Astronomers have caught the explosion of a red supergiant star in its earliest stages yet. The light from supernova SN 2013fs reached the Earth on October 6, 2013 from the galaxy NGC 7610 which is 150 million light-years away. The discovery, by a robotic telescope (iPTF) in California which specializes in finding young supernovae, was made only three hours after the explosion. Three hours later, the world’s largest telescope (Keck in Hawaii) made a detailed study of the supernova. These record-breakingly-early observations reveal new information about what happens to a massive star during its final stages of life. The data clearly show the signs of the supernova interacting with material blown out from the star in the year before the explosion. When the researchers looked again, 12 hours later, with the Nordic Optical Telescope on La Palma, the signal had already faded. This shows how important speed is when it comes to these observations. The observed supernova belongs to the most common kind of supernovae which are produced when red supergiant stars are no longer able to support themselves against gravity.
The OKC is part of the Zwicky Transient Facility collaboration which will start taking data this year and will systematically search for new transients in the sky. This should lead to the discovery of many more supernovae in their earliest stages.
The article which discusses this discovery was published in the journal Nature Physics (see also the News and Views). The first author is Ofer Yaron from the Weizmann Institute in Israel and co-authors from the OKC are Jesper Sollerman, Claes Fransson, and Francesco Taddia.