Satellite's swan song: 'serenity' in Perseus cluster gas


Just before its untimely destruction, Japan's Hitomi satellite inspected the hot gas cloud within the Perseus cluster and found it surprisingly quiet – on cosmological scales, that is.


Japan Aerospace Exploration Agency's Hitomi satellite, launched in February, lasted but five weeks before breaking apart. But prior to its demise, it managed to peer into the Perseus cluster, an assemblage of thousands of galaxies bound together by gravity and containing a vast amount of extremely hot gas averaging around 50 million °C.

Instead of a turbulent whirl, the Soft X-Ray Spectrometer on the craft saw the gas was relatively still: moving only around 590,000 kilometres per hour. While it sounds incredibly fast for us on Earth, it's surprisingly modest on cosmological scales.

Prior to Hitomi's launch, astronomers were unable to measure the gas' detailed dynamics – particularly its relationship to bubbles of gas expelled by an active supermassive black hole in the cluster's core galaxy, NGC 1275.

"Although this gas is continually stirred by fast outflows from the central black hole, its velocities are small on astronomical scales and show evidence for only minor levels of turbulence," says Richard Kelley, the US principal investigator for the Hitomi collaboration.

The work was published in Nature. You can learn more about the mission and observations in the video below.

  1. http://www.nature.com/nature/journal/v535/n7610/full/nature18627.html
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