Credit: NASA/SAO/CXC/C.Jones et al.

An Elliptical Galaxy's "Inner Spiral"

Galaxies come in two types: spiral galaxies, shaped like giant, flattened whirlpools, and ellipticals, which are shaped like giant (though rather nondescript) ellipsoids. The connection between these two kinds of shapes is not well established. However, a recent observation of the elliptical galaxy NGC 4636 by the Chandra X-ray Observatory provides important new information. The Chandra image (shown above) provided a surprise to astronomers, since it shows 2 previously unseen spiral arms of extremely hot gas (at a temperature of about 10 million degrees) emanating from the center of this elliptical galaxy. The arms themselves are embedded in a spherical cloud of hot gas, though this hot cloud is cooler than the spiral arms. Astronomers believe that these arms are the leading edge of a galaxy-sized shock wave (with an energy equivalent to that of a few thousand supernovae), possibly related to a "feeding cycle" of a massive black hole at the galaxy's center.

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Page Author: Dr. Michael F. Corcoran
Last modified January 6, 2002