Astronomers using NASA’s Hubble Space Telescope have identified a white dwarf, WD 0525+526, formed as the result of a stellar merger. This rare discovery sheds new light on the processes of stellar evolution and the origins of supernovae.
Unlike most white dwarfs, which are formed through the “peaceful death” of a single star, WD 0525+526 emerged after the violent collision and fusion of two stars. The key evidence lies in its chemical signature — traces of carbon in its atmosphere, detectable only in the ultraviolet spectrum. In visible light, the object appeared indistinguishable from a typical white dwarf.
WD 0525+526 has a mass about 1.2 times that of the Sun and a surface temperature of roughly 21,000 Kelvin. Remarkably, its atmosphere contains 100,000 times less carbon than other similar stars. Detecting such a faint signal was possible thanks to the high sensitivity of Hubble’s Cosmic Origins Spectrograph.
The finding suggests that hidden stellar mergers may be far more common than previously believed. “We want to determine how many white dwarfs actually conceal evidence of mergers, and how this connects to the processes that trigger supernova explosions,” said Antoine Bédard of the University of Warwick.
According to researchers, this discovery provides valuable insight into stellar evolution and the mechanisms behind some of the most powerful events in the universe.
