A dynamically active planetary system orbits a significant portion of the white dwarf. These stars often exhibit surface metals accreted from a disk of debris. However, the complete journey of a planetesimal from its star-grazing orbit to its final dissolution in its host star is poorly understood. In a new paper, Astrophysics Journal Letter astronomers report the discovery that stars exist that are contaminated with cold metals. WD 0816-310 It cannibalized heavy elements from a planetary body as large as the dwarf planet Vesta.
WD 0816-310 is a magnetic white dwarf star located 63 light-years away in the constellation Papis. Image credit: L. Calçada / ESO.
Dr Stefano Vanullo, an astronomer at the Armagh Observatory and Planetarium, said: 'It is common for some white dwarfs – slowly cooling embers of stars like our Sun – to cannibalize parts of planetary systems. known,” he said.
“Now we find that the star's magnetic field plays a key role in this process, causing scars on the white dwarf's surface.”
The metal signatures the researchers observed on WD 0816-310 are concentrations of metal imprinted on the white dwarf's surface.
Professor Jay Farihi of University College London said: “These metals come from fragments of a planet the size of, or possibly even larger than, Vesta, which at about 500 kilometers in diameter is the second largest asteroid in the solar system. I have proven that.”
To observe WD 0816-310, astronomers FORS2 equipment upon ESO's super large telescope (VLT).
They also relied on archival data from VLT. X shooter instrument This is to confirm the survey results.
The authors noticed that the strength of the metal detections changed as the star rotated, indicating that the metals were concentrated in specific areas on the white dwarf's surface, rather than being spread smoothly across the surface. Suggests.
They also found that these changes were synchronized with changes in the white dwarf's magnetic field, indicating that this metallic scar is located at one of its magnetic poles.
Taken together, these clues indicate that the magnetic field funneled metal into the star, creating the scar.
“Surprisingly, the material was not evenly mixed on the star's surface, as theory predicted. Instead, this scar was a concentrated patch of planetary material that guided falling debris. “We've never seen anything like this before,” said John Landstreet, a professor at Western University.
“ESO offers a unique combination of capabilities needed to observe faint objects like white dwarfs and make sensitive measurements of the star's magnetic field,” Vanullo said.
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Stefano Vanullo other. 2024. Discovery of magnetically induced metal accretion on contaminated white dwarfs. APJL 963, L22; doi: 10.3847/2041-8213/ad2619
Source: www.sci.news
