... arXiv.org . astro-ph . ... We fit the near-infrared to radio spectral energy distributions of 30 luminous and ultra-luminous infrared galaxies with pure starburst models or models that include both starburst and AGN components to determine important physical parameters for this population of objects. In particular we constrain the optical depth towards the luminosity source, the star formation rate, the star formation efficiency and the AGN fraction. ...

... Bad Astronomy . ... Bitesize Astronomy . ... The last step encompassed them all with galaxies , and how we discovered that the Milky Way was not the entire Universe. ... And just like those star clusters, there are different kinds of galaxy clusters. ... There are vast clusters of clusters, called superclusters, which contains hundreds of thousands or even millions of galaxies. ... Our own Galaxy has 400 billion stars in it, yet there are clusters out there with millions of galaxies like our own. ...

... Compact Binaries . ... Unlike the Sun, most stars in our Galaxy orbit another star: these systems are called binary stars. Generally it takes many years for the two stars to orbit around each other. ... These binaries are interesting for many reasons. One is that they are predicted to emit lots of gravitational waves. ... Over time as gravitational waves are emitted, the time taken for the two stars to orbit one another changes by a small but measurable amount. ...