2024AJ....167..214P -
Astron. J., 167, 214 (2024/May-0)
Detection of an Atmospheric Outflow from the Young Hot Saturn TOI-1268b.
PEREZ-GONZALEZ J., GREKLEK-MCKEON M., VISSAPRAGADA S., SAIDEL M., KNUTSON H.A., LINSSEN D. and OKLOPCIC A.
Abstract (from CDS):
Photoevaporative mass-loss rates are expected to be highest when planets are young and the host star is more active, but to date there have been relatively few measurements of mass-loss rates for young gas giant exoplanets. In this study we measure the present-day atmospheric mass-loss rate of TOI-1268b, a young (110-380 Myr) and low density (0.71${}_{-0.13}^{+0.17}$ g cm–3) hot Saturn located near the upper edge of the Neptune desert. We use Palomar/WIRC to search for excess absorption in the 1083 nm helium triplet during two transits of TOI-1268b. We find that it has a larger transit depth (${0.285}_{-0.050}^{+0.048} \% $ excess) in the helium bandpass than in the TESS observations, and convert this excess absorption into a mass-loss rate by modeling the outflow as a Parker wind. Our results indicate that this planet is losing mass at a rate of $\mathrm{log}\dot{M}=10.2\pm 0.3$ g s–1 and has a thermosphere temperature of ${6900}_{-1200}^{+1800}$ K. This corresponds to a predicted atmospheric lifetime much larger than 10 Gyr. Our result suggests that photoevaporation is weak in gas giant exoplanets even at early ages.
Abstract Copyright:
© 2024. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Exoplanet atmospheres - Narrow band photometry
Simbad objects:
12
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