![]() ![]() "We only have about 15 examples, and we think this new 'dynamically informed' approach made possible by the Keck II telescope and NIRC2 adaptive optics imaging will be much more efficient compared to blind surveys which have been carried out for the past two decades." "Imaging planets is challenging," Franson said. AF Lep b is about 10,000 times fainter than its host star and is located about eight times the Earth-sun distance. To directly image the planet, the UT Austin team used Keck Observatory's adaptive optics system, which corrects for fluctuations caused by turbulence in Earth's atmosphere, paired with the Keck II Telescope's Near-Infrared Camera 2 (NIRC2) Vector Vortex Coronagraph, which suppresses light from the host star so the planet could be seen more clearly. Franson and Bowler identified the star AF Leporis as one that might harbor a planet, given the way it had moved during 25 years of observations from the Hipparcos and Gaia satellites. Astrometry uses this shift in a star's position on the sky relative to other stars to infer the existence of orbiting planets. Credit: Brendan Bowler, University of Texas at AustinÄespite having a much smaller mass than its host star, an orbiting planet causes a star's position to wobble slightly around the center of mass of the planetary system. The newly imaged planet, AF Lep b (yellow star), has a mass and orbit that make it one of the most Jupiter-like extrasolar planets imaged so far. ![]() Astronomers have confirmed the masses of five (marked with stars) and estimated the rest (dots). This chart shows the masses and orbital distances of all the extrasolar planets that have been directly imaged so far. "This opens the door to using this approach as a new tool for exoplanet discovery." "This is the first time this method has been used to find a giant planet orbiting a young analog of the sun," said Brendan Bowler, an assistant professor of astronomy at UT Austin and senior author on the study. They took a series of deep images of the planet starting in December 2021 two other teams also captured images of the same planet since then. The direct images Franson's team captured revealed that AF Lep b is about three times the mass of Jupiter and orbits AF Leporis, a young sun-like star about 87.5 light-years away. ![]() "When we processed the observations using the Keck II telescope in real time to carefully remove the glare of the star, the planet immediately popped out and became increasingly apparent the longer we observed," said Franson. The study, led by astronomy graduate student Kyle Franson at the University of Texas at Austin (UT Austin), is published in The Astrophysical Journal Letters. The planet, called AF Lep b, is among the first ever discovered using a technique called astrometry this method measures the subtle movements of a host star over many years to help astronomers determine whether hard-to-see orbiting companions, including planets, are gravitationally tugging at it. ![]()
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