PDS 70


PDS 70 is a low-mass T Tauri star in the constellation Centaurus. Located approximately 370 light-years from Earth, it has a mass of, and is approximately 10 million years old. The star has a protoplanetary disk containing two nascent exoplanets, named PDS 70b and PDS 70c, which have been directly imaged by the European Southern Observatory's Very Large Telescope. PDS 70b was the first confirmed protoplanet to be directly imaged.

Protoplanetary disk

The protoplanetary disk around PDS 70 was first hypothesized in 1992 and confirmed in 2006 along with a jet-like structure. The disk has a radius of approximately. In 2012 a large gap in the disk was discovered, which was thought to be caused by planetary formation.
The gap was later found to have multiple regions: large dust grains were absent out to 80 au, while small dust grains were only absent out to the previously-observed. There is an asymmetry in the overall shape of the gap; these factors indicate that there are likely multiple planets affecting the shape of the gap and the dust distribution.
In results published in 2018, a planet in the disk, named PDS 70b, was imaged by the Very Large Telescope. With a mass estimated to be a few times greater than Jupiter, the planet is thought to have a temperature of around and an atmosphere with clouds; its orbit has an approximate radius of, taking around 120 years for a revolution. Modelling predicts that the planet has acquired its own accretion disk. The accretion disk was observationally confirmed in 2019, and accretion rate was measured to be at least 5*10−7 Jupiter masses per year.
A second planet, named PDS 70c, was discovered in 2019 using the VLT's MUSE integral field spectrograph. The planet orbits its host star at a distance of, further away than PDS 70b. PDS 70c is in a near 1:2 orbital resonance with PDS 70b, meaning that PDS 70c completes nearly one revolution once every time PDS 70b completes nearly two.

Circumplanetary disk

In July 2019 astronomers using the Atacama Large Millimeter Array reported the first-ever detection of a moon-forming circumplanetary disk. The disk was detected around PDS 70c, with a potential disk observed around PDS 70b. The disk was confirmed by Caltech-led researchers using the W. M. Keck Observatory in Mauna Kea, whose research was published in May 2020.