This illustration shows a white dwarf star sucking debris from broken objects into a planetary system. The Hubble Space Telescope discovers the spectral nature of evaporated debris, which reveals a combination of rock-metal and ice material, components of the planets. The findings help describe the violent nature of evolved planetary systems and the composition of their decaying bodies. Credit: NASA, ESA, Joseph Olmsted (STScI)
Both rocky and icy bodies were identified among the debris on the surface of a white dwarf star
“Get your dead out!” rings in the air in the classic movie “Monty Python and the Holy Grail”, a cheerful parallel to what is happening around a white dwarf star in the nearby planetary system. The dead star “rings” with its own bell, urging the “dead” to gather in its footsteps. The white dwarf is all that remains after a sun-like star has exhausted its nuclear fuel and discarded most of its outer material – destroying objects in the planetary system that revolve around it. What remains is a group of players with unpredictable orbits who – despite protests that “they are not dead yet!” – will eventually be captured by the central star.
how do we know The bodies swallowed by the star leave treacherous “fingerprints” – captured by the Hubble Space Telescope and other NASA observatories – on its surface. Spectral evidence shows that the white dwarf sucks both rock and metal and ice material – debris and debris. , and from its external range. The discovery of evidence of ice bodies is intriguing, as it suggests that a “water reservoir” may be common on the edges of planetary systems, improving the chances of life as we know it.
A star’s death agonies have so violently destroyed its planetary system that an abandoned dead star, called a white dwarf, sucks debris from both the system’s inner and outer range. This is the first time astronomers have observed a white dwarf star that consumes both rock metal and ice material, ingredients of the planets. Archive data from NASA’s Hubble Space Telescope and other NASA observatories have been essential in diagnosing this case of space cannibalism. The findings help describe the violent nature of evolved planetary systems and can tell astronomers about the composition of newly formed systems. Credit: NASA’s Goddard Space Flight Center; Principal producer: Paul Morris
The dead star caught tearing up the planetary system
A star’s death agonies have so violently destroyed its planetary system that an abandoned dead star, called a white dwarf, sucks debris from both the system’s inner and outer range. This is the first time astronomers have observed a white dwarf star that consumes both rock metal and ice material, ingredients of the planets.
Archive data from NASA’s Hubble Space Telescope and other NASA observatories have been essential in diagnosing this case of space cannibalism. The findings help describe the violent nature of evolved planetary systems and can tell astronomers about the composition of newly formed systems.
The findings are based on an analysis of material captured by the atmosphere of the nearby white dwarf star G238-44. A white dwarf is what remains of a star like our Sun after it sheds its outer layers and stops burning fuel through nuclear fusion. “We’ve never seen both types of objects accumulate on a white dwarf at the same time,” said Ted Johnson, a lead researcher and recently a bachelor’s degree from the University of California, Los Angeles (UCLA). “By studying these white dwarfs, we hope to better understand the planetary systems that are still intact.
This illustrated diagram of the G238-44 planetary system traces its destruction. The little white dwarf star is in the center of the action. A very weak accretion disk consists of pieces of broken bodies falling on a white dwarf. Other asteroids and planetary bodies form a reservoir of material around the star. Larger gas giant planets may still exist in the system. Far farther away is a belt of icy bodies like comets that eventually feed on the dead star as well. Credit: NASA, ESA, Joseph Olmsted (STScI)
The findings are also intriguing, as small ice objects are responsible for pushing and “watering” the dry rocky planets in our solar system. Billions of years ago, comets and asteroids were thought to have supplied water to Earth, creating the conditions necessary for life as we know it. The composition of the bodies detected raining on the white dwarf suggests that ice reservoirs may be common among planetary systems, Johnson said.
“Life as we know it requires a rocky planet covered in various elements such as carbon, nitrogen and oxygen,” said Benjamin Zuckerman, a UCLA professor and co-author. “The abundance of elements we see on this white dwarf seems to require both a rocky and volatile parent body – the first example we found in the research of hundreds of white dwarfs.
Demolition derbies
Theories of the evolution of the planetary system describe the transition between the phases of the red giant and the white dwarf as a chaotic process. The star is rapidly losing its outer layers and the orbits of its planets are changing dramatically. Small objects, such as asteroids and dwarf planets, can get too close to giant planets and be sent down to the star. This study confirms the true scale of this violent chaotic phase, showing that within 100 million years after the onset of its white dwarf phase, the star is able to simultaneously capture and consume material from its asteroid belt and regions similar to the asteroid belt. Kuiper.
The calculated total mass that is ultimately absorbed by the white dwarf in this study may be no more than the mass of an asteroid or a small moon. Although the presence of at least two objects consumed by the white dwarf is not directly measured, one is probably rich in metals such as an asteroid and the other is an icy body similar to that found on the periphery of our solar system in the Kuiper Belt. . .
Although astronomers have cataloged more than 5,000 exoplanets, the only planet on which we have direct knowledge of its inner composition is Earth. The white dwarf cannibalism provides a unique opportunity to separate the planets and see what they are made of when they first formed around the star.
The team measured the presence of nitrogen, oxygen, magnesium, silicon and iron, among other elements. The discovery of iron in great abundance is evidence of metal nuclei on Earth planets such as Earth, Venus, Mars and Mercury. Unexpectedly high nitrogen content led them to conclude the presence of ice bodies. “The best match for our data was a mixture of almost two to one of the mercury-like material and the comet-like material, which consists of ice and dust,” Johnson said. “Iron metal and nitrogen ice suggest extremely different conditions for planetary formation. There is no known object in the solar system with so many of the two. “
Death of a planetary system
When a star like our Sun expands into a swollen red giant at the end of its life, it will throw out a mass by inflating its outer layers. One consequence of this could be the gravitational scattering of small objects such as asteroids, comets and moons from all other large planets. Like pinballs in an arcade game, surviving objects can be thrown into highly eccentric orbits.
“After the red giant phase, the remaining white dwarf star is compact – no bigger than Earth. The wayward planets get very close to the star and experience powerful tidal forces that tear them apart, creating a gaseous and dusty disk that eventually falls to the surface of the white dwarf, Johnson explained.
Researchers are looking at the final scenario for the evolution of the Sun after 5 billion years. The earth can be completely evaporated along with the inner planets. But the orbits of many of the asteroids in the main asteroid belt will be gravitationally disturbed by Jupiter and will eventually fall on the white dwarf, which will become the residual Sun.
For more than two years, a research group at UCLA, the University of California, San Diego and the University of Kiel in Germany has been working to unravel this mystery by analyzing elements found on a white dwarf star cataloged as G238-44. Their analysis includes data from NASA’s retired long-range ultraviolet spectroscopic researcher (FUSE), the Echelle high-resolution spectrometer Keck Observatory (HIRES) in Hawaii, and the Cosmic Origins Spectrograph (COS) of the Hubble Space Telescope Space Telescope and Space Telescope ).
The team’s results were presented at a press conference of the American Astronomical Society (AAS) on Wednesday, June 15, 2022.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, operates the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble research operations. STScI is administered to NASA by the Association of Universities for Research in Astronomy in Washington, DC
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