London, UK – Astronomers have made a groundbreaking discovery of a white dwarf star with a dark metallic “scar” on its surface, believed to be the result of a planetary fragment being pulled too close to its host. The star, known as WD 0816-310, is located about 63 light years away and is reminiscent of our sun in its earlier days, now reduced to a dense, Earth-sized remnant. Recent observations unveiled a concentrated patch of metals on its surface, indicating the remnants of a swallowed piece of planet or asteroid.
Researchers, led by astronomer Stefano Bagnulo from Armagh observatory in Northern Ireland, UK, found that the planetary material seemed to be trapped in place by the star’s magnetic field, creating a distinct surface structure. This metallic scar covers a significant portion of the star’s pole, larger than the equivalent of Antarctica on Earth. White dwarfs are the remnants left behind after a dying star sheds its outer layers to form a planetary nebula, with their dense gravitational pull capable of tearing apart planets or asteroids that come too close.
Professor Jay Farihi from University College London, a co-author of the study, explained that when a planet or asteroid approaches a white dwarf, it gets torn apart in a tidal spiral, leading to its ultimate demise. The metals detected on the star suggest they may have originated from a planetary fragment as large as Vesta, the second-largest asteroid in our solar system, approximately 500km across.
Interestingly, the team observed changes in metal detection as the star rotated, indicating that the metals are concentrated in a specific area on the white dwarf’s surface rather than being evenly spread. These fluctuations were found to be linked to changes in the white dwarf’s magnetic field, suggesting that the metallic scar is located on one of its magnetic poles.
Further analysis by Professor John Landstreet from the University of Western Ontario and the Armagh observatory revealed that this scar is a concentrated patch of planetary material held in place by the star’s magnetic field. These findings provide new insights into the study of polluted white dwarfs, offering valuable information about the composition of exoplanets.
The discovery of this unique phenomenon was published in the Astrophysical Journal Letters, marking a significant advancement in understanding the interaction between white dwarfs and planetary fragments. The magnetic field of the white dwarf star appears to play a crucial role in shaping the surface and retaining planetary material, shedding light on the mysterious mechanisms at play in our universe. Through continued research and observation, astronomers hope to uncover more secrets of these cosmic interactions and their implications for the formation and evolution of celestial bodies.