Texas Astronomical Society

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Constellations of the Month

by Rick Raasch

VIRGO

It's galaxy time, folks. The constellation of Virgo is the center of the closest large cluster of galaxies, and can easily take up several evenings of observing time. While the galaxies in Ursa Major (last month's constellation of the month) are 10-40 million light years away, the galaxies of Virgo are about twice as distant at about 70 million light years. As such, these galaxies show a lot less detail. But what they lack in quality, they make up in quantity. In some areas, it is difficult to move a whole telescopic field of view without seeing one or more galaxies. A good star atlas is a must in this region for identifying all the galaxies visible in a telescope of moderate aperture. While I'm only going to be describing some of the brighter members here, I encourage all to try navigating this area. It would be hard not to improve your observing skills by meeting this challenge head-on.

M-58 With dimensions of about 5'x2', this is one of the larger galaxies in this region. It is spindle-shaped, oriented NE-SW, and has a broadly concentrated center. There is a relatively bright star nearby to the west.

M-61 This galaxy is a face-on spiral, about 6'x4', oriented NNE-SSW. It is fairly even in brightness except for a stellar nucleus and some faint mottlings on its eastern and western sides.

M-84,M-86 These relatively bright galaxies are very similar in appearance, and are visible in the same low-power field of view. M-84 is round, about 3' in diameter, has a large 1' diameter core, and a stellar nucleus. M-86 is larger (about 4' in diameter), and fainter, and also has a stellar nucleus.

M-87 This is a very bright galaxy, about 4' in diameter, with a large core and non-stellar nucleus.

M-104 The Sombrero Galaxy. This is one of the finest showpiece objects in the sky. This beautiful edge-on galaxy is 8-10'x2', oriented E-W, and has an obvious central bulge, with a distinct dark lane running the length of the galaxy. This is an object which should not be missed.

NGC 4179 This galaxy is about 3’x1', extended NW-SE, with very thin tapered edges. It is sharply brighter to the center with a stellar core.

NGC 4753 Rather bright, this galaxy is about 4’x2.5', oriented ENE- WSW. It is broadly concentrated to the center, with a stellar nucleus. At times, I noticed dark markings at the NE side.

NGC 4762 This galaxy reminds me of a smaller version of the well known edge-on galaxy, NGC 4565. It is about 4’x0.7', oriented NE-SW, and averted vision hints at a dust lane.

Next Month: Scorpius