nov 062012
The Milky Way's Black Hole is Suddenly Eating a Lot More

  As black holes go, Sagittarius A* is relatively low-key. The supermassive black hole at the center of our galaxy emits very little energy for its size, giving off roughly as much energy as the Sun, even though it is 4 billion times as massive. This false-color image shows the central region of our Milky [continue reading]

okt 082012
Twists and Turns in Interacting Galaxies

  Almost thirty years ago the Infrared Astronomy Satellite, IRAS, discovered that the Universe contained many fabulously luminous galaxies, some of them more than a thousand times brighter than our own galaxy, but which are practically invisible at optical wavelengths. The reason for their optical dimness is that their bright light comes not from stars, [continue reading]

aug 242012
Type Ia Supernovae Have Different Origins

  Exploding stars called Type 1a supernovae are ideal for measuring cosmic distances because they are bright enough to spot across the Universe and have relatively the same luminosity everywhere. Although astronomers have many theories about the kinds of star systems involved in these explosions (or progenitor systems), no one has ever directly observed one—until [continue reading]