Free Astronomy Magazine July-August 2015

SPACE CHRONICLES very rapidly, about 80 times faster than our galaxy today. Only a handful of galaxies currently have accurate distances measured in this epoch of the Universe and none younger than this. “Every confirmation adds another piece to the puzzle of how the first gener- ations of galaxies formed in the early universe,” said Pieter van Dok- Astronomers set a new galaxy distance record by Keck Observatory A n international team of as- tronomers, led by Yale and the University of California, Santa Cruz, pushed back the cosmic frontier of galaxy exploration to a time when the Universe was only five percent of its present age. The team discovered an exceptionally luminous galaxy more than 13 bil- lion years in the past and determin- ed its exact distance from Earth using the powerful MOSFIRE instru- ment on the 10-meter Keck I tele- scope at the W. M. Keck Observa- tory in Hawaii. These observations confirmed it to be the most distant galaxy ever measured, setting a new record. The galaxy, EGS-zs8-1, is one of the brightest and most massive objects in the early uni- verse and was originally identified based on its particular colors in im- ages from NASA’s Hubble and Spit- zer Space Telescopes. “While we saw the galaxy as it was 13 billion years ago, it had already built more than 15 percent of the mass of our own Milky Way today,” said Pascal Oesch of the Yale Uni- versity, the lead author of the study. “But it had only 670 million years to do so. The universe was still very young then.” The new dis- tance measurement also enabled the astronomers to determine that EGS-zs8-1 was still forming stars F ield of galaxies in the CANDELS survey (Cosmic Assembly Near-infra- red Deep Extragalactic Legacy Survey). [NASA, ESA, P. Oesch and I. Momcheva (Yale University), and the 3D-HST and HUDF09/XDF Teams]