Forming Stars in the Stream

by | Apr 14, 2014 | Daily Paper Summaries

Orbiting our galaxy are many smaller dwarf galaxies. As they orbit, some of these galaxies produce vast streams of gas that stretch around our Milky Way galaxy. Much of this gas still has the potential for forming stars. This astrobite will summarize a recent discovery of one of these stars.

What Fed Sgr A* its Latest Meal?

What Fed Sgr A* its Latest Meal?

by | Jan 20, 2014 | Daily Paper Summaries

The black hole at the center of our galaxy, Sgr A*, is a very picky eater. However, with the discovery of the G2 cloud, astronomers have had the opportunity to watch the infrequent feeding process in Sgr A* in action. While the origin of this cloud is still debated, research is beginning to suggest that G2 is a gas cloud that was ripped away from a giant star in orbit around our galaxy’s central black hole.

Galactic Archaeology through Stars

Galactic Archaeology through Stars

by | Dec 20, 2013 | Daily Paper Summaries

How the various structures within our own Milky Way galaxy evolved is still an open question that astronomers have been slowly piecing together for a very long time. These galactic archaeologists are beginning to test a previously proposed method known as “chemical tagging” to fingerprint stars in our galaxy and trace their origin.

Where do hypervelocity stars come from?

Where do hypervelocity stars come from?

by | May 24, 2013 | Daily Paper Summaries

TITLE: Supernovae in the Central Parsec: A Mechanism for Producing Spatially Anisotropic Hypervelocity StarsAUTHORS: Kastytis Zubovas, Graham A. Wynn, Alessia GualandrisAUTHORS’ INSTITUTION: Theoretical Astrophysics Group, University of Leicester Hypervelocity Stars In 2005, Brown et al. discovered a star with a radial velocity of ~700 km/s, which is more than 3 times the Solar velocity! This star is moving so quickly that its velocity is high enough to escape the Milky Way. The existence of such stars, deemed hypervelocity stars (HVSs), was predicted almost 20 years earlier by Hills (1988). The so-called Hills mechanism ejects stars at high speeds from the center of the Galaxy after a binary stellar system gravitationally interacts with the supermassive black hole at the center of the Galaxy. In such a three-body interaction, one star can be ejected at very high speeds while the other remains in the central region of the Galaxy on a highly eccentric orbit. A number of highly eccentric short-period stars are observed in the Galactic center, which suggests associated HVSs may exist. Since the initial discovery of an HVS in 2005, many more have been discovered (see this astrobite). A small warning: the exact definition of HVSs can vary throughout the literature. In this post, stars traveling away from the Galactic center with velocities high enough to have become unbound from the central black hole are referred to as HVSs.While it is very likely that the Hills Mechanism does create HVSs, it is unclear whether all HVSs are created via this method. Curious if there is a supplemental method to produce HVSs, the authors of today’s paper examine the production...