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

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.

Rogue supernovas likely flung into space by black hole slingshots
Rogue supernovas that explode all alone in deep space present an astronomical mystery. Where did they come from? How did they get there? The likely answer: a binary black hole slingshot, according to a new study by Ryan Foley, a professor of astronomy and physics at the University of Illinois.

Seeing a supernova in a new light
Type Ia supernovae are the "standard candles" astrophysicists use to chart distance in the Universe. But are these dazzling exploding stars truly all the same? To answer this, scientists must first understand what causes stars to explode and become supernovae.

Retirement in the suburbs
Astronomers using the NASA/ESA Hubble Space Telescope have, for the first time, collected a census of young white dwarf stars beginning their migration from the crowded centre of an ancient star cluster to its less populated outskirts.
More White Dwarf Current Events and White Dwarf News Articles

White Dwarf Magazine September 2013

White Dwarf Magazine September 2013
by Various (Author)

White Dwarf Monthly Magazine.

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!

Snow White at the Dwarf Colony

Snow White at the Dwarf Colony
by New Rise Press

What sort of mother would long to murder her own daughter because she was younger and more beautiful?

What power did the Queen hold over the Huntsman, that he would agree to murder that child?

What if the dwarfs were actually little people, rather than cute Disneyesque characters?

In the same vein as the author's prior CINDERELLA, this retelling of the classic fairy tale answers these questions and explores the themes of envy, shame, and narcissism from a fully psychological perspective.

Snow White and the Seven Dwarfs (Disney Princess) (Read-Aloud Board Book)

Snow White and the Seven Dwarfs (Disney Princess) (Read-Aloud Board Book)
by RH Disney (Author)

Now even the youngest Disney Princess fans can enjoy the classic story of Snow White and the Seven Dwarfs! This sturdy board book features stunning full-color art as well as simple, easy-to-read text.

Snow White and the Seven Dwarfs (Read-Along Storybook and CD)

Snow White and the Seven Dwarfs (Read-Along Storybook and CD)
by Disney Storybook Art Team (Illustrator)

Snow White's classic tale comes to life! Follow along as Snow White befriends the Seven Dwarfs, takes a bite of a magical apple, and lives happily ever after. Character voices and lively sound effects add to the magic in this enchanting storybook-and-CD set.

Snow White & the Eighth Dwarf

Snow White & the Eighth Dwarf

You always knew there was something fishy about Snow White's story, didn’t you? Seven lusty men. One young, nubile woman. Living innocently together in a cottage in the woods.

But life ain't no fairy tale.

Now Bitchy, the eighth dwarf, tells the real story of Snow White and it's nothing like you imagined. Or maybe it is.

White Dwarf Magazine August 2013

White Dwarf Magazine August 2013
by Various (Author)

White Dwarf magazine

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: The Art and Creation of Walt Disney's Classic Animated Film

Snow White and the Seven Dwarfs: The Art and Creation of Walt Disney's Classic Animated Film
by J.B. Kaufman (Author)

Released in 2012, in conjunction with the 75th anniversary of Snow White and the Seven Dwarfs, this book tells the fascinating story of the making of Walt Disney's groundbreaking animated classic. More than 250 artworks, including rarely seen concept sketches, background paintings, and cels illustrate the genius of Walt Disney and the creative vision of the artists who produced a beloved milestone in cinematic history.

In 1933, Walt Disney was a rising star in the world of animation, just beginning to become a household name. Ambitious new ideas emerged from the Disney studio on a regular basis, and the film world waited eagerly to see what the creative young filmmaker would do next. The answer surprised them all: a full-length animated feature film, based on the traditional tale...

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.

© 2015