Wear your scars, they said. So this 'cannibal' dead star took it quite literally

A very strange white dwarf star has been discovered by astronomers with a metallic scar on its surface which is possiblya remnant of the unfortunate planet which was eaten by the killer star.

The white dwarf, which is known as WD 0816-310, is a superdense husk of a dead star that is located 63 light-years from Earth.

Earlier, astronomers believed that the fragments of asteroids or planets, which are shredded and consumed by white dwarfs, eventually get spread evenly across the star's surfaces.

However, in the new study which was published in The Astrophysical Journal Letters, the researchers observed the Earth-size embers of the dead star and found that the leftovers from one of the eaten planets got locked inplace with the help of powerful magnetic fields and created a dark metallic streak across the star's surface, which appears like a scar.

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"It is well known that some white dwarfs — slowly cooling embers of stars like our Sun — are cannibalising pieces of their planetary systems," said lead author Stefano Bagnulo, an astronomer at Armagh Observatory and Planetarium in Northern Ireland, in a statement.

Why the scar though?

"Now we have discovered that the star's magnetic field plays a key role in this process, resulting in a scar on the white dwarf's surface," he added.

White dwarfs are formed when fuel gets depleted from stars, ranging between one-tenth and eight times the mass of the sun, and no nuclear fusion is carried out.

When this occurs, the star's outer layer is removed and a compact, dense, white-hot core is revealed which slowly cools over time.

As per a study published in the journal Publications of the Astronomical Society of the Pacific in 2001, nearly 97 per cent of the stars in the Milky Way, which include the sun, are destined to become white dwarfs.

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However, the compositions and capabilities of these ultradense balls have remained mysterious in different ways.

Scientists observed that the zombie star rotated on its axis and the metals also matched up with changes in the magnetic field of the white dwarf.

The observations helped scientists understand that the polar magnetic field of WD 0816-310 had "funnelled" the metallic leftovers of one of its meals onto one of the magnetic poles of the dwarf star, which created a scar.

"This scar is a concentrated patch of planetary material, held in place by the same magnetic field that has guided the infalling fragments," said co-author John Landstreet, a professor emeritus at the University of Western Ontario and a visiting professor at the Armagh Observatory and Planetarium, in the statement. "Nothing like this has been seen before," he added.

(With inputs from agencies)