June 5, 2000
Photo No: H2000-21a
Feasting Black Hole Blows Bubbles
A monstrous black hole's rude table manners include blowing huge bubbles
of hot gas into space. At least, that's the gustatory practice followed
by the supermassive black hole residing in the hub of the nearby galaxy
NGC 4438. Known as a peculiar galaxy because of its unusual shape, NGC
4438 is in the Virgo Cluster, 50 million light-years from Earth.
These NASA Hubble Space Telescope images of the galaxy's central region
clearly show one of the bubbles rising from a dark band of dust. The
other bubble, emanating from below the dust band, is barely visible,
appearing as dim red blobs in the close-up picture of the galaxy's hub
(the colorful picture at right). The background image represents a wider
view of the galaxy, with the central region defined by the white box.
These extremely hot bubbles are caused by the black hole's voracious
eating habits. The eating machine is engorging itself with a banquet of
material swirling around it in an accretion disk (the white region below
the bright bubble). Some of this material is spewed from the disk in
opposite directions. Acting like high-powered garden hoses, these twin
jets of matter sweep out material in their paths. The jets eventually
slam into a wall of dense, slow-moving gas, which is traveling at less
than 223,000 mph (360,000 kph). The collision produces the glowing
material. The bubbles will continue to expand and will eventually
dissipate. Compared with the life of the galaxy, this bubble-blowing
phase is a short-lived event.
The bubble is much brighter on one side of the galaxy's center because
the jet smashed into a denser amount of gas. The brighter bubble is 800
light-years tall and 800 light-years across.
The observations are being presented June 5 at the American Astronomical
Society meeting in Rochester, N.Y. Both pictures were taken March 24,
1999 with the Wide Field and Planetary Camera 2. False colors were used
to enhance the details of the bubbles. The red regions in the picture
denote the hot gas.
Credits: NASA and Jeffrey Kenney and Elizabeth Yale (Yale University)