Type

Supermassive

Location

In the constellation Leo

Distance

38 million light-years (11.6 megaparsecs)

Mass

16 million times the mass of the Sun

Size

Diameter roughly the size of the orbit of Mercury, the closest planet to the Sun

Discovery Methods

• Measuring the motions of stars

NGC 3384

At about 16 million times the mass of the Sun, the black hole at the center of NGC 3384 is relatively small -- only about four times the mass of the black hole at the center of the Milky Way. Also like the Milky Way, NGC 3384's black hole is quiet. It produces little radio energy, suggesting that its surrounding accretion disk of hot gas is thin.

The galaxy itself (which may also have been mistakenly cataloged under a second name, NGC 3371) is a member of a small group of galaxies known as Leo I, which is about 40 million light-years away. NGC 3384 is classified as a lenticular galaxy, which means it is shaped like a lens, with a bulge in the center tapering evenly toward the edges. A "bar" of stars crosses the center of the galaxy, with the supermassive black hole inside this bar. The bar helps funnel gas and dust into the galaxy's central regions.

Astronomers have studied NGC 3384 to learn not just about the black hole, but about the relationship between the black hole and a possible "halo" of dark matter around the galaxy, and about the relationship between the black hole's mass and the mass of the surrounding clump of stars. The studies indicate that the central clump is a "pseudobulge," built by the funneling action of the bar and not by the processes that gave birth to the galaxy.

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This document was last modified: March 14, 2012.