An unexpected discovery by an international team of astronomers is forcing scientists to rethink their understanding of the environment in globular star clusters, tight-knit collections containing hundreds of thousands of stars. Two black holes in a globular star cluster. Image Credit: The University of Southampton The astronomers, including Dr Tom Maccarone from the University of [continue reading]
Observations with CSIRO’s Australia Telescope Compact Array have confirmed that astronomers have found the first known “middleweight” black hole. Galaxy ESO 243-49, about 300 million light-years away, is home to the newly found black hole. Credit: NASA, ESA and S. Farrell (University of Sydney) Outbursts of super-hot gas observed with a CSIRO radio telescope [continue reading]
Quasars are thought to be galaxies whose bright nuclei contain massive black holes around which disks are actively accreting matter. The accretion process releases vast amounts of energy, often including a wind, and as a result quasars are among the most powerful energy sources known. Because they are so bright, quasars can be seen even [continue reading]
Caption: This graph based on RXTE data provides an overview of the changing character of T5X2′s X-ray emission during outbursts from Oct. 13 to Nov. 19, 2010. As the persistent X-ray emission rises (upward steps in the plot), the burst rate increases while the burst brightness decreases. The abrupt dropout on Oct. 13 occurred when [continue reading]