Free Astronomy Magazine May-June 2016

SPACE CHRONICLES to build the foundations of galaxy evolution studies by predicting the star-formation rate of distant gal- axies from the light they emit. To understand the physics of the for- mation and evolution of galaxies it is crucial to know at what rate gal- axies form stars, referred to as the star-formation rate. This rate shows how active a galaxy is: young gal- axies with large amounts of gas form many stars, while red and old galaxies that have depleted their gas reservoirs do not actively form stars. Cosmological events such as mergers between galaxies can also boost the star-formation rate. However, unless we are observing the Milky Way and very close local galaxies, we cannot detect individual stars and star-form- ing regions in distant galaxies. Therefore, we need to rely on global observable characteristics to esti- mate the star-formation rate of gal- axies located far away. The best way to fully understand the properties of galaxies is by studying them at a broad range of wave- lengths; as each type of light is emit- ted from a different actor in a gal- axy. For example, the ultraviolet light comes from the youngest and most massive stars, while the optical and near-infrared continuum light is emitted mostly from more evolved stars. Infrared light, on the other hand, traces dust in a galaxy, and emission lines that are detected in spectral lines trace the gas clouds. The group of researchers, led by Irene Shivaei, observed 17 bright distant galaxies with the MOSFIRE high-resolution near-infrared spec- trometer. Then, they combined the spectra with infrared images of the Spitzer Space Telescope, the Her- schel Space Observatory, and optical images of the Hubble Space Tele- scope, to create a complete multi- UCR student traces star formation rates in distant galaxies A group of researchers, led by a University of California, Riverside graduate student, observed distant galaxies with the MOSFIRE high-resolution near-infra- red spectrometer at W. M. Keck Ob- servatory and their results will help by Keck Observatory A n image of distant galaxies forming stars. [NASA, ESA and Bahram Mobasher]