An international team of astronomers has announced in the journal Nature the discovery of a star with one half of its surface covered by hydrogen and the other by helium. Dr Przemysław Mróz of the Warsaw University (UW) Astronomical Observatory is co-author of the publication.
The object was discovered in data from the Zwicky Transient Facility (ZTF) sky survey carried out at Palomar Observatory in California. Dr Przemysław Mróz of the UW’s Astronomical Observatory, among others, was responsible for measuring the brightness of more than one billion stars observed by the ZTF project, thanks to which this unusual object was found. It was named Janus, after the Roman god of all origins, who was depicted as a two-faced deity.
The star was distinguished by large changes in brightness, repeating every 15 minutes. “This is as long as one rotation of the star around its axis”, says Dr Frost.
Additional observations made with the Keck Telescope, located at the Mauna Kea Observatory in Hawaii, revealed the dual nature of the star.
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