White Dwarf star seen zooming across Milky Way after surviving partial supernova: Study

Researchers from University of Warwick caught this strange star in action, raising the possibility that stellar objects may survive a blast


                            White Dwarf star seen zooming across Milky Way after surviving partial supernova: Study
(University of Warwick/Mark Garlick)

A weird white dwarf was seen zooming across the Milky Way, catching the attention of scientists. Now they suggest that the star pulled off an escape act and survived an explosion, although a partial one, according to a new study.

White Dwarfs are the remains of dead, low-mass stars such as the Sun. Typically, a white dwarf and its companion can explode into a supernova, marking the end of their life. But researchers from the University of Warwick caught this strange star in action, raising the possibility that stellar objects may survive a blast.

They speculate that the supernova pushed the white dwarf and its companion star out of their orbits, sending them in opposite directions. One of them caught the attention of scientists. They now think that different types of white dwarfs survive supernovae under different conditions. "There is clearly a whole zoo out there. Studying the survivors of supernovae in our Milky Way will help us understand the myriads of supernovae that we see going off in other galaxies," Lead author Dr Boris Gaensicke said.

The white dwarf in question is named SDSS J1240+6710. It was discovered in 2015. Gaensicke and his colleagues tried to reconstruct the White Dwarf's past by studying the composition of its atmosphere, mass and velocity. So they turned to the Hubble Space Telescope for help. The results showed that White Dwarf was weird. It did not have hydrogen or helium. Instead, it contained an unusual concoction of oxygen, neon, magnesium and silicon. The star also possessed elements such as carbon, sodium and aluminum, suggesting it went through a supernova.

(Getty Images)

The researchers then looked for another sign of a supernova explosion: heavy elements such as iron, nickel, chromium and manganese. But found nothing, suggesting that the white dwarf went through a partial explosion because it used up all of its nuclear fuel reserves, which are essential for creating these heavy elements. The White Dwarf had a 40% lower mass than the Sun and was speeding through the galaxy at 900,000 kilometers per hour. Both the observations support the idea that the star lost matter, thanks to the partial supernova.

"The star is unique because it has all the key features of a white dwarf but differs from others due to its high velocity and low mass. A partial supernova can explain the strange event. It would have been a type of supernova, but of a kind that we haven't seen before," Gaensicke added.

Professor SO Kepler of Universidade Federal do the Rio Grande do Sul, Brazil, and who originally discovered this star, said: "The fact that such a low mass white dwarf went through carbon burning is a testimony of the effects of interacting binary evolution and its effect on the chemical evolution of the Universe."

Dr Roberto Raddi of Universitat Politècnica de Catalunya, Spain, said: "Once again, the synergy between very precise Gaia astrometry and spectroscopic analysis have helped to constrain the striking properties of a unique white dwarf, which probably formed in a thermonuclear supernova and was ejected at high velocity as a consequence of the explosion."

The study is published in Monthly Notices of the Royal Astronomical Society.

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