Science Current Events | Science News |

Four white dwarf stars caught in the act of consuming 'earth-like' exoplanets

May 04, 2012

University of Warwick astrophysicists have pinpointed four white dwarfs surrounded by dust from shattered planetary bodies which once bore striking similarities to the composition of the Earth.

Using the Hubble Space Telescope for the biggest survey to date of the chemical composition of the atmospheres of white dwarf stars, the researchers found that the most frequently occurring elements in the dust around these four white dwarfs were oxygen, magnesium, iron and silicon - the four elements that make up roughly 93 per cent of the Earth.

However an even more significant observation was that this material also contained an extremely low proportion of carbon, which matched very closely that of the Earth and the other rocky planets orbiting closest to our own Sun.

This is the first time that such low proportions of carbon have been measured in the atmospheres of white dwarf stars polluted by debris. Not only is this clear evidence that these stars once had at least one rocky exoplanet which they have now destroyed, the observations must also pinpoint the last phase of the death of these worlds.

The atmosphere of a white dwarf is made up of hydrogen and/or helium, so any heavy elements that come into their atmosphere are dragged downwards to their core and out of sight within a matter of days by the dwarf's high gravity. Given this, the astronomers must literally be observing the final phase of the death of these worlds as the material rains down on the stars at rates of up to 1 million kilograms every second.

Not only is this clear evidence that these stars once had rocky exoplanetary bodies which have now been destroyed, the observations of one particular white dwarf, PG0843+516, may also tell the story of the destruction of these worlds.

This star stood out from the rest owing to the relative overabundance of the elements iron, nickel and sulphur in the dust found in its atmosphere.

Iron and nickel are found in the cores of terrestrial planets, as they sink to the centre owing to the pull of gravity during planetary formation, and so does sulphur thanks to its chemical affinity to iron.

Therefore, researchers believe they are observing White Dwarf PG0843+516 in the very act of swallowing up material from the core of a rocky planet that was large enough to undergo differentiation, similar to the process that separated the core and the mantle of the Earth.

The study entitled "The chemical diversity of exo-terrestrial planetary debris around white dwarfs" by B. T. Gänsicke, D. Koester, J. Farihi, J. Girven, S.G.Parsons, and E. Breedt is accepted for publication in the Monthly Notices of the Royal Astronomical Society.

Professor Boris Gänsicke of the Department of Physics at the University of Warwick, who led the study, said the destructive process which caused the discs of dust around these distant white dwarfs is likely to one day play out in our own solar system.

"What we are seeing today in these white dwarfs several hundred light years away could well be a snapshot of the very distant future of the Earth.

"As stars like our Sun reach the end of their life, they expand to become red giants when the nuclear fuel in their cores is depleted.

"When this happens in our own solar system, billions of years from now, the Sun will engulf the inner planets Mercury and Venus.

"It's unclear whether the Earth will also be swallowed up by the Sun in its red giant phase - but even if it survives, its surface will be roasted.

"During the transformation of the Sun into a white dwarf, it will lose a large amount of mass, and all the planets will move further out.

"This may destabilise the orbits and lead to collisions between planetary bodies as happened in the unstable early days of our solar system. This may even shatter entire terrestrial planets, forming large amounts of asteroids, some of which will have chemical compositions similar to those of the planetary core.

"In our solar system, Jupiter will survive the late evolution of the Sun unscathed, and scatter asteroids, new or old, towards the white dwarf.

"It is entirely feasible that in PG0843+516 we see the accretion of such fragments made from the core material of what was once a terrestrial exoplanet."

The University of Warwick led team surveyed more than 80 white dwarfs within a few hundred light years, using the Cosmic Origin Spectrograph on board the Hubble Space Telescope.

University of Warwick

Related White Dwarf Current Events and White Dwarf News Articles

Stellar cannibalism transforms star into brown dwarf
Astronomers have detected a sub-stellar object that used to be a star, after being consumed by its white dwarf companion.

Rotational clock for stars needs recalibration
New work from a team of astronomers led by Carnegie's Jennifer van Saders indicates that one recently developed method for determining a star's age needs to be recalibrated for stars that are older than our Sun.

Titan helps researchers explore explosive star scenarios
Exploding stars may seem like an unlikely yardstick for measuring the vast distances of space, but astronomers have been mapping the universe for decades using these stellar eruptions, called supernovas, with surprising accuracy.

Asteroid ripped apart to form star's glowing ring system
The sight of an asteroid being ripped apart by a dead star and forming a glowing debris ring has been captured in an image for the first time.

The glowing halo of a zombie star
Led by Christopher Manser, a PhD student at the University of Warwick in the United Kingdom, the team used data from ESO's Very Large Telescope (VLT) and other observatories to study the shattered remains of an asteroid around a stellar remnant -- a white dwarf (called SDSS J1228+1040) [1].

Hubble uncovers the fading cinders of some of our galaxy's earliest homesteaders
Using NASA's Hubble Space Telescope to conduct a "cosmic archaeological dig" at the very heart of our Milky Way galaxy, astronomers have uncovered the blueprints of our galaxy's early construction phase.

Suzaku finds common chemical makeup at largest cosmic scales
A new survey of hot, X-ray-emitting gas in the Virgo galaxy cluster shows that the elements needed to make stars, planets and people were evenly distributed across millions of light-years early in cosmic history, more than 10 billion years ago.

Cosmic 'Death Star' is destroying a planet
The Death Star of the movie Star Wars may be fictional, but planetary destruction is real. Astronomers announced today that they have spotted a large, rocky object disintegrating in its death spiral around a distant white dwarf star. The discovery also confirms a long-standing theory behind the source of white dwarf "pollution" by metals.

