Elliptical Galaxy M-87 in Virgo - With Jet & Companion Galaxies

This is a CCD image taken with an STL-1301E CCD camera thru Kopernik's 20 inch F/8.1 telescope.

Charles Messier: (March 18th, 1781) 'Nebula without star in Virgo….. This nebula appears to have the same light as the two nebulae M-84 and M-86.'

John Herschel: (1864) 'Very bright, pretty large, round, very suddenly brighter in the middle where there is a nucleus.'

M-87 (NGC 4486) is a Giant Elliptical Galaxy, probably the largest member of the Virgo Galaxy Cluster and is about 50 million light-years away. It was discovered by Charles Messier in March 1781. This is undoubtedly one of the most massive and luminous of all known galaxies, with at least a trillion stars. It is something like three times larger than a typical large galaxy. Many galaxy clusters have a centrally located "Cluster Dominant Elliptical Galaxy" of massive proportions. M87 is remarkable for its large family of globular star clusters which appear as many small fuzzy images scattered throughout the outer parts of the galaxy. There are thousands of such clusters in M-87. The galaxy is also accompanied by a group of smaller elliptical galaxies and has a strange jet feature discussed below.

The M-87 "jet":

M-87 is a strong source of radio emission, originally detected by J.G.Bolton in 1948, and now called "Virgo A". The strong radio energy is associated with a curious optical feature first mentioned in astronomical literature by H.D.Curtis at the Lick Observatory in 1918: "….. A curious straight ray lies in a gap in the nebulosity.... apparently connected with the nucleus by a thin line of matter...". This energetic jet stretches outward for 5,000 light-years. It has been detected across the spectrum, from x-ray to optical to radio wavelengths. The observed emission is likely created as high energy electrons spiral along magnetic field lines, so called synchrotron radiation. But ultimately, the jet is thought to be produced as matter near the center of M-87 swirls toward a spinning, super-massive black hole. Strong electromagnetic forces are generated and eject material away from the black hole along the axis of rotation in a narrow jet.

The other galaxies in the M-87 area:

M-87 is accompanied by a group of much smaller Elliptical Galaxies, some of which appear in the Kopernik image above. All appear at first to be typical elliptical galaxies, but astronomers note that most seem to be stripped of their outer stars and are more the cores of true galaxies. It seems that M-87 has added to its mass by stripping the outer parts of theses galaxies and many others. At some point they may well be completely cannibalized by M-87.

Links to Hubble & Chandra Space Telescopes images of the M-87 "jet":

Chandra Sheds Light on the Knotty Problem of the M87 Jet: (link)

Hubble Witnesses Spectacular Flaring in Gas Jet from M87's Black Hole: (link)

More info on the optical jet of M87: (link).

George Normandin, KAS

May 20th, 2009