Stellar streams around the galaxy M63 (NGC 5055) are the remnants of a satellite galaxy that was disrupted by the large spiral. Mouse over to view inverted image.

RCOS 20- inch, SBIG STL-11000
405 minutes Luminance, 90 minutes Red, 54 minutes Green and 108 minutes Blue (All 1X1)

Image copyright ©2005- 2010 R Jay GaBany

A Petal of the Sunflower:

Discovery of a Stellar Tidal Stream in the Halo of Messier 63 (NGC 5055)

An investigation by:
We report the discovery of a very faint, giant arc-loop feature in the halo of the nearby spiral galaxy Messier 63 (NGC 5055). This feature is the stellar stream of a disrupted dwarf satellite galaxy.

This faint feature was first detected in early photographic studies by van der Kruit in 1979 but it was unknown if the faint structure was associated with Messier 63 (NGC 5055) or interveening Milky Way galactic cirrus like that contaminating our view of Messier 81 (NGC 3031). Our study realized it was the result of a minor merger between the large spiral and a much smaller satellite galaxy companion. Our initial observations were obtained from deep wide field images exposed through a modest telescope with an aperture of only 0.16 meters (106 milimeters).

It's presence has been confirmed in deep images taken with the 0.5 meter telescope of the BlackBird Remote Observatory (seen here) and the 0.8 meter telescope of the McDonald Observatory. This arc-like structure around the disk of the galaxy has a very low surface brightness and extends 14.0' (~29 kpc projected) from its center with a projected width of 1.6' (~3.3 kpc). The stream’s morphology is consistent with a giant "great-circle" type stellar stream that originated from the accretion of a dwarf satellite sometime within the last 5 billion years. The progenitor satellite’s current position and final fate are unknown, although the color of the stream’s stars are consistent with dwarfs in the Local Group.

Through our photometric study, we found other low surface brightness "plumes" that, while probably unrelated to the tidal stream, could be extended spiral features related to the galaxy’s complex spiral structure. We are able to differentiate between features related to the tidal stream and faint, blue, extended features in the outskirts of the galaxy’s disk previously detected by the GALEX satellite.

With its highly warped HI gaseous disk, Messier 63 (NGC 5055) represents one of several recently discovered examples of an isolated spiral galaxy with a warped disk showing strong evidence of an ongoing minor merger.

Our team's complete results and full documentation are available for download here.

Read the background article: Spiral Galaxies devour their satellites

Other popular images

Home page