Study Confirms Spotting Baby Planets Around Young Stars

A new observation using the world's most powerful radio observatory of a very young star confirmed it's giving birth to a system of baby exoplanets.

According to Gadgets 360, in November 2014, Atacama Large Millimetre Array (ALMA) in Chile released a surprising image of a young star HL Tauri and its dust disk. It was the sharpest image ever taken for this kind of space object which revealed several gaps in the dust disk around the star. Since the disk is believed to be the site of planet formations, researchers suggested that the dark gaps are carved by infant planets forming the disk that sweep away dust along their orbits.

But, HL Taur is very young, approximated to be only about a million years, and classical studies show that it takes more than tens of millions of years for planets to be able to form from small dust. A few researchers propose other mechanisms to form gaps, such as changes in the dust size through coalescence or destruction; or the formation of dust due to gas molecules freezing.

According to Discovery News, ALMA has revisited the stellar beauty to observe emissions from HCO+ gas molecules, and not from the dust itself. The theory they have come up with is this: if there really are baby planets forming in those dust gaps, the gas distribution in the star's protoplanetary disk should also display a similar pattern of rings. The planetary gravities would suck up dust and gas in equal measure. If baby planets aren't the cause, the HCO+ gas distribution should be uniform with no ring-like features.

If the latter scenario happens, astronomers would be forced to say that the dust gaps were in fact caused by different sized dust grains generating emissions at invisible wave lengths (as seen by ALMA) and the "baby planets" hypothesis would be a flop. However, the gas distribution is as revolutionary as the dust observations, which means that the gaps are being caused by planets in the process of being born.

The ALMA observations saw 2 main disk gaps at 28 and 69 astronomical units (where 1 AU is the average distance from the Earth to the sun) from the star. If these rings surrounded our sun, they'd be at the approximate orbital locations of Neptune (30 AU) and dwarf planet Eris (68 AU), one of the most distant known objects in our solar system.

"To our surprise, these gaps in the gas overlap with the dust gaps," said astronomer Hsi-Wei Yen of Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. "This supports the idea that the gaps are the footprints left by baby planets."

Yen and his team also thinks that to form the inner disk gap, there's enough material there to create a world around 80 percent the mass of Jupiter. The outer gap is a little more mysterious, and more work is needed to understand its structure, but the researchers estimate if there is a planet in the gap, it could form a world twice the mass of Jupiter.