In the constellation Cetus
65 million times the mass of the Sun
Diameter larger than Earth's orbit around the Sun
One way to discover a supermassive black hole and to measure its mass is to look for hot water. Disks of gas and dust around black holes can contain water molecules. Energy from nearby stars, or from the disk itself, can boost the energy level of the water molecules, causing them to emit beams of microwaves known as masers. If Earth lies along such a beam's path, radio telescopes sensitive to microwaves can detect them.
Precise tracking of such a maser reveals its motion around the center of the galaxy. By applying the laws of orbital motion, astronomers can determine the precise mass of the central object. If the object is massive enough and confined to a small enough volume, it can only be a black hole.
Using measurements made from 2005 to 2009, a team of astronomers measured the masses of the supermassive black holes in seven galaxies, including the spiral galaxy NGC 1194.
The measurements show that the black hole is about 65 million times as massive as the Sun. That is fairly puny in relation to the big "bulge" of stars around it, suggesting that the black hole was starved in its infancy.
Supermassive black holes in young galaxies pull in gas and dust. As this material squeezes in around the black hole it forms new stars. The newborn stars and the hot accretion disk around the black hole create energy that sweeps away the remaining gas and dust from the galaxy's center, shutting down the process of starbirth.
Astronomers have discovered a strong correlation between the mass of a supermassive black hole and the mass of the stars around it, but the black hole in NGC 1194 is well below the mass required to achieve the proper correlation. One possible explanation is that not enough material funneled toward the black hole when it was young, so its growth was stunted.
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This document was last modified: March 15, 2012.