Researchers observe exploding White Dwarf for the first time

For the first time, a team of researchers has been able to observe an exploding White Dwarf - the dense leftover of a Sun-like star. The findings reveal that the white dwarf is around the mass of the Sun and the explosion generated a fireball with a temperature of around 327k degrees, making it around sixty times hotter than the Sun.

Sometimes these dead stars flare back to life in a super-hot explosion and produce a fireball of X-ray radiation. Using the eROSITA X-ray telescope, the researchers from Tübingen University and led by Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) were able to observe such an explosion of X-ray light for the very first time.

"These X-ray flashes last only a few hours and are almost impossible to predict, but the observational instrument must be pointed directly at the explosion at exactly the right time," said Ole König from the Astronomical Institute at FAU in the Dr Karl Remeis observatory in Bamberg.

On July 7, 2020 the Earth-based X-ray observatory measured strong X-ray radiation in an area of the sky that had been completely inconspicuous four hours previously. When the telescope surveyed the same position in the sky four hours later, the radiation had disappeared. According to the researchers, the X-ray flash that had previously completely overexposed the center of the detector must have lasted less than eight hours.

"Not only the short duration of a flash is a challenge, but also the fact that the spectrum of emitted X-rays is very soft. Soft X-rays are not very energetic and easily absorbed by interstellar medium, so we cannot see very far in this band, which limits the number of observable objects, be it a nova or ordinary star. Telescopes are normally designed to be most effective in harder X-rays where absorption is less important, and that's exactly the reason why they would miss an event like this," concludes Dr Victor Doroshenko from Tübingen University.

X-ray explosions like this have been observed directly for the first time. Previously, they were predicted by theoretical research.

König, Prof. Dr. Jörn Wilms and a research team from the Max Planck Institute for Extraterrestrial Physics, the University of Tübingen, the Universitat Politécnica de Catalunya in Barcelona und the Leibniz Institute for Astrophysics Potsdam, have published an article about this observation in the journal Nature.