Free Astronomy Magazine September-October 2021

SEPTEMBER-OCTOBER 2021 T he sky around the faint orange dwarf star PDS 70 (center of image). The bright blue star in the upper right is χ Centauri. [ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin] observations have now allowed as- tronomers to gain further insights into the system. In addition to con- firming the detection of the circum- planetary disc around PDS 70c and studying its size and mass, they found that PDS 70b does not show clear evidence of such a disc, indicat- ing that it was starved of dust mate- rial from its birth environment by PDS 70c. An even deeper under- standing of the planetary system will be achieved with ESO’s Extremely Large Telescope (ELT), currently un- der construction on Cerro Arma- zones in the Chilean Atacama desert. “The ELT will be key for this research since, with its much higher resolu- tion, we will be able to map the system in great detail,” says co-author Richard Teague, a re- searcher at the Center for Astrophysics | Harvard & Smithsonian, USA. In particular, by using the ELT’s Mid-infrared ELT Imager and Spectro- graph (METIS), the team will be able to look at the gas motions surrounding PDS 70c to get a full 3D picture of the system. U sing ALMA, a team of astronomers have un- ambiguously detected a moon-forming disc around a distant planet for the first time. The planet is a Jupiter-like gas giant, hosted in a system still in the process of being formed. The result prom- ises to shed new light on how moons and planets form in young stellar sys- tems. This video sum- marises the discovery. [ESO] tronomy in Germany and one of the co-authors of the study. “This system therefore offers us a unique oppor- tunity to observe and study the processes of planet and satellite for- mation,” Facchini adds. PDS 70b and PDS 70c, the two planets making up the system, were first discovered using ESO’s Very Large Telescope (VLT) in 2018 and 2019 respectively, and their unique nature means they have been observed with other tele- scopes and instruments many times since. The latest high resolution ALMA where, and how planets and moons form,” explains ESO Research Fellow Stefano Facchini, also involved in the research. “More than 4000 exoplanets have been found until now, but all of them were detected in mature sys- tems. PDS 70b and PDS 70c, which form a system reminiscent of the Jupiter-Saturn pair, are the only two exoplanets detected so far that are still in the process of being formed,” explains Miriam Keppler, researcher at the Max Planck Institute for As- !