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Four white dwarf stars caught in the act of consuming 'earth-like' exoplanets
http://phys.org ^ | May 03, 2012 | Provided by Royal Astronomical Society

Posted on 05/03/2012 11:12:43 AM PDT by Red Badger

University of Warwick astrophysicists have pinpointed four white dwarf stars surrounded by dust from shattered planetary bodies which once bore striking similarities to the composition of the Earth. The scientists publish their results in a paper in the journal Monthly Notices of the Royal Astronomical Society.

White dwarfs are the final stage of life of stars like our Sun, the residual cores of material left behind after their available fuel for nuclear reactions has been exhausted. Using the Hubble Space Telescope to carry out 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.

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 systems.

‘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 of the Sun, using the Cosmic Origin Spectrograph onboard the Hubble Space Telescope.

More information: http://arxiv.org/abs/1205.0167


TOPICS: Culture/Society; United Kingdom
KEYWORDS: catastrophism; cosmology; sourcetitlenoturl; space; stars; universe; xplanets

Rocky material in orbit around a white dwarf star (centre). Collisions turn larger material into dust, some of which then rains down on to the white dwarf. Credit: © Mark A. Garlick / space-art.co.uk / University of Warwick

1 posted on 05/03/2012 11:12:57 AM PDT by Red Badger
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To: Red Badger

The party is almost over for white dwarf stars. Red dwarfs are where its at. They might last as long as a trillion years and they make up some 80% of the stars in the universe.


2 posted on 05/03/2012 11:30:46 AM PDT by cripplecreek (What does it profit a man if he gains the whole world but loses his soul?)
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To: cripplecreek

That’s waysist!.........


3 posted on 05/03/2012 11:35:44 AM PDT by Red Badger (Think logically. Act normally.................)
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To: Red Badger

Black holes are the tar baby of the universe.


4 posted on 05/03/2012 11:48:13 AM PDT by cripplecreek (What does it profit a man if he gains the whole world but loses his soul?)
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To: cripplecreek

And like the black ho’s here they suck in everything that passes by them weather it likes it or not.


5 posted on 05/03/2012 11:52:53 AM PDT by Jack Burton007 (This is Jack Burton in the Pork Chop Express, and I'm talkin' to whoever's listenin' out there.)
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To: Red Badger

is this another one of those ‘whites want to kill the handicap/dwarves’ stories?

;)


6 posted on 05/03/2012 12:02:37 PM PDT by sten (fighting tyranny never goes out of style)
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To: cripplecreek; sten

Scientists watch black hole feast on unlucky star:

http://phys.org/news/2012-05-scientists-black-hole-feast-unlucky.html


7 posted on 05/03/2012 12:22:03 PM PDT by Red Badger (Think logically. Act normally.................)
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To: Red Badger

I heard that some Great White economic stars in the West are eating up this planet.


8 posted on 05/03/2012 12:34:38 PM PDT by SaraJohnson
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To: Red Badger; KevinDavis; SunkenCiv

I came across this a while ago using the StumbleUpon add-on for Firefox.

http://www.multivax.com/last_question.html


9 posted on 05/03/2012 12:53:02 PM PDT by wastedyears (There can be only one.)
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To: Red Badger

Figures. robert reich always said eat the rich exo-planet.


10 posted on 05/03/2012 12:53:44 PM PDT by grumpygresh (Democrats delenda est; zero sera dans l'enfer bientot.)
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To: Red Badger
stars caught in the act of consuming 'earth-like' exoplanets

And a few galaxies away, Bamstar was caught in the act of consuming a Dog Star.

Bamstar tried to make light of it, but the hole thing came across as a very dark matter.

.

11 posted on 05/03/2012 1:25:11 PM PDT by repentant_pundit (Sammy's your uncle, but he behaves like a spoiled rotten kid.)
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To: repentant_pundit
The first white dwarf discovered (the Pup) is a companion star to the Dog Star (Sirius or Alpha Canis Majoris).

But I suppose everyone knows that.

12 posted on 05/03/2012 1:49:59 PM PDT by Verginius Rufus
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To: Jack Hydrazine; ELS; ToxicMich; Cronos; A_perfect_lady; Art in Idaho; perplyone; TheOldLady; ...
Bush's fault..


13 posted on 05/03/2012 4:58:32 PM PDT by KevinDavis (Go Mitt Go!!!)
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To: Red Badger

I’m gonna laugh if Zero gets elected again and still blames Bush near the end of his second term.


14 posted on 05/03/2012 5:04:04 PM PDT by Jack Hydrazine (It's the end of the world as we know it and I feel fine!)
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To: Jack Hydrazine
I’m gonna laugh if Zero gets elected again and still blames Bush near the end of his second term.

I'm gonna cry.....

15 posted on 05/04/2012 3:26:43 AM PDT by Vaquero (Don't pick a fight with an old guy. If he is too old to fight, he'll just kill you.)
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To: Red Badger

"I told you we were going to get caught!"

16 posted on 05/04/2012 3:40:02 AM PDT by central_va ( I won't be reconstructed and I do not give a damn.)
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To: repentant_pundit

That’s very nebulous.........may the Farce be with you.........


17 posted on 05/04/2012 6:36:21 AM PDT by Red Badger (Think logically. Act normally.................)
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To: 75thOVI; agrace; aimhigh; Alice in Wonderland; AndrewC; aragorn; aristotleman; Avoiding_Sulla; ...

Thanks wastedyears and kevindavis, and Red Badger for the topic.




18 posted on 05/05/2012 9:33:04 AM PDT by SunkenCiv (FReepathon 2Q time -- https://secure.freerepublic.com/donate/)
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To: KevinDavis; annie laurie; Knitting A Conundrum; Viking2002; Ernest_at_the_Beach; Mmogamer; ...

Thanks wastedyears and kevindavis, and Red Badger for the topic.

 
X-Planets
· join · view topics · view or post blog · bookmark · post new topic · subscribe ·
Google news searches: exoplanet · exosolar · extrasolar ·

19 posted on 05/05/2012 9:33:45 AM PDT by SunkenCiv (FReepathon 2Q time -- https://secure.freerepublic.com/donate/)
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To: KevinDavis; annie laurie; Knitting A Conundrum; Viking2002; Ernest_at_the_Beach; Mmogamer; ...

Thanks wastedyears and kevindavis, and Red Badger for the topic.

 
X-Planets
· join · view topics · view or post blog · bookmark · post new topic · subscribe ·
Google news searches: exoplanet · exosolar · extrasolar ·

20 posted on 05/05/2012 9:36:20 AM PDT by SunkenCiv (FReepathon 2Q time -- https://secure.freerepublic.com/donate/)
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To: Red Badger

If the earth’s core is molten lava and the planet has been around for millions and millions of years, how is it that that molten lava hasn’t cooled off and then finally hardened in all those years?


21 posted on 05/05/2012 11:48:55 AM PDT by Hot Tabasco (My 6 pack abs are now a full keg......)
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To: Hot Tabasco

One theory is radioactivity at the core.....


22 posted on 05/11/2012 5:26:43 PM PDT by Red Badger (Think logically. Act normally.................)
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