NGC 4889 and Its Huge Central Black Hole
The largest galaxy in the Coma cluster hides a central black hole of several billion solar masses
Even larger and more massive than NGC 4874, NGC 4889 is a supergiant elliptical galaxy located in the center of the Coma cluster, about 308 million light-years away from us.
In the Hubble image above, NGC 4889 is the central galaxy. Its massive halo, which extends obliquely to the orientation of the image, has a diameter of about 1.3 million light-years (thirteen times the diameter of the Milky Way).
Elliptical galaxies have spheroidal shapes with varying degrees of flattening. Unfortunately, we do not know how deeply NGC 4889 extends along the axis not measurable from our vantage point. This implies uncertainty in calculating the galaxy’s mass, which could vary between 8,000 and 15,000 billion solar masses. Much of this mass, as usual, is not made of stars and gas but dark matter. In any case, the total mass of NGC 4889 is far greater than that of the Milky Way. It is very likely the largest and most massive galaxy within 100 megaparsecs of our position in the local Universe.
NGC 4889 appears today as an immense collection of stars clustered towards the center, a galaxy lacking clear signs of activity. However, by studying the orbital…
