Hawaii: how planets are born

17.08.2004

17.08.2004


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Fellow of the Institute of Astronomy, University of Hawaii Michael Lew first got pictures of circumstellar disk of gas and dust from the red dwarf, which are visible on the structure, which can be newly arisen planets.

Dr. Liu worked at Keck-2 telescope with a mirror diameter of ten-(the telescope, as well as his twin Keck-1, are the largest astronomical instrument capable of photographing the sky at infrared wavelengths). The purpose of the observations was the dim star AU Microscopium (AU Microscope), distant from our sun is only 33 light-years.

This red dwarf star with a mass less than half solar, space standards for extremely young — he was only 12 million years old.

In February of this year, a group of U.S. astronomers led by Paul Kalas of the University of California at Berkeley (it was part of himself Lew) found that the star is surrounded by a disc-cloud of dust and gas. AU Microscopium became just the fourth in a row with a star identified by gas and dust disk-companion, and besides, while it is much closer to the Earth than its three predecessors. It is no surprise that she immediately aroused great interest among astronomers.

This interest is justified. According to modern cosmological models, stars are formed in the process of gravitational contraction and warm clouds of cosmic matter. Unused in the process of star dust and gas are not scattered in space, and continue to rotate around a young star. As a result they lose speed collision and are adhered to each other.

This process leads to the formation of planetesimals, dense bodies with a diameter of a few hundred meters to several kilometers, which under favorable conditions, become the nuclei of the terrestrial planets. On the other hand, growing at a rate of planetesimals can accumulate around the volatiles, gradually giving rise to gas-giant planets. The discovery of gas and dust clouds covering the star AU Microscopium, immediately suggested that it occurs precisely those processes of condensation of gas and dust, which may cause the planets.

Now, this theory has gained considerable support as a result of new work by Michael Lew. He made a series of photographs of the neighborhood AU Microscopium, in which the star was screened by an opaque disk (a device that allows you to do these kinds of pictures, called the coronagraph). Photos made with very high resolution — just four hundredths of a second of arc, one five hundred thousandth part of the angular diameter of the full moon. This resolution allows us to distinguish objects with a diameter of about 60 million kilometers, or 0.4 astronomical units (1 AU — the average distance from the Earth to the Sun — is 150 million km).

The pictures noticeable thickening of the disk material, which are removed from the star at a distance of between 25 and 40 astronomical units (in the solar system in this belt are Neptune, and Pluto). Dr. Liu believes that the issue of condensation presence of young planets with a diameter not less than a thousand kilometers.

Battery News, 16.08.2004 8:48
Source: MIGnews

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