Hubble and several other major observatories have captured images of a system in which a white dwarf has so disrupted its environment that it is “cannibalizing” asteroids and/or minor local planets. A unique opportunity to study, 86 light years away, what G238-44 is made of.
And perhaps the (very distant) future of our own stellar environment!
A very special star
For its end of life, a star like ours provides a spectacle that is both very slow and particularly destabilizing. At the end of its main sequence, our Sun will transform into a red giant, of a diameter such that Mercury, Venus, the Earth and perhaps even Mars will be partially or totally vaporized…
Before exhausting its fusion fuel, and moving on to another stage, that of the white dwarf, where part of its mass is ejected into a planetary nebula and where only the core of the star remains, which will cool slowly for billions of years.
A process that can already be observed elsewhere, as with the white dwarf G238-44. The latter has been at its last stage for about 100 million years, and the disturbances these stellar changes have caused are still generating a veritable game of billiards, leading to the disintegration and then the accretion of millions of tons of material into the atmosphere of this star.
Familiar Atoms
Thanks to the archives of data from the Hubble telescope, but also from the former FUSE ultraviolet telescope and the Keck Observatory in Hawaii, it was possible to determine which building blocks make up this agglomerate of matter attracted and destroyed by the white dwarf. And for the first time, all the clues show that there are rocky and metallic materials, at the same time as ice: nitrogen, oxygen, magnesium, silicon, iron and other elements…
The quantities show that it is not (for now) the disintegration of a large planet, but rather one or more asteroids or a small moon. These observations were possible thanks to two years of studies and measurements of this system at 86 light years.
Longer sightings to come?
As in our own Solar System, there have therefore been small frozen celestial bodies there, but their composition seems significantly different. ” Nitrogen iron and ice ratios suggest large differences in planetary formation, because there are no Solar System objects with these proportions “, we learn from NASA.
It is also possible that several very different objects are now part of the debris cloud around G238-44, which continues to absorb or cannibalize small bodies around it. Small bodies that have been able to remain stable for billions of years therefore see their orbit disturbed by others, and by their star, before breaking up…
Source : NASA
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