M65 and M66 Galaxies


Object Type: Galaxy
Scope: C-9.25"
Exposure 180 minutes



M65 and M66 are about 36 million light years away.

M65 was discovered by Charles Messier and included in his Messier Objects list. However, William Henry Smyth accidentally attributed the discovery to Pierre Méchain in his popular 19th century astronomical work A Cycle of Celestial Objects (stating "They [M65 and M66] were pointed out by Méchain to Messier in 1780"). This error was in turn picked up by Kenneth Glyn Jones in Messier's Nebulae and Star Clusters. This has since ramified into a number of other books by a variety of authors.


The galaxy is low in dust and gas, and there is little star formation in it, although there has been some relatively recently in the arms. The ratio of old stars to new stars is correspondingly quite high. In most wavelengths it is quite uninteresting, though there is a radio source visible in the NVSS, offset from the core by about two arc-minutes. The identity of the source is uncertain, as it has not been identified visually, or formally studied in any published papers.


To the eye, M65's disk appears slightly warped, and its relatively recent burst of star formation is also suggestive of some external disturbance. Rots (1978) suggests that the two other galaxies in the Leo Triplet interacted with each other about 800 million years ago. Recent research by Zhiyu Duan suggests that M65 may also have interacted, though much less strongly. He also notes that M65 may have a central barit is difficult to tell because the galaxy is seen from an oblique anglea feature which is suggestive of tidal disruption.


Messier 66 (also known as NGC 3627) is an intermediate spiral galaxy about 36 million light-years away in the constellation Leo. It was discovered by Charles Messier in 1780. M66 is about 95 thousand light-years across with striking dust lanes and bright star clusters along sweeping spiral arms. M66 is part of the famous Leo Triplet, a small group of galaxies that also includes M65 and NGC 3628.

Gravitational interaction from its past encounter with neighboring NGC 3628 has resulted in:
An extremely high central mass concentration;
A high molecular to atomic mass ratio;
A resolved noncorotating clump of H I material apparently removed from one of the spiral arms.
This third result shows up visually as an extremely prominent and unusual spiral arm and dust lane structures as originally noted in the Atlas of Peculiar Galaxies.

All Rights Reserved (C) All Images Chanan Greenberg 2003 - 2020