Leo Triplet

A fascinating group of three galaxies, two of them Messier objects, in the Leo Constellation, the three galaxies of the Leo Triplet reside around 35 million light years away. They each demonstrate different facets of galactic evolution.

Messier 65 (M65) (lower left) is a rather quiescent, largely undisturbed spiral galaxy. M65’s population of around 200 billion stars primarily comprises older stars because there is little gas or dust left for new star formation.

Messier 66 (M66) (upper left), however, shows evidence of having been distorted in the past by an encounter with another galaxy—probably one of the other two in the triplet. The largest of the three, it’s spiral arms are not uniform and its core has been moved off center due to some gravitational interaction with another galaxy. And unlike M65, it is undergoing a high rate of star formation.

NGC 3628 (upper right), commonly known as the Hamburger Galaxy, appears directly edge-on to us. Scientists believe it is a barred spiral galaxy because it shows a peanut (or X-shaped) bulge in the center. This is indicative of the effects of a wide bar of stars in the galaxy’s center. Unfortunately, this image was not taken under a dark enough sky or exposed for long enough to definitively reveal this peanut structure, although there is a tiny hint of it in the image. The galaxy also has a long tidal tail extended to the east from its northeastern corner. That is very faint and is not visible at all in the image. But my friend Daniel Stern has captured an excellent image of this galaxy that shows both features in great detail.