Dying star suffers 'irregular heartbeats
Some dying stars suffer from 'irregular heartbeats', research led by astronomers at the University of Warwick has discovered.

Mystery of exploding stars yields to astrophysicists
A longstanding mystery about the tiny stars that let loose powerful explosions known as Type Ia supernovae might finally be solved.
More White Dwarf Current Events and White Dwarf News Articles

White Dwarf: First Deployment

White Dwarf: First Deployment
by Paul Abbott (Author), Steven Pressfield (Editor), Amanda Brown (Editor), Layla Fisek (Editor), Kate McDaniels McDaniels (Editor)

With a brutal Gulf War pedigree, and in uniform as LAPD patrol officers, Harrington and Vendetti navigate the city’s sprawling terrain, encountering the desperate, the depraved, and the empty. What follows is a series of gruesome occurrences with no apparent logic to them. Allowed to witness their hate and vengeance, it appears they merely cause mayhem for mayhem’s sake. They steal, use, and sell drugs, but that’s only when they're not mutilating corpses or driving people to suicide. Theirs is a filthy and misogynistic world ruled by whores, drugs, and retribution. There is nobody in this world to cheer for, yet even in the deeply flawed there is a hint of a soul. The actions of these sociopathic, dead-eyed men hint, ironically, where it lies. With every new soon-to-be-terrorized...

Snow White and the Seven Dwarfs (Disney Princess) (Little Golden Book)

Snow White and the Seven Dwarfs (Disney Princess) (Little Golden Book)
by RH Disney (Author), RH Disney (Illustrator)

Walt Disney's classic Snow White and the Seven Dwarfs is being released on Platinum Edition DVD. Now new and old fans can relive the magic of this beloved film as it is retold in a beautiful full-color Little Golden Book!

  Black Holes, White Dwarfs and Neutron Stars: The Physics of Compact Objects
by Stuart L. Shapiro (Author), Saul A. Teukolsky (Author)

This self-contained textbook brings together many different branches of physics--e.g. nuclear physics, solid state physics, particle physics, hydrodynamics, relativity--to analyze compact objects. The latest astronomical data is assessed. Over 250 exercises.

Snow White and the Seven Dwarfs: The Story of Snow White (Disney Princess (Disney Press Unnumbered))

Snow White and the Seven Dwarfs: The Story of Snow White (Disney Princess (Disney Press Unnumbered))
by Disney Book Group (Author), Disney Storybook Art Team (Illustrator)

Snow White is the fairest in the land. When the wicked queen wants that title for herself, Snow White flees into the forest where she meets the Seven Dwarfs. But the queen is determined to be the fairest in the land. Will Snow White ever escape her evil clutches and live happily ever after? This collectible storybook includes beautiful, full color art in the style of the beloved film, Snow White and the Seven Dwarfs.

Snow White Coloring Book

Snow White Coloring Book
by Fabiana Attanasio (Author)

Kids can bring their favorite tales and characters to life through the magic of coloring. This enchanting retelling of Snow White will stimulate children’s creativity as they put their own mark on Fabiana Attanasio’s illustrations and make every page unique.
Young readers will also the enjoy adaptation of the original story, retold in fresh and modern language. Plus, there’s a removable poster to color in and hang on the wall—so budding artists can admire their beautiful work.

Unlocking the Secrets of White Dwarf Stars (Astronomers' Universe)

Unlocking the Secrets of White Dwarf Stars (Astronomers' Universe)
by Hugh Van Horn (Author)

White dwarfs, each containing about as much mass as our Sun but packed into a volume about the size of Earth, are the endpoints of evolution for most stars. Thousands of these faint objects have now been discovered, though only a century ago only three were known. They are among the most common stars in the Milky Way Galaxy, and they have become important tools in understanding the universe. Yet a century ago only three white dwarfs were known.  The existence of these stars completely baffled the scientists of the day, and solving the mysteries of these strange objects required revolutionary advances in science and technology, including the development of quantum physics, the construction and utilization of large telescopes, the invention of the digital computer, and the ability to make...

Snow-White and the Seven Dwarfs: A Tale from the Brothers Grimm (Sunburst Book)

Snow-White and the Seven Dwarfs: A Tale from the Brothers Grimm (Sunburst Book)
by Jacob Grimm (Author), Wilhelm K. Grimm (Author), Nancy Ekholm Burkert (Illustrator), Randall Jarrell (Illustrator)

Retells the tale of the beautiful princess whose lips were red as blood, skin was white as snow, and hair was as black as ebony.

Snow White and the Seven Dwarfs (Fairytale Boards)

Snow White and the Seven Dwarfs (Fairytale Boards)
by Parragon Books (Author)

Find out what happens when Snow White finds a little cottage in the woods and makes seven new friends. With beautiful illustrations to enjoy again and again.

Snow White and the 77 Dwarfs

Snow White and the 77 Dwarfs
by Davide Cali (Author), Raphaelle Barbanegre (Illustrator)

Snow White is on the run from an evil witch when she comes across some dwarfs in the forest. They agree to take her in and keep her safe if she will help them with their chores. She soon realizes she's taking on a lot more than she bargained for. 77 breakfasts to make, 77 lunches to pack (don't forget the juice boxes!), 77 pairs of pants to mend and a whole lot of dishes. Eventually Snow White decides to take her chances with the witch. There's a surprise ending... well, it may not be so surprising. This is a hilarious retelling of the classic tale, with bright, energetic illustrations featuring busy dwarfs, and the even busier Snow White.

Snow White and the Seven Dwarfs

Snow White and the Seven Dwarfs
by Walt Disney Productions (Author), Walt Productions Sta Disney (Author)

Classic fable of seven eccentric little men who, over time, befriend a young woman and share an adventurous journey of life with her.

© 2016