Thanks to an in-depth look into the composition of gas in the Perseus galaxy cluster, Japan’s Hitomi mission has given scientists new insights into the stellar explosions that formed its chemical elements.
Before its brief mission ended unexpectedly in March 2016, Japan’s Hitomi X-ray observatory captured exceptional information about the motions of hot gas in the Perseus galaxy cluster. Now, thanks to unprecedented detail provided by an instrument developed jointly by NASA and the Japan Aerospace Exploration Agency (JAXA), scientists have been able to analyze more deeply the chemical make-up of this gas, providing new insights into the stellar explosions that formed most of these elements and cast them into space.
The Perseus cluster, located 240 million light-years away in its namesake constellation, is the brightest galaxy cluster in X-rays and among the most massive near Earth. It contains thousands of galaxies orbiting within a thin hot gas, all bound together by gravity. The gas averages 90 million degrees Fahrenheit (50 million degrees Celsius) and is the source of the cluster’s X-ray emission.
Using Hitomi’s high-resolution Soft X-ray Spectrometer (SXS) instrument, researchers observed the cluster between Feb. 25 and March 6, 2016, acquiring a total exposure of nearly 3.4 days. The SXS observed an unprecedented spectrum, revealing a landscape of X-ray peaks emitted from various chemical elements with a resolution some 30 times better than previously seen.
In a paper published online in the journal Nature on Nov. 13, the science team shows that the proportions of elements found in the cluster are nearly identical to what astronomers see in the Sun.
“There was no reason to expect that initially,”…