Detection of Fe I Emission in the Dayside Spectrum of WASP-33b
Abstract
We analyze the high-resolution emission spectrum of WASP-33b taken using the High Dispersion Spectrograph (R ≈ 165,000) on the 8.2 m Subaru telescope. The data cover λ ≈ 6170-8817 Å, divided over 30 spectral orders. The telluric and stellar lines are removed using a de-trending algorithm, SYSREM, before cross-correlating with planetary spectral templates. We calculate the templates assuming a 1D plane-parallel hydrostatic atmosphere including continuum opacity of bound-free H- and Rayleigh scattering by H2 with a range of constant abundances of Fe I. Using a likelihood-mapping analysis, we detect an Fe I emission signature at 6.4σ located at ${K}_{{\rm{p}}}$ of 226.0 ${}_{-2.3}^{+2.1}$ km s-1 and vsys of -3.2 ${}_{-1.8}^{+2.1}$ km s-1—consistent with the planet's expected velocity in the literature. We also confirm the existence of a thermal inversion in the dayside of the planet, which is very likely to be caused by the presence of Fe I and previously detected TiO in the atmosphere. This makes WASP-33b one of the prime targets to study the relative contributions of both species to the energy budget of an ultra-hot Jupiter. * Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2020
- DOI:
- 10.3847/2041-8213/aba4b6
- arXiv:
- arXiv:2007.05508
- Bibcode:
- 2020ApJ...898L..31N
- Keywords:
-
- Exoplanet atmospheres;
- Exoplanet atmospheric composition;
- High resolution spectroscopy;
- 487;
- 2021;
- 2096;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted for publication on ApJL