Observing atmospheric escape in sub-Jovian worlds with JWST
| Title: | Observing atmospheric escape in sub-Jovian worlds with JWST |
|---|---|
| Authors: | Santos, Leonardo A. Dos, Alam, Munazza K., Espinoza, Néstor, Vissapragada, Shreyas |
| Publication Year: | 2023 |
| Collection: | Astrophysics |
| Subject Terms: | Astrophysics - Earth and Planetary Astrophysics |
| More Details: | Hydrodynamic atmospheric escape is considered an important process that shapes the evolution of sub-Jovian exoplanets, particularly those with short orbital periods. The metastable He line in the near-infrared at $1.083$ $\mu$m is a reliable tracer of atmospheric escape in hot exoplanets, with the advantage of being observable from the ground. However, observing escaping He in sub-Jovian planets has remained challenging due to the systematic effects and telluric contamination present in ground-based data. With the successful launch and operations of JWST, we now have access to extremely stable high-precision near-infrared spectrographs in space. Here we predict the observability of metastable He with JWST in two representative and previously well-studied warm Neptunes, GJ 436 b ($T_{\rm eq} = 687~{\rm K}$, $R_{\rm p} = 0.37~{\rm R_J}$) and GJ 1214 b ($T_{\rm eq} = 588~{\rm K}$, $R_{\rm p} = 0.25~{\rm R_J}$). Our simulated JWST observations for GJ 436 b demonstrate that a single transit with NIRSpec/G140H is sensitive to mass loss rates that are two orders of magnitude lower than what is detectable from the ground. Our exercise for GJ 1214 b show that the best configuration to observe the relatively weak outflows of warm Neptunes with JWST is with NIRSpec/G140H, and that NIRSpec/G140M and NIRISS/SOSS are less optimal. Since none of these instrument configurations can spectrally resolve the planetary absorption, we conclude that the 1D isothermal Parker-wind approximation may not be sufficient for interpreting such observations. More sophisticated models are critical for breaking the degeneracy between outflow temperature and mass-loss rate for JWST measurements of metastable He. Comment: 14 pages, 7 figures, under review at AAS Journals; this version follows the first round of revision. Feedback from the community is welcome |
| Document Type: | Working Paper |
| DOI: | 10.3847/1538-3881/accf10 |
| Access URL: | http://arxiv.org/abs/2304.07792 |
| Accession Number: | edsarx.2304.07792 |
| Database: | arXiv |
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