The full FUV-MAMA spectrum of HIP94235 b is shown in the image above. The out-of-transit spectrum obtained from orbits 1, 3, 4, and 5 from both visits is shown in black, while the in-transit spectrum from orbit 2 is plotted in pink, using data from both visit 1 and visit 2. 2. Ly-α model and intrinsic Ly-α profile, generated using the lyapy package (Youngblood et al. 2016), plotted in blue and navy (dashed), respectively. The shaded areas represent the blue and red wings, and the corresponding velocity fields. – astro-ph.EP
HIP94235 b, a 120 Myr old companion of Neptune, offers a unique opportunity to study mass loss at a key stage in the system’s evolution: the end of a 100 million year (Myr) old phase of intense XUV radiation.
We present two observations of HIP94235 b with the Hubble Space Telescope’s Space Telescope Imaging Spectrograph (HST/STIS) in the Ly-alpha wavelength region. In the blue and red wings of the Ly-alpha line profile, we observe no differences between inward and outward transport, and detect no significant emission of neutral hydrogen around the planet.
We constrain the rate of neutral hydrogen outflow from HIP94235 b to an upper limit of 10^13 g/s, which is consistent with energy-constrained model predictions of 10^11 g/s. There is no Ly-alpha detection due to the very short photolysis time scale of neutral hydrogen escaping from the planet’s atmosphere.
This time scale, approximately 15 minutes, is significantly shorter than other planets with STIS observations. With energy-constrained mass-loss models, we expect HIP94235 b to become a super-Earth within a time scale of 1 Gyr.
Ava Morrissey, George Cho, Chelsea X. Huang, Duncan Wright, Caitlin Auger, Keighley E. Rockcliffe, Elizabeth R. Newton, James G. Rogers, Neil Gibson, Natalia Lawson, Laura C. Mayorga, Robert A. Wittenmeier
Comments: Accepted for publication in AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Citation: arXiv:2408.02170 [astro-ph.EP] (or arXiv:2408.02170v1 [astro-ph.EP] for this version)
Submission history
Posted by: Ava Morrissey
[v1] Mon, 5 Aug 2024 00:19:55 UTC (6,677 KB)
https://arxiv.org/abs/2408.02170
astronomy,