ALMA makes gas flows visible on the planet formation

Astronomers using the Atacama Large Millimeter / submillimeter Array (ALMA) for the first time to directly observe how extensive gas streams overcome a gap in the disk of matter around a young star. In theory, should such gas streams arise during the growth phase of planets? This is a key stage in the birth of the gas giants. The observations are the second January 2013 published in the journal Nature.

ESO-News, 02/01/2013

An international team of astronomers studied the young star HD 142527, which is about 450 light-years away from Earth and is surrounded by a disk of cosmic gas and dust - the remnants of the cloud from which it arose. The dust disk is divided by a gap in an inner and an outer part. The gap was probably produced by gas formation located in the planet during its orbit around the star clean out their surroundings. The inner region of the disc ranges from star to a distance, which corresponds in our solar system orbit of Saturn, while the outer part of the disc only in the 14-times the distance further out begins. The outer region surrounding the star is not uniform, but has the shape of a horseshoe, probably came through the influence of the gravity of the gas giant about.

"Astronomers had calculated that there should be such gas streams, but we were the first who could watch them really directly," said Simon Casassus of the Universidad de Chile, who led the study. "With ALMA, we are able to bring light into the darkness of the planet formation and to test the theories by observation."

ALMA Casassus and his team used to study the gas and dust around the star. Here they were able to see more details in the immediate vicinity of the star as it with telescopes of this type has ever been possible before. The ALMA observations at submillimetre wavelengths are also not affected as in the infrared or visible light by the bright lights of the star. Although the gap in the disk of dust was previously known, but the scientists discovered diffuse gas remaining in the gap and two dense gas flows from the outer portion of the disk, the flow through the gap in the inner part.

The observations also help in answering another question about the disk around HD 142527th Because the star itself is still in the development phase and is constantly material withdrawn from the inner part of the disc, this would have disintegrated long ago, if there was no process that feeds their new material. Astronomers have found that the rate at which the passing of the gas flows into the inner planet wheel is the right place to replace the loss due to the growth of the star.

First time, diffuse gas was discovered in the gap. "Astronomers have long been looking for this gas, but so far there was only indirect evidence for its existence. With ALMA, we can now see it "directly adds Gerrit van der Plas, another member of the team from the University of Chile.

"A second star in the system would have freed the gap from any residual gas. By determining the amount of leftover gas we were able to narrow down the masses of the objects, the "clean out the gap, adds Perez.

But where are the planet itself? Casassus says he is not surprised that the research team could not be observed directly. "We were looking at the most modern infrared instruments at other telescopes on the planet. We suspect, however, that they are buried very deep in the nearly opaque gas streams. The chances of being able to observe them directly are therefore likely to be very small. "

Through detailed studies of the gas streams and the diffuse gas, astronomers but wish to find out more about the planet. ALMA is under construction and has not yet reached its full potential. If the telescope network is completed, its resolution will be even greater. New observations of the currents will enable researchers then perhaps to determine the exact nature of the planet, such as their masses.

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The presented research results appear in the second January 2013. Titled "flow of gas through a protoplanetary gap" in the journal Nature

The Atacama Large Millimeter / submillimeter Array (ALMA) is an international astronomy facility, which is jointly support by Europe, North America and East Asia in cooperation with the Republic of Chile. From the European side, ALMA is funded by the European Southern Observatory (ESO), in North America by the National Science Foundation (NSF) of the United States in cooperation with the Canadian National Research Council (NRC) and the Taiwan National Science Council (NSC), and in East Asia by the Japanese National Institutes of Natural Sciences (nins) in cooperation with the Academia Sinica (AS) in Taiwan. The development, construction and operation of the ESO are responsible for the European contribution, the National Radio Astronomy Observatory (NRAO), which in turn is operated by Associated Universities, Inc. (AUI), for the North American Post and the National Astronomical Observatory of Japan the East Asian contribution. The Joint ALMA Observatory (JAO) is responsible for the overall project management for the construction, commissioning and operation of ALMA Observatory.

The ESO (European Southern Observatory) is the leading European organization for astronomical research and the most productive astronomical observatory in the world. It is supported by its 15 member countries. Belgium, Brazil, Denmark, Germany, Finland, France, Italy, the Netherlands, Austria, Portugal, Spain, Sweden, Switzerland, the Czech Republic and the United Kingdom The ESO allows astronomers to research by designing powerful ground-based telescopes, construction and operation. Also in promoting international cooperation in the field of astronomy, the organization plays a major role. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope (VLT), the world's astronomical observatory in the range of visible light and two telescopes for sky surveys: VISTA, the largest survey telescope in the world works in the infrared, while the VLT Survey Telescope (VST ) for heaven designed to exclusively in the visible light. ESO is the European partner for the construction of the telescope ALMA, the largest astronomical project in existence. Currently being developed by ESO telescope with a large diameter of 39 meters for observations in the visible and infrared light, which will be once the largest optical telescope in the world: the European Extremely Large Telescope (E-ELT).

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