A team of astronomers from the University of California at Los Angeles (USA) has observed a white dwarf that feeds on asteroids and comets; is absorbing debris from both the interior and exterior of the system , suggesting that this object, located 86 light-years away from Earth, is destroying its entire star system.
“We’ve never seen these two types of objects cluster on a white dwarf at the same time,” said Ted Johnson, a UCLA physics and astronomy student and co-author of the paper. “By studying these white dwarfs, we hope to gain a better understanding of planetary systems that are still intact.”
cosmic cannibalism
This is the first case of cosmic cannibalism in which astronomers have observed a white dwarf that consumes both rocky-metallic material, probably from a nearby asteroid, and icy material, which is presumed to come from a body similar to those found in the Kuiper belt, the circumstellar disk in the outer solar system, which extends from the orbit of Neptune to about 50 astronomical units from our star.
This case of cosmic cannibalism was identified with the help of archival data from the Hubble Space Telescope and other NASA observatories. The researchers drew these surprising conclusions and evidence of stellar cannibalism based on analysis of material captured by the atmosphere of the nearby white dwarf star G238-44.
Recall that a white dwarf forms when a low-mass star like our Sun runs out of most of its nuclear fuel. It is usually very dense and the size of a planet. When they run out of hydrogen to burn, they resort to helium fusion in their core. This is where stars swell and can engulf their closest planet. As the star continues to age , it eventually becomes a white dwarf. But its initial period of transformation, which can last about 100 million years, is tremendously tumultuous for everything around it.
If this were our solar system , the future white dwarf of our star would be feeding on the remains of rocky planets and the asteroid belt, as well as the region full of icy objects like Arrokoth, beyond the orbit of Neptune, in the Kuiper belt.
search for life
The fact of having discovered this case of cosmic cannibalism is interesting not only because of the discovery itself, but because these icy objects are attributed the fact of colliding with dry rocky planets in the solar system and “irrigating” them. These comets and asteroids are believed to have brought water to Earth billions of years ago, thereby creating the conditions necessary for life as we know it.
“Life as we know it requires a rocky planet covered with a variety of elements such as carbon, nitrogen and oxygen,” said Benjamin Zuckerman, a UCLA professor and co-author of the research. “The abundance of the elements we see in this white dwarf appears to require a parent body that is both rocky and volatile-rich, the first example we have found among studies of hundreds of white dwarfs.”
The UCLA research group, along with colleagues from UC San Diego and the University of Kiel in Germany, have worked for more than two years to unravel the mystery of G238-44 by analyzing elements detected in the white dwarf star. Their analysis included data from NASA’s retired Far-Ultraviolet Spectroscopic Explorer, the Keck Observatory’s High-Resolution Echelle Spectrometer in Hawaii, and the Hubble Space Telescope’s Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph.
The researchers are now looking at the final scenario for the evolution of the Sun, in about 5 billion years, in which the Earth could completely vaporize with the other inner planets.
Reference: NASA’s Goddard Space Flight Center / NASA, ESA, Joseph Olmsted (STScI)
