Free Astronomy Magazine July-August 2021

50 JULY-AUGUST 2021 ASTRO PUBLISHING of planets throughout the entire system. The planet PDS 70b is encircled by its own gas-and-dust disk that’s siphoning material from the vastly larger circumstellar disk. The researchers hypoth- esize that magnetic field lines extend from its circum- planetary disk down to the exoplanet’s atmosphere and are funneling material onto the planet’s surface. “If this material follows columns from the disk onto the planet, it would cause local hot spots,” Zhou ex- plained. “These hot spots could be at least 10 times hotter than the temperature of the planet.” These hot patches were found to glow fiercely in UV light. These observa- tions offer insights into how gas giant planets formed around our Sun 4.6 billion years ago. Jupiter may have bulked up on a surrounding disk of infalling material. Its major moons would have also formed from leftovers in that disk. A challenge to the team was over- coming the glare of the parent star. PDS 70b orbits at approximately the same distance as Uranus does from the Sun, but its star is more than 3,000 times brighter than the planet at UV wavelengths. As Zhou processed the images, he very carefully removed the star’s glare to leave behind only light emit- ted by the planet. In doing so, he improved the limit of how close a planet can be to its star in Hubble observations by a factor of five. “Thirty-one years after launch, we’re still find- ing new ways to use Hubble,” Bowler added. “Yifan’s observing strat- egy and post-processing technique will open new windows into studying similar systems, or even the same system, re- peatedly with Hubble. With future observa- tions, we could poten- tially discover when the majority of the gas and dust falls onto their planets and if it does so at a constant rate.” T he European Southern Ob- servatory’s Very Large Telescope caught the first clear image of a forming planet, PDS 70b, around a dwarf star in 2018. The planet stands out as a bright point to the right of the center of the image, which is blacked out by the coronagraph mask used to block the light of the central star. [ESO, VLT, André B. Müller (ESO)] H ubble observations pinpoint planet PDS 70b. A coronagraph on Hubble’s camera blocks out the glare of the cen- tral star for the planet to be directly observed. Though over 4,000 exo- planets have been cata- loged so far, only about 15 have been directly im- aged to date by tele- scopes. The team’s fresh technique for using Hub- ble to directly image this planet paves a new route for further exoplanet re- search, especially during a planet’s formative years. [NASA, ESA, McDonald Observatory–University of Texas, Yifan Zhou (UT). Image processing: Joseph DePasquale (STScI)] !