About the Subject

NGC 3628, sometimes called the 'Hamburger Galaxy' or 'Sarah's galaxy' is the dimmest galaxy of the famed Leo Triplet. It is about thirty-five million light years from Earth and is classified as an unbarred spiral, though some suspect it is actually a barred spiral with the bar seen end-on. The presence of a bar may account for the relatively faint 'x' shaped bulge. A dust lane in the outer parts of the spiral arms almost perfectly bisects NGC 3628.

In 1956, Fritz Zwicky of Cal Tech, while reviewing photographic plates taken with the 48" Schmidt Camera on Mt. Palomar, noticed a faint extension roughly ten arc minutes in length to the east of NGC 3628. In a later photographic plate taken in 1974 by Kormendy and Bahcall using the 200" Hale telescope, then the largest telescope in the world, the plume was seen to extend for roughly forty arc minutes not ten. That corresponds to an actual length of roughly 260,000 ly given current distance measurements to NGC 3628. Follow-up studies in the late 70's were made to try and determine the source of this plume. It is believed that the plume is a 'tidal tail' of stars stripped out of NGC 3628 from a close encounter with M66, one of the other three galaxies in the Leo Triplet. Computer simulations suggest the interaction was roughly 800,000,000 years ago. The tidal tail includes four distinct star forming regions, as determined by Chromey et al in a 1995 study using the 0.6m Burrell Schmidt telescope at Kitt Peak.

Typically, this galaxy is framed to include the other members of the Leo Triplet. However, I wanted to focus on the tidal tail and rich background of distant galaxies in Leo, so I framed and cropped this image without M65 and M66