(Press-News.org) Astrophysicists have found the first evidence of a water-rich rocky planetary body outside our solar system in its shattered remains orbiting a white dwarf.
A new study by scientists at the Universities of Warwick and Cambridge published in the journal Science analysed the dust and debris surrounding the white dwarf star GD61 170 light years away.
Using observations obtained with the Hubble Space Telescope and the large Keck telescope on Hawaii, they found an excess of oxygen – a chemical signature that indicates that the debris had once been part of a bigger body originally composed of 26 per cent water by mass. By contrast, only approximately 0.023 per cent of the Earth's mass is water.
Evidence for water outside our solar system has previously been found in the atmosphere of gas giants, but this study marks the first time it has been pinpointed in a rocky body, making it of significant interest in our understanding of the formation and evolution of habitable planets and life.
We know from our own solar system that the dwarf planet Ceres contains ice buried beneath an outer crust, and the researchers draw a parallel between the two bodies. Scientists believe that bodies like Ceres were the source of the bulk of our own water on Earth.
The researchers suggest it is most likely that the water detected around the white dwarf GD 61 came from a minor planet at least 90 km in diameter but potentially much bigger, that once orbited the parent star before it became a white dwarf.
Like Ceres, the water was most likely in the form of ice below the planet's surface. From the amount of rocks and water detected in the outer envelope of the white dwarf, the researchers estimate that the disrupted planetary body had a diameter of at least 90km.
However, because their observations can only detect what is being accreted in recent history, the estimate of its mass is on the conservative side.
It is likely that the object was as large as Vesta, the largest minor planet in the solar system. In its former life, GD 61 was a star somewhat bigger than our Sun, and host to a planetary system.
About 200 million years ago, GD 61 entered its death throes and became a white dwarf, yet, parts of its planetary system survived. The water-rich minor planet was knocked out of its regular orbit and plunged into a very close orbit, where it was shredded by the star's gravitational force. The researchers believe that destabilising the orbit of the minor planet requires a so far unseen, much larger planet going around the white dwarf.
Professor Boris Gänsicke of the Department of Physics at the University of Warwick "At this stage in its existence, all that remains of this rocky body is simply dust and debris that has been pulled into the orbit of its dying parent star.
"However this planetary graveyard swirling around the embers of its parent star is a rich source of information about its former life.
"In these remnants lie chemical clues which point towards a previous existence as a water-rich terrestrial body.
"Those two ingredients – a rocky surface and water – are key in the hunt for habitable planets outside our solar system so it's very exciting to find them together for the first time outside our solar system."
Lead author Jay Farihi, from Cambridge's Institute of Astronomy, said: "The finding of water in a large asteroid means the building blocks of habitable planets existed – and maybe still exist – in the GD 61 system, and likely also around substantial number of similar parent stars.
"These water-rich building blocks, and the terrestrial planets they build, may in fact be common – a system cannot create things as big as asteroids and avoid building planets, and GD 61 had the ingredients to deliver lots of water to their surfaces," Farihi said.
"Our results demonstrate that there was definitely potential for habitable planets in this exoplanetary system."
For their analysis , the researchers used ultraviolet spectroscopy data obtained with the Cosmic Origins Spectrograph on board the Hubble Space Telescope of the white dwarf GD 61. As the atmosphere of the Earth blocks the ultraviolet light, such study can only be carried out from space.
Additional observations were obtained with the 10m large mirror of the W.M. Keck Observatory on Mauna Kea on Hawaii.
The Hubble and Keck data allows the researchers to identify the different chemical elements that are polluting the outer layers white dwarf. Using a sophisticated computer model of the white dwarf atmosphere, developed by Detlev Koester from the University of Kiel, they can then infer the chemical composition of the shredded minor planet.
To date observations of 12 destroyed exoplanets orbiting white dwarves have been carried out, but this is the first time the signature of water has been found.
INFORMATION:
Professor Boris Gänsicke is available for interview on +44 (0) 7904 444830 or email Boris.Gaensicke@warwick.ac.uk
For a copy of the image, University of Warwick press officer Anna Blackaby is available on +44 (0)2476 676910 or +44 (0)7785 433155 or a.blackaby@warwick.ac.uk.
Please email scipak@aaas.org for a copy of the paper.
The study Evidence for Water in the Rocky Debris of a Disrupted Extrasolar Minor Planet was published in the journal Science.
It was authored by J Farihi of the University of Cambridge, B Gänsicke of the University of Warwick and D Koester of the University of Kiel.
This work is based on observations made with the Hubble Space Telescope which is operated by the Association of Universities for Research in Astronomy under NASA contract NAS 5-26555. These observations are associated with program 12474. Some of the data were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. J. Farihi acknowledges support from the United Kingdom Science and Technology Facilities Council in the form of an Ernest Rutherford Fellowship (ST/J003344/1). The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement no. 267697 (WDTracer).
B.T. G¨ansicke was supported in part by the UK Science and Technology Facilities Council
(ST/I001719/1).
Water discovered in remnants of extrasolar rocky world orbiting white dwarf
2013-10-11
ELSE PRESS RELEASES FROM THIS DATE:
Watery asteroid discovered in dying star points to habitable exoplanets
2013-10-11
Astronomers have found the shattered remains of an asteroid that contained huge amounts of water orbiting an exhausted star, or white dwarf. This suggests that the star GD 61 and its planetary system – located about 150 light years away and at the end of its life – had the potential to contain Earth-like exoplanets, they say.
