Free Astronomy Magazine July-August 2019

46 JULY-AUGUST 2019 SPACE CHRONICLES “Therefore, a detection of dust at some point in time indicates that a number of stars have already formed and died well before that point.” Using ALMA (Atacama Large Mil- limeter/submillimeter Array), Tamura by ALMAObservatory Radio emissions from dust particles in MACS0416_Y1 R esearchers have detected a ra- dio signal from abundant inter- stellar dust in MACS0416_Y1, a galaxy 13.2 billion light-years away in the constellation Eridanus. Stan- dard models can’t explain this much dust in a galaxy this young, forcing us to rethink the history of star for- mation. Researchers now think MACS0416_Y1 experienced stag- gered star formation with two in- tense starburst periods 300 million and 600 million years after the Big Bang with a quiet phase in between. Stars are the main players in the Uni- verse, but they are supported by the unseen backstage stagehands: star- dust and gas. Cosmic clouds of dust and gas are the sites of star forma- tion and masterful storytellers of the cosmic history. “Dust and relatively heavy elements such as oxygen are disseminated by the deaths of stars,” said Yoichi Tamura, an associate professor at Nagoya University and the lead au- thor of the research paper. A rtist’s impression of the distant galaxy MACS0416_Y1. Based on the observations with ALMA and HST, researchers assume that this galaxy contains stellar clusters with a mix of old and young stars. The clouds of gas and dust are illumi- nated by starlight. [National Astro- nomical Observatory of Japan]