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Ukrainian Astronomers Spot Five New Exocomets around Beta Pictoris


Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS), a team of astronomers from Ukraine has detected the transits of five comets around Beta Pictoris (β Pictoris), the second brightest star in the constellation of Pictor, about 63 light years away from Earth.

This artist’s conception shows exocomets in a young planetary system. Image credit: NASA / JPL-Caltech.

This artist’s conception shows exocomets in a young planetary system. Image credit: NASA / JPL-Caltech.

Beta Pictoris is an A5-type star with a mass of about 1.8 times the Sun and an age of only 20 million years.

It hosts a circumstellar disk of gas and dust; a large number of comet-like bodies; and two giant planets: Beta Pictoris b and c.

Beta Pictoris b is a gas giant approximately 9 to 13 times the mass of Jupiter. It orbits the parent star once every 22 years at a distance of 9.8 AU (astronomical units).

Beta Pictoris c has a mass of 8.2 times that of Jupiter and is much closer to its star. It orbits at 2.7 AU and has an orbital period of roughly 1,200 days.

“The short-term optical variation of the Beta Pictoris brightness was first reported in 1995,” Dr. Yakiv Pavlenko and his colleagues from the Main Astronomical Observatory of the NAS of Ukraine and the Astronomical Observatory of the Taras Shevchenko National University wrote in their paper.

“To explain the phenomenon, the mechanism of the star’s light scattering by an elongated dust cloud or by a cometary coma passing across the star’s disk was adopted as the most plausible one.”

“Recently, astronomers presented the Beta Pictoris light curve analysis based on the TESS data,” they added.

“They found three transit events interpreted as exocomet passages across the stellar disk of Beta Pictoris.”

“The purpose of our study was to carry out further investigations of the light curves of Beta Pictoris by searching for transit events that can be interpreted as exocomet passages across the star’s disk.”

In the study, the astronomers analyzed the TESS data from the Mikulski Archive for Space Telescopes (MAST).

They found five new distinct dipping events with shapes resembling the expected profiles due to the passage of a exocomet-like body across the star disk.

The orbital distances of the transiting objects were between 0.5 and 1.5 AU.

“These new transits have asymmetric profiles with very shallow flux drop at level of 0.03% and a duration between 0.51 and 2.01 days,” the authors said.

“The newly found transits are very similar in duration and depth to those shallow asymmetric dips (except the last one that is degraded by the spacecraft coarse pointing), which were discovered in 2019.”

“We conclude that the young system of Beta Pictoris shows significant comet activity,” they added.

The team’s paper was published in the journal Astronomy & Astrophysics.

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Ya. Pavlenko et al. 2022. New exocomets of β Pic. A&A 660, A49; doi: 10.1051/0004-6361/202142111



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