Deep-Sky Objects in Virgo

Virgo Cluster of Galaxies
Image Credit: Virgo Cluster of Galaxies by Rogelio Bernal Andreo

Virgo is the 2nd largest of the 88 recognized constellations, and the biggest of the zodiacal constellations, taking up an area of 1,294.43 square degrees of the southern celestial sky. The brightest star in Virgo is Spica (Alpha Virginis), a multi-star system with a combined apparent magnitude of +0.98.

Virgo is visible from latitudes of between +80° and -80°, although best viewed in the northern hemisphere at about 9 PM Local Time during the month of May, when it is highest in the sky. Nevertheless, Virgo remains visible up to about the middle of September before it becomes lost in the Sun’s glare by early twilight. Look for Virgo between the constellations Leo to its west and Libra to its east.

Virgo contains an impressive 11 Messier objects, as well as a large number of deep-sky objects, including many galaxies and galaxy clusters, the most notable of which are briefly explored in this list.

Virgo Cluster

Located about 54 million light years away, the Virgo Cluster is at the heart of the Virgo Super cluster of Galaxies that includes the 30 or so members of the Local Group of Galaxies, which in turn contains the Milky Way and Andromeda galaxies. All told, the Virgo Super cluster has between about 1,300 and 2,000 members, which also spill over into the constellation Coma Berenices. The image of the Virgo Cluster at the top of the page clearly shows the diffuse light that permeates the entire group, as well as M87, its biggest member seen towards the photo’s centre.

Image Credit: F. Espenak

Messier 49 (M49, NGC 4472)

This large elliptical galaxy is located about 56 million light years away, and even from this vast distance, it is the most luminous member of the Virgo Cluster with an apparent visual magnitude of 9.4, and naturally was the first galaxy in the cluster to be discovered by Charles Messier in February of 1771.

M49 is remarkable in several ways; apart from the fact that it is disrupting a smaller dwarf galaxy (UGC 7636, but not shown here), this galaxy contains around 5,900 massive, 10-billion-year old globular clusters, as opposed to the few hundred globular clusters in and around the Milky Way. M49 is also thought to contain a 565-solar-mass black hole in its core and two suspected, one-solar-mass black holes that are both thought to have formed when two massive stars collapsed. One supernova, designated SN 1969Q, was recorded in the galaxy in June of 1969. Look for M49 about 4 degrees to the southwestward of the star Epsilon Virginis.

Messier 58 (M58, NGC 4579)

NGC 4579
Image Credit: NASA/JPL-Caltech/R. Kennicutt and the SINGS Team

Located about 62 million light years away, M58 is a barred spiral galaxy with an apparent visual magnitude of 10.5, which makes it one of the most luminous galaxies in the whole of the Virgo Cluster of galaxies. Nevertheless, its active galactic nucleus has a low luminosity, with the galaxy as a whole categorized as “anemic”, meaning that there is a low contrast between its spiral arms and disk, or the region where most of the galaxy’s stars lie and create a bulge.

In January and June of 1998, there were two supernova events recorded in M58, designated SN 1988A and SN 1989M, respectively.

Despite its huge distance, M58 is visible using large binoculars, while a small telescopes will show the galaxy’s bright centre. A 4-inch or larger telescopes will then reveal its halo, while an 8-inch telescope will resolve part of the galaxy’s bar-shaped structure.

Messier 87 (M87, NGC 4486)

Image Credit: J. A. Biretta et al., Hubble Heritage Team, NASA

This super massive elliptical galaxy located about 53.5 light years away is considered the most massive galaxy in the Local Universe, which is a region of space around 2 billion light years across. With an apparent magnitude of 9.59, it is also the second brightest member of the Virgo Cluster, and one of the most luminous radio sources yet discovered. Based on the proper motions of several planetary nebulae that are “trapped” between M87 and the relatively close-by M68, the two galaxies are approaching each other, and they will likely merge in the far distant future.

M87 is classified as a type-cD galaxy, which means that it is a supergiant D-class galaxy that has an enormous halo of stars around an elliptical core, which is in turn surrounded by a large diffuse, but dust-free gaseous envelope. The blue streak shown in the image opposite is a jet of material and energy that is being blasted into space from the galaxy’s core; there is another jet blasting in the opposite direction, but the disc of the galaxy obscures this jet.

M87 is an easy target even for small telescopes, so look for it along an imaginary line drawn from the star Epsilon Virginis to the bright star Denebola in Leo, near the Virgo-Leo border.

Sombrero Galaxy (M104, NGC 4594)

Sombrero Galaxy
Image Credit: Lowell Observatory

Located only about 29.3 million light years away, M104 has an apparent visual magnitude of 9.98, and is a firm favorite among amateur observers. The prominent dust lane that encircles the galaxy and its nearly face-on aspect, however, makes it difficult to discern its structure with amateur-level equipment, but most investigators believe the galaxy to be an unbarred spiral. Based on its luminosity in X-ray frequencies, and the high velocities at which many stars orbit the galactic nucleus, M104 is thought to contain a billion-solar-mass black hole in its core.

The galaxy’s enormous central bulge that contains between 1,200 and 2,000 large globular clusters makes M104 an easy target for amateur telescopes, so look for it in the southern reaches of the constellation, about 11.5 degrees to the westward of the star Spica.

3C 273

3C 273
Image credit: Hubble Space Telescope’s Advanced Camera for Surve

While many quasars (quasi-stellar radio sources) have been discovered in the recent past, 3C 273, located only about 2.4 billion light years away, was not only the first extragalactic X-ray source to be discovered in 1970, but it is also the nearest and most luminous quasar in the entire sky. In fact, with an absolute magnitude of −26.7, if 3C 273 were placed at the same 33 light year distance as Pollux in Gemini, it would appear almost as bright as the Sun.

Needless to say, 3C 273 is not an ordinary, run-of-the-mill quasar, and is actually classified as a “blazar”, which are special types of very compact quasars that are associated with super massive black holes in the cores of giant elliptical galaxies. The mass of the black hole at the centre of 3C 273 has been measured at 886 million solar masses, give or take 187 million Suns or so.

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