This is the first time that both water and a rocky surface - two "key ingredients" for habitable planets - have been found together beyond our solar system.
Earth is essentially a 'dry' planet, with only 0.02% of its mass as surface water, so oceans ...
Urine biomarkers reveal mitochondrial dysfunction in diabetic kidney disease
2013-10-11
Researchers at the University of California, San Diego School of Medicine have identified 13 metabolites – small molecules produced by cellular metabolism – that are significantly different in patients with diabetes and chronic kidney disease compared to healthy controls.
Twelve of the 13 metabolites are linked to mitochondrial function, suggesting that suppression of mitochondria – the powerhouses of cells – is a fundamental characteristic of diabetic kidney disease. The findings are published in the November edition of the Journal of the American Society of Nephrology.
"This ...
Researchers discover innate virus-killing power in mammals
2013-10-11
RIVERSIDE, Calif. — Scientists have a promising new approach to combating deadly human viruses thanks to an educated hunch by University of California, Riverside microbiology professor Shou-Wei Ding, and his 20 years of research on plants, fruit flies, nematodes and mice to prove his theory true.
Researchers led by Ding, who heads a lab in UC Riverside's Institute for Integrative Genome Biology, have discovered that, like plants and invertebrate animals, mammals use the RNA interference (RNAi) process to destroy viruses within their own cells.
Their findings will be ...
Ancient DNA unravels Europe's genetic diversity
2013-10-11
Ancient DNA recovered from a time series of skeletons in Germany spanning 4,000 years of prehistory has been used to reconstruct the first detailed genetic history of modern-day Europeans.
The study, published today in Science, reveals dramatic population changes with waves of prehistoric migration, not only from the accepted path via the Near East, but also from Western and Eastern Europe.
The research was a collaboration between the Australian Centre for Ancient DNA (ACAD), at the University of Adelaide, researchers from the University of Mainz, the State Heritage ...
New theory of synapse formation in the brain
2013-10-11
Jülich, 10 October 2013 – The human brain keeps changing throughout a person's lifetime. New connections are continually created while synapses that are no longer in use degenerate. To date, little is known about the mechanisms behind these processes. Jülich neuroinformatician Dr. Markus Butz has now been able to ascribe the formation of new neural networks in the visual cortex to a simple homeostatic rule that is also the basis of many other self-regulating processes in nature. With this explanation, he and his colleague Dr. Arjen van Ooyen from Amsterdam also provide ...
International team uncovers mechanism for natural plant immunity
2013-10-11
Scientists in Norwich and China have, for the first time, uncovered exactly how an immune receptor mediating plants' natural immunity to bacteria works.
The research has important implications for developing broad-spectrum disease resistance in crops.
UK researchers at The Sainsbury Laboratory in Norwich, in a close collaboration with Chinese scientists at Tsinghua University and the Chinese Academy of Sciences in Beijing have shared their findings in a paper published this week in Science.
TSL senior scientist Prof. Cyril Zipfel said: "Plants, like humans, have an ...
Study finds high-risk travelers account for nearly 1 in 5 persons seeking pre-travel advice
2013-10-11
(Boston) -- Researchers from Boston University Schools of Medicine (BUSM) and Public Health (BUSPH) and Boston Medical Center (BMC) have found that high-risk travelers account for nearly 20 percent of patients using the five clinics of the Boston Area Travel Medicine Network (BATMN). The study, which appears online in Mayo Clinic Proceedings, also found that these travelers often visited destinations with malaria and typhoid risk.
In 2010, an estimated 935 million travelers crossed international borders, including 28.5 million from the U.S. Certain travelers are at greater ...
Iron in the Earth's core weakens before melting
2013-10-11
The iron in the Earth's inner core weakens dramatically before it melts, explaining the unusual properties that exist in the moon-sized solid centre of our planet that have, up until now, been difficult to understand.
Scientists use seismic waves - pulses of energy generated during earthquakes - to measure what is happening in the Earth's inner core, which at 6000 km beneath our feet is completely inaccessible.
Problematically for researchers, the results of seismic measurements consistently show that these waves move through the Earth's solid inner core at much slower ...
Kissing helps us find the right partner -- and keep them
2013-10-11
What's in a kiss? A study by Oxford University researchers suggests kissing helps us size up potential partners and, once in a relationship, may be a way of getting a partner to stick around.
'Kissing in human sexual relationships is incredibly prevalent in various forms across just about every society and culture,' says Rafael Wlodarski, the DPhil student who carried out the research in the Department of Experimental Psychology at Oxford University. 'Kissing is seen in our closest primate relatives, chimps and bonobos, but it is much less intense and less commonly used. ...
Newly discovered gene regulator could precisely target sickle cell disease
2013-10-11
Boston, Mass., October 10, 2013 – A research team from Dana-Farber/Boston Children's Cancer and Blood Disorders Center and other institutions has discovered a new genetic target for potential therapy of sickle cell disease (SCD). The target, called an enhancer, controls a molecular switch in red blood cells called BCL11A that, in turn, regulates hemoglobin production.
The researchers—led by Daniel Bauer, MD, PhD, and Stuart Orkin, MD, of Dana-Farber/Boston Children's—reported their findings today in Science.
Prior work by Orkin and others has shown that when flipped ...