(Press-News.org) Based on a treasure trove of recent discoveries, astronomers now know that planets are remarkably plentiful in our galaxy and may be common throughout the Universe. Though planets appear to form readily, the actual process of planet formation remains a mystery and astronomers are searching for the missing pieces to this cosmic puzzle.
An international team of researchers using the new Atacama Large Millimeter/submillimeter Array (ALMA) telescope has discovered an intriguing clue that could help explain how rocky planets are able to evolve out of a swirling disk of dust and gas.
By imaging the outer regions of a young solar system known as Oph IRS 48, which resides approximately 390 light-years from Earth in the constellation Ophiuchus, astronomers have discovered a crescent-shaped structure known as a "dust trap." The researchers speculate that this newly discovered feature is actually a protective cocoon where the critical early steps of planet, asteroid, and comet formation can take place.
When astronomers try to model the evolution of dust grains into pre-planetary bodies, such as pebbles and boulders, they run into a problem. Once dust grains grow to a certain size, they tend to self-destruct, either by colliding with other grains or by being drawn into their central star. To get past this vexing size limit, astronomers have theorized that swirling eddies in the disk could create dust traps, regions that enable dust particles to cling together, eventually setting the stage for the formation of larger and larger objects.
"There is a major hurdle in the long chain of events that leads from tiny dust grains to planet-sized objects," said Til Birnstiel, a researcher at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and co-author on the paper published in the journal Science. "In computer models of planet formation, dust grains must grow from submicron sizes to objects up to ten times the mass of the Earth in just a few million years. But once particles grow larger enough, they begin to pick up speed and either collide, sending them back to square one, or slowly drift inward, thwarting further growth."
To save dust grains from this fate, astronomers have proposed that a vortex, essentially a "bump" in the disk, would produce an area of higher pressure and protect the growing dust grains.
Creating the dust trap, however, requires the helping hand of a very large object, such as a gas-giant planet or companion star. As this secondary object plows through the disk, it would clear a path around the star and produce the essential eddies and vortices in its wake.
Previous studies of Oph IRS 48 revealed a very uniform ring of carbon monoxide gas and small dust grains around the star, with no hints of a theorized dust trap. They did, however, detect a large gap between the inner and outer portions of the disk, which is a likely telltale sign that a very massive planet, on the order of 10 Jupiter masses, or a companion star was present. Such an object could produce the necessary conditions for a dust trap.
Using ALMA, the researchers were able to simultaneously observe both the gas and the much larger dust grains, revealing something the other telescopes could not: a lopsided bulge in the outer portion of the disk.
"At first the shape of the dust in the images was a complete surprise for us," said Nienke van der Marel, a Ph.D. student at Leiden Observatory in the Netherlands and lead author on the paper. "Instead of the ring we had expected to see, we found a very clear cashew-nut shape. We had to convince ourselves that this feature was real, but the strong signal and sharpness of the ALMA observations left no doubt about the structure."
Though the ALMA observations revealed only the outer structure of the disk, at more than 50 times the distance of the Earth to the Sun, the principle would still be the same closer to the star where rocky planets would form. "This structure we see with ALMA could be scaled down to represent what may be happening in the inner solar system where more Earth-like rocky planets would form," said Birnstiel. "In the case of these observations, however, we may be seeing something analogous to the formation of our Sun's Kuiper Belt or Oort Cloud, the region of our solar system where comets are believed to originate."
These observations were made with only a portion of ALMA's eventual full complement of 66 antennas. When the full array is in operation later this year, ALMA will have one of the sharpest visions of any astronomical observatory and will be an important tool in understanding the entire planet-formation process.
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ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
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SEATTLE – Fred Hutchinson Cancer Research Center scientists have, for the first time, mapped a young gene's short, dramatic evolutionary journey to becoming essential, or indispensable. In a study published online June 6 in Science, the researchers detail one gene's rapid switch to a new and essential function in the fruit fly, challenging the long-held belief that only ancient genes are important.
