Messier 104: Sombrero Galaxy

The Sombrero Galaxy is one of the most recognizable galaxies in the sky: a bright, swollen core crossed by a dark band of dust, like a wide-brimmed hat seen from the side. It sits in southern Virgo near Corvus and is bright enough to show its shape in a modest telescope.

What it is

M104 is a spiral galaxy tilted only a few degrees from edge-on. What makes it striking is its huge central bulge of old stars, much larger relative to the disk than in most spirals, and the thick lane of dust that rings the disk and cuts across the bulge in silhouette. It lies about 28 million light-years away, and its 9′ length corresponds to roughly 70,000 light-years. Hubble images show a very large family of globular clusters swarming around it, far more than the Milky Way has, and astronomers have found evidence of a very massive black hole at its center.

When to see it

M104 is a spring galaxy, highest around midnight in early April and placed well in the evening from April into early June. Because it lies south of the celestial equator, it never climbs very high from mid-northern latitudes: from about 40°N it reaches roughly 38° above the southern horizon. Observers in the Southern Hemisphere see it much higher; from 35°S it reaches about 67°.

How to find it

The first route starts at Porrima (Gamma Virginis), the third-magnitude star at the center of the Y of Virgo: M104 lies about 10° due south of it. The second starts in Corvus, the small four-sided pattern below Virgo. Find Algorab (Delta Corvi), the northeastern corner of the quadrilateral. M104 is about 5.5° north-northeast of Algorab.

What you will see

In binoculars from a dark site, M104 is a small, distinctly elongated glow with a brighter center, still visible from the suburbs. A 70–100 mm telescope shows an oval glow with a bright core, and on a steady night a hint that one side is cut short by the dust lane. A 150–200 mm telescope shows the dust lane clearly as a thin dark line running just south of the core, with the bright bulge rising above it. Larger scopes show the lane extending out to the tips of the disk. Filters do not help.

History

Pierre Méchain discovered the galaxy on May 11, 1781. It was not in the catalog Messier published that year, but Messier wrote it into his personal copy by hand. In 1921 Camille Flammarion found that note and identified the object with NGC 4594, and it became M104, the first of the seven objects (M104 to M110) added in the 20th century from Messier's and Méchain's records. In 1912 Vesto Slipher measured its spectrum and found it receding at a remarkable speed, early evidence that the "spiral nebulae" were far beyond our own galaxy.