Wednesday, September 23, 2009

Our galaxy has an expiration date

Larry Niven's short story "At the Core" speculated that our galaxy might be exploding in a chain-reaction of supernovae in or near the crowded galactic core.

AFAWK, Niven had it backwards. The galaxy's center isn't exploding; it's falling into a supermassive black hole.

Here, the Chandra x-ray observatory gives us a picture of the culprit:(Via LGF, which says it's the bright spot at center right.)
The mosaic of 88 Chandra pointings represents a freeze-frame of the spectacle of stellar evolution, from bright young stars to black holes, in a crowded, hostile environment dominated by a central, supermassive black hole.

Permeating the region is a diffuse haze of X-ray light from gas that has been heated to millions of degrees by winds from massive young stars - which appear to form more frequently here than elsewhere in the Galaxy - explosions of dying stars, and outflows powered by the supermassive black hole - known as Sagittarius A* (Sgr A*). Data from Chandra and other X-ray telescopes suggest that giant X-ray flares from this black hole occurred about 50 and about 300 years earlier.

The area around Sgr A* also contains several mysterious X-ray filaments. Some of these likely represent huge magnetic structures interacting with streams of very energetic electrons produced by rapidly spinning neutron stars or perhaps by a gigantic analog of a solar flare.
Here's a close-up of Sagittarius A*:Cf. the Wikipedia entry.

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