Astronomers discover first planet around a young star

January 3rd, 2008 - 2:39 pm ICT by admin  

London, Jan 3 (ANI): Astronomers have discovered the first planet around a star young enough to boast a protoplanetary disc of dust and gas.

Planets are thought to grow as dust collides and sticks together in so-called protoplanetary discs around young stars.

Observations have shown that these discs tend to dissipate within the first 10 million years of a star’s life, suggesting that planets must take shape before that time.

But until now, none of the 270 known extrasolar planets had been found around stars young enough to still have protoplanetary discs. That’s because most planet searches have excluded young stars, whose pulsations can mimic the telltale wobbles caused by potential planets.

Now, a team led by Johny Setiawan of the Max Planck Institute for Astronomy in Heidelberg, Germany, has found the first planet around a star young enough to boast a protoplanetary disc using spectroscopic measurements taken with a 2.2-metre telescope at La Silla Observatory in Chile.

According to a report in the New Scientist, when the researchers carefully observed the star, called TW Hydrae (TW Hya), they found a disturbance in the star’s spectra every 3.56 days that did not correspond to signs of the star’s activity, suggesting the repeating signal was indeed caused by an orbiting planet.

The planet appears to be quite massive, weighing in at nearly 10 Jupiters. It also orbits extremely close to the star 10 times closer than Mercury’s distance from the Sun, within the inner rim of the star’s dusty disc.

The researchers believe the planet formed farther away from the star between the orbits of Earth and Jupiter in our solar system, where there was more material from which it could grow. Then, as it lost energy through gravitational interactions with gas in its natal disc, it moved to its present location over the course of 100,000 years or so, stopping when it reached a region cleared of gas.

The fact that the planet was found around a star estimated to be 10 million years old gives a real upper limit to the timescales of planet formation and migration”, said the researchers.

According to the research, it is still not clear whether a planet as massive as 9.8 Jupiters could have formed through core accumulation or whether gravitational instabilities in the disc must have been involved.

Nonetheless, the new discovery is the ideal system to test computer simulations of the various models, said the researchers. (ANI)

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