"We really haven't paid much attention to what is new, because there's so much emphasis on what is old," said Harmit Singh Malik, Ph.D., a member of the Hutchinson Center's ...
SEATTLE—China made substantial gains in health over the past two decades, including increases in life expectancy, reductions in child mortality, and declines in infectious diseases such as tuberculosis and lower respiratory infections. But with that success accompanies the growth of non-communicable diseases and risk factors such as tobacco use and high blood pressure, which could overwhelm the health system.
These are some of the findings published June 8 in The Lancet in an analysis by the Chinese Center for Disease Control and Prevention, Peking Union Medical College ...
Colonies of gannets maintain vast exclusive fishing ranges despite doing nothing to defend their territory from rival colonies, scientists have discovered.
A team of researchers led by the University of Leeds and the University of Exeter observed that northern gannets, which can fly hundreds of kilometres on a single fishing trip, avoided visiting the fishing grounds of gannets from neighbouring colonies.
The findings, published in the journal Science, could transform our understanding of animals' foraging patterns because individual gannets do nothing to enforce this ...
A protein profile of people with restless leg syndrome (RLS), identifies factors behind disrupted sleep, cardiovascular dysfunction and pain finds research in BioMed Central's open access journal Fluids and Barriers of the CNS. The research gives insights into the disorder, and could be useful in the development of new treatments.
It is not completely clear what causes RLS, also known as Willis Ekbom disease (WED), but in some people it is associated with iron deficiency in the brain, kidney failure, or low levels of the ' pleasure' neurotransmitter dopamine. It can ...
A gene expression study of grapevine berries grown in different Italian vineyards has highlighted genes that help buffer the plants against environmental change and may explain the different quality performances of grapevine when grown in different "terroirs". The research, reported in the open access journal Genome Biology, could be used to help identify and breed grapevine varieties better suited to climate change and improve berry and wine quality.
Much to the inconvenience of winemakers and drinkers, grapevine berries vary within berries on vines grown in different ...
This news release is available in German. "I think I can safely say that nobody understands quantum mechanics." Thus spoke the American physicist Richard Feynman — underlining that even leading scientists struggle to develop an intuitive feeling for quantum mechanics. One reason for this is that quantum phenomena often have no counterpart in classical physics. A typical example is the quantum entanglement: Entangled particles seem to directly influence one another, no matter how widely separated they are. It looks as if the particles can 'communicate' with one another ...
CAMBRIDGE, MA -- By activating a brain circuit that controls compulsive behavior, MIT neuroscientists have shown that they can block a compulsive behavior in mice — a result that could help researchers develop new treatments for diseases such as obsessive-compulsive disorder (OCD) and Tourette's syndrome.
About 1 percent of U.S. adults suffer from OCD, and patients usually receive antianxiety drugs or antidepressants, behavioral therapy, or a combination of therapy and medication. For those who do not respond to those treatments, a new alternative is deep brain stimulation, ...
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The report, HIV in the European Region: vulnerability and response, focuses on key populations most at risk of HIV infection: ...
(June 6, 2013 – Chicago, IL) When health care reform in Thailand increased payments to public hospitals for indigent care, more poor people sought medical treatment and infant mortality was reduced, even though the cost of medical care remained free for the poor, a new study shows.
The study, "The Great Equalizer: Health Care Access and Infant Mortality in Thailand," funded in part by the National Institutes of Health, found that reducing out-of-pocket costs of medical care had less of an impact than providing more money to hospitals. The study also suggests that health ...
Combat troops must minimize the humanness of their enemies in order to kill them. They can't be effective fighters if they're distracted by feelings of empathy for opponents. But indifference to the enemy, rather than loathing, may help prevent war crimes and provide troops with a better path back to healthy civilian lives, researchers at Case Western Reserve University propose.
Their hypothesis is based on new work showing how the brain operates when people objectify—that is, think of others as mere objects — or dehumanize, which entails seeing others as disgusting animals.
These ...
