBIG STL-11000M with internal filter wheel (Astrodon filter set), guided by a MOAG/AO-L combination, all riding on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP, working in concert with TheSky v6.

Processing: All images calibrated (darks and dawn flats), aligned and combined in Pixinsight. Color combine in Pixinsight. Gradient taming in Pixinsight. Finish work (curves and levels, adjustment of contrast, High Pass Filter/Layer Mask, and some sharpening of the luminance layer) was done in Photoshop CS5.

Location: Data acquired remotely from Fair Dinkum Skies, Moorook, South Australia.

Date: Images taken on many nights in September, October and November 2014. Image posted March 6, 2015.

CCD Chip temperature: Mostly -15C; a few at -5C

Copyright 2014, 2015 Mark de Regt

hosting forum
Hit Counter