NASA’s Transiting Exoplanets Survey Satellite (TESS) has spotted the long tails of extrasolar comets orbiting the very young star beta Pictoris.
This artist’s impression shows exocomets orbiting beta Pictoris. Image credit: L. Calçada / ESO.
Beta Pictoris is one of the brightest stars in the sky and the second brightest star in the constellation Pictor, about 63 light-years away from Earth.
Also known as HD 39060, the star is estimated to be about 23 million years old and is known to host a gas giant, beta Pictoris b.
The star also harbors a warped debris disk composed of dust and gas that could, in time, evolve into a torus of icy bodies much like Solar System’s Kuiper Belt.
The disk is easily seen because it is tilted edge-on and is especially bright due to a very large amount of starlight-scattering dust.
“Because of its close proximity and circumstellar disk, the beta Pictoris system can be considered an ideal test bed to study the formation and evolution of planetary systems, including minor bodies such as exocomets and exomoons,” said Universität Innsbruck astronomer Sebastian Zieba and colleagues.
The researchers analyzed data from TESS and found three transits of short-period exocomets in front of beta Pictoris.
“We use data collected by TESS from October 19, 2018 to February 1, 2019 in Sectors 4 through 7,” they said.
“We identify three distinct dipping events in the light curve of beta Pictoris over a 105-day period. These dips have depths from 0.5 to 2 millimagnitudes and durations of up to 2 days for the largest dip.”
“These dips are asymmetric in nature and are consistent with a model of an evaporating comet with an extended tail crossing the disk of the star.”
The team’s paper was published online in the journal Astronomy & Astrophysics (arXiv.org preprint).
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Sebastian Zieba et al. 2019. A transiting exocomet detected in broadband light by TESS in the β Pictoris system. A&A, in press; arXiv: 1903.11071
