Dynamically active planetary systems orbit a substantial portion of white dwarf stars. These stars typically show surface area metals accreted from particles disks. The complete journey of a planetesimal from star-grazing orbit to last dissolution in the host star is inadequately comprehended. In a brand-new paper in the Astrophysical Journal Lettersastronomers report the discovery that the cool metal-polluted star WD 0816-310 has actually cannibalized heavy aspects from a planetary body comparable in size to the dwarf world Vesta.
An artist’s impression of WD 0816-310, a magnetic white dwarf situated 63 light-years away in the constellation of Puppis. Image credit: L. Calçada/ ESO.
“It is popular that some white overshadows– gradually cooling cinders of stars like our Sun– are cannibalizing pieces of their planetary systems,” stated Dr. Stefano Bagnulo, an astronomer at Armagh Observatory and Planetarium.
“Now we have actually found that the star’s electromagnetic field plays an essential function in this procedure, leading to a scar on the white dwarf’s surface area.”
The metal scar the group observed on WD 0816-310 is a concentration of metals inscribed on the white dwarf’s surface area.
“We have actually shown that these metals stem from a planetary piece as big as or perhaps bigger than Vesta, which has to do with 500 km throughout and the second-largest asteroid in the Solar System,” stated University College London’s Professor Jay Farihi.
To observe WD 0816-310, the astronomers utilized the FORS2 instrument on ESO’s Very Large Telescope (VLT).
They likewise depend on archival information from VLT’s X-shooter instrument to verify their findings.
The authors saw that the strength of the metal detection altered as the star turned, recommending that the metals are focused on a particular location on the white dwarf’s surface area, instead of efficiently spread out throughout it.
They likewise discovered that these modifications were integrated with modifications in the white dwarf’s electromagnetic field, suggesting that this metal scar lies on among its magnetic poles.
Created, these ideas show that the electromagnetic field funneled metals onto the star, developing the scar.
“Surprisingly, the product was not equally blended over the surface area of the star, as forecasted by theory. Rather, this scar is a focused spot of planetary product, kept in location by the exact same electromagnetic field that has actually assisted the infalling pieces. Absolutely nothing like this has actually been seen before,” stated Western University’s Professor John Landstreet.
“ESO has the special mix of abilities required to observe faint items such as white overshadows, and sensitively determine excellent electromagnetic fields,” Dr. Bagnulo stated.
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Stefano Bagnulo et al2024. Discovery of Magnetically Guided Metal Accretion onto a Polluted White Dwarf. ApJL 963, L22; doi: 10.3847/ 2041-8213/ ad2619
