Sagittarius A* at the Center of Our Galaxy

A black hole called Sagittarius A* (pronounced A-star) lies at the center of our Milky Way Galaxy, only 27,000 light-years away. Its mass is roughly 4 million times the mass of the Sun. Our galaxy’s black hole is mild-mannered compared to the central black holes in some other galaxies, much more calmly consuming material around it. However, it does sometimes flare-up. An flareup lasting several hours is documented in this series of X-ray images from the orbiting Nuclear Spectroscopic Telescope Array (NuSTAR). NuSTAR is the first instrument to provide focused views of the area surrounding Sgr A* at X-ray energies higher than those accessible to the Chandra and XMM observatories. The flare sequence is shown in the panels on the right. The images cover a two-day span. X-rays are generated in material heated to over 100 million C and traveling at nearly the speed of light as it falls into the black hole. The center X-ray image spans about 100 light-years. Its bright white region is the hottest material closest to the black hole; the pinkish cloud probably belongs to the remnant of a nearby supernova. Click the picture to embiggen it.

Sgr A* is monitored on a daily basis by the X-ray telescope of the Swift satellite. I made contributions to the design of the power and thermal control systems of the Burst Alert Telescope instrument on Swift.

Image Credit: NASA

Looking at the Galactic Core

galactic coreHere are the views seen by four different observatories looking in toward the galactic core. At the very center, a cluster with a half-million-or-so stars surrounds the Milky Way’s central supermassive black hole, which is about 4 million times the mass of our sun. The galaxy’s nucleus (marked) is home to the central, supermassive black hole called Sagittarius A*.

Image Credits: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) Acknowledgment: T. Do, A.Ghez (UCLA),V. Bajaj (STScI)