A second planet around the star Beta Pictoris

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 August 20, 2019

After the giant planet Beta Pictoris B, discovered in 2009, a "little sister" was spotted around the star.

A new giant planet has been discovered around the young star Beta Pictoris, which shines 63.4 light years from Earth, according to a study published Monday in the journal "Nature Astronomy".

Artist's impression of the planet Beta Pictoris b

"This is a giant planet of about 3000 times the mass of the Earth, located 2.7 times farther from its star than the Earth of the Sun," said Anne-Marie Lagrange, CNRS researcher at the Institute of Planetology and Astrophysics of Grenoble, lead author of the study.

Visible to the naked eye and long known for its rapid rotation, the star Beta Pictoris became famous in the 1980s, when it allowed astronomers to obtain the first image of a disk of dust and gas surrounding a star, vestige of the primitive cloud that gave birth to it.

 Map of the sky Beta Pictoris

In addition, the global system of which it is a part, about 20 million years old - very little compared to the 4.6 billion years of the solar system - could look like what our world should be right after its formation. "This planetary system is probably the best to understand their formation and early evolution," says the astrophysicist who studied for 35 years.

Planets in formation

After the giant planet Beta Pictoris B, discovered by a team of Anne-Marie Lagrange in 2009, a second was spotted around the star. This "little sister, almost twin", logically takes the name of Beta Pictoris C. According to scientists, the two planets are still being formed.

"Giant planets play a crucial role in planetary systems," says the astrophysicist. "We can also study the interactions between the planets and the dust disk".

Dust and gas disc around a solar system in formation

Beta Pictoris C was indirectly detected by the HARPS spectrograph, a planet hunter from the Southern European Observatory (ESO) in Chile. The researchers used the so-called "radial velocity" method, which consists in detecting in the spectrum of a star the disturbances caused by the presence around it of a celestial body.

They also determined that Beta Pictoris C, housed between her star and her older sister, orbits relatively close to Beta Pictoris which she tours in about 1200 days. But according to the study "more data will be needed to obtain more accurate estimates". Other planets could be discovered around Beta Pictoris, but "maybe much less massive," concludes Anne-Marie Lagrange.

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European Southern Observatory (ESO): https://www.eso.org/public/

Images, Text, Credits: ATS/ESO/IAU Sky & Telescope/NASA/Orbiter.ch Aerospace/Roland Berga.

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