Three infant planets detected around new-born star: studies

Source: Xinhua| 2018-06-13 23:57:32|Editor: Mu Xuequan
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WASHINGTON, June 13 (Xinhua) -- Two independent teams of astronomers have found evidence that three young planets are in orbit around an infant star, according to study published on Wednesday in the journal Astrophysical Journal Letters.

The astronomers identified three discrete disturbances in the gas-filled disk of the star known as HD 163296, which are strongest evidence yet that newly formed planets are in orbit there.

HD 163296 is about 4 million years old and located about 330 light-years from Earth in the direction of the constellation Sagittarius.

"We looked at the localized, small-scale motion of gas in a star's protoplanetary disk. This entirely new approach could uncover some of the youngest planets in our galaxy," said Richard Teague, an astronomer at the University of Michigan and principal author on one of the papers.

Rather than focusing on the dust within the protoplanetary disk, the astronomers studied the distribution and motion of carbon monoxide gas throughout the disk. The protoplanetary disks are the gas- and dust-filled planet factories that encircle young stars.

Molecules of CO naturally emit a very distinctive millimeter-wavelength light and subtle changes in the wavelength of this light could provide a glimpse into the motion of the gas in the disk, according to researchers.

If there were no planets, gas would move around a star in a very simple, predictable pattern known as Keplerian rotation.

"It would take a relatively massive object, like a planet, to create localized disturbances in this otherwise orderly motion," said Christophe Pinte of Monash University in Australia and lead author on one of the two papers.

The team led by Teague identified two distinctive planet-like patterns in the disk, one at approximately 80 astronomical units (AU) from the star and the other at 140 AU.

The other team, led by Pinte, identified the third at about 260 AU from the star. The astronomers calculate that all three planets are similar in mass to Jupiter.

An astronomical unit is the average distance from the Earth to the Sun, or about 150 million kilometers.