Massive stars are born the same way as their smaller counterparts

Thursday, July 15, 2010

LONDON - Researchers have managed to obtain the first infrared image of a compact disc closely encircling a massive young star-a strong evidence that massive stars form in the same way as their smaller brothers.

The international research team led by Stefan Kraus with team members from two research groups of the Max Planck Institute for Radio Astronomy in Bonn, made the discovery using a combination of the Very Large Telescope Interferometer, the APEX telescope and the New Technology Telescope.

The team of astronomers looked at an object, known by the cryptic name of IRAS 13481-6124.

About twenty times the mass of our Sun and five times its radius, the young central star, which is still surrounded by a disk, its pre-natal cocoon, is located in the constellation of Centaurus, about 10,000 light-years away.

Disks of gas and dust around young stars are the material reservoir from which also planets can form.

“Our observations show a disc surrounding an embryonic young, massive star, which is now fully formed. One can say that the baby is about to hatch!” Nature quoted Stefan Kraus, who led the study, as saying.

From archival images obtained by the NASA Spitzer Space Telescope as well as from observations done with the APEX 12-meter submillimeter telescope, astronomers discovered the presence of a jet.

“Such jets ejected from young stars, generally indicate the presence of a circumstellar disc,”said Karl Menten.

“Radio telescopes like the APEX sub-mm telescope allow us, for the first time, to study outflows at short radio wavelengths in the submillimeter range. The present project brings together the expertise of two research groups at MPIfR, infrared interferometry in order to investigate the structure of the disk and submillimeter astronomy showing the structure of the bipolar outflow,” he added.

Circumstellar discs are an essential ingredient in the formation process of low-mass stars such as our Sun.

However, it has been proposed that massive stars might form when smaller stars merge.

In order to discover and understand the properties of this disc, astronomers employed ESO’s Very Large Telescope Interferometer (VLTI).

By combining light from three of the VLTI’s 1.8-meter Auxiliary Telescopes with the AMBER instrument, this facility allows astronomers to see details equivalent to those a telescope with a mirror of 85 meters in diameter would see.

The resulting resolution is about 2.4 milliarcseconds, which is equivalent to picking out the head of a screw on the International Space Station.

With this unique capability, complemented by observations done with another of ESO’s telescopes, the 3.58-meter New Technology Telescope at La Silla, the team was able to detect a disc around IRAS 13481-6124.

“This is the first high-resolution image of the inner disk around a young star, and the combination of infrared interferometry and observations at radio wavelengths allows us to study the important physical connection between discs and outflows. The new observations suggest that disks play a similar role in the formation process of both low- and high-mass stars,” said Gerd Weigelt from the infrared interferometry team at MPIfR.

The astronomers conclude that the system is about 60,000 years old, and that the star has reached its final mass.

The disc will soon start to evaporate and eventually form a planetary system.

The flared disc extends to about 130 times the Earth-Sun distance or 130 astronomical units (AU) — and has a mass similar to that of the star, roughly twenty times the Sun.

The study has been published in the latest issue of Nature. (ANI)

Filed under: Science and Technology

will not be displayed