Close-up of NGC 4438 Nucleus Showing Outflow Shells
False color image from Hubble Space Telescope of bubbles
of hot gas blown by jets from an active nucleus in the
peculiar galaxy NGC 4438. The bubbles form because jets
of gas, not directly visible, are probably outflowing
from an accretion disk around a supermassive black hole.
When the jets from the accretion disk, which is the
brightest source in the image, run into the galaxy's gas,
they form expanding bubbles which shine. There are 2 jets
shot out in opposite directions, and therefore 2 bubbles.
The second bubble is faint and located further from the
nucleus, and is barely visible in the image. There is
more gas on one side of the nucleus than the other, so the
collision is more violent and the bubble is much brighter
on that side. The darker bands arise from dust which blocks
much of the light from the galaxy center. This is a nearby
weak example of an active galactic nucleus, which is the
phenomenon responsible for powerful quasars and radio galaxies.
This galaxy is located in the Virgo Cluster, which is
50 million light years from earth. The bright bubble is
800 light-years in diameter.
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NGC 4438 HST Nucleus and Larger View
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NGC 4438 Sky Survey
Image of NGC 4438 from
Palomar Digital Sky Survey with
outline of HST WFPC2 superposed.
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NGC 4438 HST Full WFPC2
Image of NGC 4438 from HST WFPC2.
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