2023 Division for Planetary Sciences the American Astronomical Society October 3, 2023 San Antonio, TX A Large and Variable Leading Tail of Helium in HAT-P-67b, a Sub-Saturn Undergoing Runaway Inflation Caroline V. Morley, Jessica Luna, Morgan MacLeod, Antonija Oklopčić, Aishwarya Ganesh, Quang H. Tran, Zhoujian Zhang, Brendan P. Bowler, William D. Cochran, Daniel M. Krolikowski, Suvrath Mahadevan, Joe P. Ninan, Guðmundur Stefánsson, Andrew Vanderburg, Joseph A. Zalesky, Gregory R. Zeimann Gully-Santiago et al. arXiv 2307.08959
8100 – 12,800 Å R = 55,000 Hobby Eberly Telescope (HET), Texas, USA We get abundant orbital phase coverage: Large orbital phase coverage Visits In–Transit Out-of-Transit HAT-P-67 b 7 35
He I 10833 Å from HPF spectra of HAT-P-67 b. The excess absorption preceeds the transit by up to 130 planetary radii in a large leading tail. The prominence of this leading tail is direct evidence for preferential dayside mass loss. We estimate a mass loss rate of 2 x 1013 g/s, and lifetime less than a Gyr. This pattern broadly agrees with theoretical predictions and explains the lack of inflated sub-Saturns. Gully-Santiago et al. arXiv 2307.08959