Spiral Galaxy M66 (NGC 3627), type Sb, in Leo

in the Leo Triplett

Right Ascension: 11:20.2 (h:m)
Declination: +12:59 (deg:m)
Distance: 35000 (kly)
Size: 8 x 2.5 (min)
Visual Brightness: 8.9 (mag)
Apparent Dimension: 8x2.5 (arc min)
Discovered 1780 by Pierre Méchain.

M66, together with its neighbors M65 and NGC 3628, forms a most conspicuous triplet of galaxies, the Leo Triplett or M66 group, located at a distance of about 35 million light years.

M66 is considerably larger than its neighbor, M65, and has a well developed but not well defined central bulge, and is therefore classified Sb. Obviously its spiral arms are deformed, probably because of the encounters with its neighbors. They seem to be distorted and displaced above the plane of the galaxy. Note how one of the spiral arms seems to pass over the left side of the central bulge. Much dust is visible here, as well as a few pink nebulae, signs of star formation, near the end of one of the arms.

The discovery pf M65 and M66 is usually assigned to Pierre Méchain (Kenneth Glyn Jones, Burnham), although Messier doesn't acknowledge his friend's prior discovery in these cases, unlike for most of Méchain's findings, and the NGC doesn't credit Méchain.

Three supernovae have appeared in this galaxy:

• 1973R which was of type II and reached mag 15 was found on Dec 12, 1973.
• 1989B was discovered on Jan 31, 1989 and became as bright as mag 12.2 on Feb 1, 1989.
• 1997bs was discovered by the Lick Observatory Supernova Search Team as it occurred on April 15, 1997 at 13" west, 67" south of the galaxy's center and reached mag 17.0; this was of peculiar type IIn.

Halton Arp has included M66 in his Catalogue of Peculiar Galaxies as entry No. 16. Moreover, he assigned the number 317 to the Leo Triplett (M66 together with M65 and NGC 3628).

This image was obtained by David Malin with the Anglo Australian Telescope, and is copyrighted.