A new study suggests that distant X-rays may be the most direct evidence of the remains of a disintegrating planet colliding with a star’s carcass.
White Dwarf is the cool, dim core of dead stars left behind after mid-sized stars have exhausted their fuel and shed their outer layers. They are usually about the size of Earth, and one day our sun will become a white dwarf, as well as about 97% stars.
Previous research has shown that the atmospheres of 25% to 50% of white dwarfs possess traces of elements heavier than hydrogen and helium, such as iron, calcium and magnesium. This is odd, since “white dwarfs are extremely dense objects and have surface gravity about 100,000 times stronger than Earth’s,” said study lead author Tim Cunningham, an astrophysicist at The University of Warwick in the UK, told Space.com. “This puts the heavy elements out of view for very short periods of time. This means that the heavy elements observed on the surface recently must have come from outside the white dwarf.”
Astronomers have assumed that these heavy elements are remnants of planets, asteroids or comets that have rained on these stellar ruins. Previous studies have also detected signs of planetary debris and disks of debris orbiting white dwarfs, giving confidence that matter may fall to their surfaces.
“Measuring how and how quickly the residual planetary matter falls to the white dwarf’s surface has many important implications, including for planet formation and other components,” Cunningham said. alien matter.
However, although the heavy elements in the white dwarf’s atmosphere suggest that dead stars have consumed the remnants of the planet in the recent past, and the rocks orbiting them suggest that they may do as well. So in the future, there is no direct evidence that white dwarfs were actively devouring such rocky matter at the time.
In the new study, the researchers analyzed the white dwarf star G29-38. This stellar remnant is about 60% mass of the sun and is located about 50 light-years from Earth, in the constellation Pisces.
Previous research showed that matter falling to white dwarfs from companion stars could be emitted X ray. However, to date, there is no evidence of X-rays from planetary matter hitting a white dwarf.
Detecting any X-rays from white dwarfs is difficult, as a small amount of X-ray radiation reaching Earth can be lost among other bright X-ray sources in the sky. So astronomers took advantage of NASA’s Chandra X-ray Observatory, which is commonly used to detect X-rays from black hole and neutron star is accumulating new material, for analysis G29-38.
Using Chandra, the researchers were able to isolate G29-38 from other X-ray sources. For the first time, they viewed X-rays from an isolated white dwarf star.
“What’s exciting with our X-ray detection is that we are detecting emission from the moment this planetary debris hit the stellar surface, providing the first direct evidence that These systems are being built.
The luminosity of the X-rays from G29-38 shows that about 1,800 tons (1,630 tons) of matter fall to the white dwarf every second. The scientists note that this accretion rate inferred from X-ray data matches previous estimates of accretion rates deduced from heavy elements seen in white dwarf atmospheres. “We now have an independent way to test decades-old theoretical models,” says Cunningham.
Now that astronomers have detected X-rays from a white dwarf star accumulating planetary matter, “I hope that we will find more,” Cunningham said. “The main problem here is that these sources are very faint compared to other X-ray sources such as accretion black holes and neutron stars. This means we need long observations to detect them. But the good news is that more sensitive x-ray instruments are planned to be launched, such as ATHENA [the Advanced Telescope for High Energy Astrophysics, planned by the European Space Agency]will be indispensable for this field of research. “
Detailed scientists their discovery online February 9 in the journal Nature.
https://www.space.com/zombie-star-dead-planet-snack The ‘zombie’ star was caught eating snacks on the dead planet