White dwarf rips a planet

A small planet was torn into pieces and disappeared after moving too close to a white dwarf. The ill-fated planet may have been pulled towards the white dwarf by the gravity of one or more unseen planets, astronomers said.

Stars like the Sun (mostly hydrogen and helium) will bulge into a giant red glowing sphere - called red giants - as they age. After that, the upper layers of their material will gradually separate, leaving only the core. Then they are called white dwarfs.

Astronomers are very interested in finding signs of planets around these dying stars, because they will help them understand what happens to solar-like planets. our.

Previously, scientists had seen disks of dust flying around many white dwarfs. It has also been discovered that, on the surface of a pluripotent white dwarf - a sign that they may have " swallowed up " small planets that fly too close after tearing down " less fortunate bodies. " luckily "this.

Now, researchers at the University of Warwick (UK) have had the most compelling evidence of a white dwarf devouring a planet. They saw the formation of a metal dust ring around a white dwarf named SDSS 1228 + 1040 outside our solar system.

Using 3 telescopes: Sloan Digital Sky Survey (on Mount Apache, New Mexico, USA), Herschel (on Canary Islands) and Galaxy Evolution Explorer (circling the Earth), researchers saw spectra emitted from a disk of metal dust flying around SDSS white dwarf 1228 + 1040.

The red metal dust disk is all that remains of the ill-fated planet when it approaches too close to a white dwarf.(Photo: Newscientist)

The spectral analysis results showed that this metal dust disk contains calcium, magnesium, and iron. The distance between it and the dwarf is about 100 times shorter than the distance from Mercury to the Sun. At that distance, radiation from a white dwarf is enough to make the temperature on the dust disk rise to 4,723 degrees C.

The spectrum also shows that the white dwarf's atmosphere is rich in magnesium. This means that matter from the disk of dust is falling to the star. Due to the enormous gravitational force of the white dwarf, the large-density elements on its surface were attracted to the interior. Magnesium is not attracted to the core due to its low mass.

" Ghost " planets

To explain all of these phenomena, Boris Gaensicke, the leader of the research team, suggested that a small planet was pulled towards the white dwarf by gravitational force. After being shredded, the remains of the ill-fated were the hot metal dust.

The location of the dust disk supports this hypothesis."Planets must be torn apart at this distance, " said Tom Marsh, a member of the research team.

The destruction of the planet also shows one thing: Many planets are " hiding " in planetary systems , because when a star swells to become a red giant, it will push it all. Smaller planets in the range have a radius equal to the distance from the Sun to Mars. Therefore, the fact that a " wandering " planet is close to the white dwarf proves that it is attracted here by the gravitational force of the planets outside the solar system it resides. Their massive gravitational force pulled the ill-fated planet toward the white dwarf.

Benjamin Zuckerman of the University of California in Los Angeles (USA), who published evidence of the existence of dust disks around white dwarfs, said that the new discovery is the latest evidence of white dwarfs. destroy the planet.

"It is possible that many planets have escaped the destruction of red giants. The gravitational effects of one or more such planets may cause this phenomenon," he said.

Ted von Hippel at the University of Texas, Austin (USA) argues that dust disks may be just the remains of white dwarfs in the final stages of life. However, he did not explain why the dust disk does not have hydrogen, the element that accounts for the largest proportion (about 70%) in the material composition of the stars.

" If the planet phenomenon is destroyed by a white dwarf is correct, we will better understand the fate of planetary systems like the solar system, " Ted said. " There is not much research about the future of planetary systems when a star becomes a red giant and then a white dwarf. This discovery helps us understand more about the final stages of a planetary system ".

Viet Linh