taken fom http://www.discover.com

SCIENCE UPDATE: Mealtime for a Black Hole

The bizarre-looking galaxy Centaurus A is one of the noisiest radio sources in the sky. In recent years, astronomers have concluded that the Centaurus A is actually two galaxies, a spiral galaxy plunging headlong into a much larger, elliptical-shaped one. The radio commotion probably comes from a massive black hole--possibly a billion times the mass of the sun--buried in the heart of this cosmic pileup. Material disrupted by the collision falls into the black hole, growing furiously hot before vanishing forever. Centaurus A is the closest example of what astronomers call an "active galactic nucleus": the feeding ground of a giant black hole. Unfortunately, a thick band of dust from the infalling galaxy obscures the details of the action.

Now the orbiting Hubble Space Telescope has observed Centaurus A in infrared radiation, which can penetrate the gloom. A disk of hot gas, perpendicular to the dusty plane of the spiral galaxy, appears to be funnelling material toward the black hole. A much smaller disk, invisible in the Hubble picture, swirls immediately around the hole. The various disks presumably have not yet had time to align with one another. The surrounding parts of the galaxy are also in turmoil, awash with dusty filaments and bluish clusters of hot, young stars whose birth was triggered by gas clouds crashing into one another. Full results will appear in the June 1 issue of Astrophysical Journal Letters.

--Corey S. Powell Posted 5/27/98

• Active galactic nuclei, homes for Black Holes.