The Hubble Space Telescope has spotted evidence of a white dwarf star devouring rocky and icy material from its own system, suggesting that water and other volatiles might be common in the outer reaches of planetary systems.
Astronomers used archival data from the Hubble Space Telescope and other observatories to analyze the spectral properties of the white dwarf star G238-44. The elements detected on the star's surface show that the dead star is siphoning debris from its system's inner and outer reaches.
"We have never seen both of these kinds of objects accreting onto a white dwarf at the same time," Ted Johnson, the lead researcher and a recent graduate of the University of California, Los Angeles, said in a statement. "By studying these white dwarfs, we hope to gain a better understanding of planetary systems that are still intact."
The observation of this cosmic death dance provides a unique opportunity to see what planets were made of when they first formed around the star and to confirm ideas about the violent and chaotic end stages of similar systems.
G238-44 is a former sunlike star that has shed its outer layers and stopped burning fuel through nuclear fusion. The discovery that the stellar corpse is simultaneously capturing material from its asteroid belt and Kuiper Belt-like regions, including icy bodies, is significant because it suggests that a "water reservoir" might be a common feature in the outer reaches of planetary systems.
"Life as we know it requires a rocky planet covered with a variety of elements, like carbon, nitrogen and oxygen," said Benjamin Zuckerman, professor emeritus in the UCLA Division of Astronomy and Astrophysics and co-author of the research. "The abundances of the elements we see on this white dwarf appear to require both a rocky and a volatile-rich parent body — the first example we've found among studies of hundreds of white dwarfs."
The research group included astronomers at UCLA; the University of California, San Diego; and Kiel University in Germany. The team's results were presented June 15 at an American Astronomical Society news conference.