ASTROPHYSICS: Twinkle, Twinkle, Big Black Hole

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Science  27 Feb 2004:
Vol. 303, Issue 5662, pp. 1261a
DOI: 10.1126/science.303.5662.1261a

A supermassive black hole about 4 million times the mass of the Sun, Sagitarrius A-star (Sgr A*), is thought to lie at the center of the Milky Way.

In support of this, Ghez et al. measured a variable infrared emission that comes from a region within 5 astronomical units of Sgr A*. No other emissions show such extreme variability in flux density, and the infrared flares are persistent. If all of the emissions come from the same source, then gravitational lensing, accretion disk illumination, and star disk collisions can be eliminated as possible causes of the infrared flares. The flares probably come from plasma that is either accreting or flowing out from the edges of the black hole. Additional observations of these persistent flares should provide a better picture of black hole energetics. — LR

Astrophys. J. 601, L159 (2004).

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