M87 (NGC 4486)
A giant elliptical galaxy in the Virgo
Cluster, of which it is probably the dominant member. M87 has a diameter
of at least 120,000 light-years – greater than that of the Milky Way's
disk. As M87 is nearly spherical (type E0 or E1 in Hubble's classification),
it fills a far larger volume than does our own galaxy, and thus contains
many more stars. Its mass has been estimated at 2 to 3 trillion solar masses.
A recent study by David Malin of the Anglo-Australian Observatory showed
that M87 extends further than the previously-known spherical region into
a vast elongated shape more than half a million light-years wide. Its outer
layers are noticeably distorted, probably because of gravitational interactions
with other Virgo Cluster galaxies and because of material acquired during
cannibalistic encounters.
M87 contains over 10,000 globular clusters
– including one of the largest ever seen – compared with the
Milky Way's 150 to 200. It also boasts a spectacular jet
that extends over 5,000 light-years from the center and consists of a string
of knots and clouds of gas ejected from the core. A second, less-conspicuous
jet points in the opposite direction. Images of the violent active nucleus
of M87, taken with the Hubble Space Telescope, have revealed a central object
of about 2 to 3 billion solar masses concentrated within a spherical region
just 60 light-years across and surrounded by a rapidly rotating gaseous
accretion disk. Almost certainly at the
very heart of this object is a supermassive
black hole. M87 was identified with the strong radio source Virgo A
by Walter Baade and Rudolph Minkowski
in 1954. It is also a powerful source of X-rays,
and sits near the center of a hot, X-ray emitting cloud that extends over
vast reaches of the Virgo Cluster.
| visual magnitude |
8.6 |
| apparent size |
7' |
| distance |
60 million light-years |
| position |
R.A. 12h 31m, Dec. +12° 24' |
Related
categories
• GALAXIES
• MESSIER
CATALOGUE, ALL OBJECTS
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