Astronomers using the NASA/ESA Hubble Space Telescope have made a groundbreaking discovery, uncovering an ultra-massive white dwarf that formed when two stars collided. This rare finding challenges previous assumptions about the origins of these celestial objects and suggests that they may be more common than initially thought.
White dwarfs are the remnants of stars that exhaust their hydrogen fuel, leaving behind dense, hot cores composed mainly of carbon and oxygen or oxygen and neon. These objects can have masses up to 1.4 times that of the Sun, but ultra-massive white dwarfs with masses over the Sun’s mass are rare.
The Hubble Space Telescope detected unusual carbon signatures in the atmosphere of a white dwarf called WD 0525+526, which is located just 128 light-years away. The team used Hubble’s Cosmic Origins Spectrograph to investigate this object and found that it has an atmosphere composed mostly of hydrogen and helium, unlike typical white dwarfs.
This discovery indicates that WD 0525+526 may have formed through a violent collision between two white dwarfs or a white dwarf and a subgiant star. The team’s findings suggest that other seemingly normal white dwarfs could be the result of cosmic collisions, raising new questions about their origins.
The researchers hope to explore how common these carbon-rich white dwarfs are and how many stellar mergers might be hiding among them. This study provides important insights into the formation history of white dwarf binaries and the pathways to supernova explosions.
The Hubble Space Telescope has provided unique ultraviolet observations that allowed the team to detect the carbon in WD 0525+526’s atmosphere, which was not visible in visible light. The discovery highlights the importance of this instrument in uncovering rare celestial objects and challenging our understanding of the universe.
Source: https://esahubble.org/news/heic2510