Detection of Fe I and Fe II in the atmosphere of MASCARA-2b using a cross-correlation method

DOI: 
10.1051/0004-6361/202037541
Publication date: 
01/06/2020
Main author: 
Stangret, M.
IAA authors: 
Sánchez-López, A.;López-Puertas, M.
Authors: 
Stangret, M.;Casasayas-Barris, N.;Pallé, E.;Yan, F.;Sánchez-López, A.;López-Puertas, M.
Journal: 
Astronomy and Astrophysics
Refereed: 
Yes
Publication type: 
Article
Volume: 
638
Pages: 
A26
Abstract: 
Ultra-hot Jupiters are gas giants planets whose dayside temperature is greater than 2200 K as a consequence of the strong irradiation received from the host star. These kinds of objects are perfect laboratories to study the chemistry of exoplanetary upper atmospheres via transmission spectroscopy. Exo-atmospheric absorption features are buried in the noise of the in-transit residual spectra. However we can retrieve information of hundreds of atmospheric absorption lines by performing a cross-correlation with an atmospheric transmission model, which allows us to greatly increase the exo-atmospheric signal. The Rossiter-McLaughlin effect and centre-to-limb variation contribute strongly at the high spectral resolution of our data. We present the first detection of Fe I and confirmation of absorption features of Fe II in the atmosphere of the ultra-hot Jupiter MASCARA-2b/KELT-20b, by using three transit observations with HARPS-N. After combining all transit observations we find a high cross-correlation signal of Fe I and Fe II with signal-to-noise ratios of 10.5 ± 0.4 and 8.6 ± 0.5, respectively. The peak absorption for both species appear to be blue-shifted with velocities of - 6.3 ± 0.8 km s<SUP>-1</SUP> for Fe I and - 2.8 ± 0.8 km s<SUP>-1</SUP> for Fe II, suggesting the presence of winds from the day- to night-side of the atmosphere of the planet. These results confirm previous studies of this planet and add a new atomic species (Fe I) to the long list of detected species in the atmosphere of MASCARA-2b, making it, together with KELT-9b, the most feature-rich ultra-hot Jupiter to date.
Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2020A&A...638A..26S/abstract
ADS Bibcode: 
2020A&A...638A..26S
Keywords: 
planetary systems;planets and satellites: individual: MASCARA2-b;planets and satellites: atmospheres;techniques: spectroscopic;Astrophysics - Earth and Planetary Astrophysics;Astrophysics - Instrumentation and Methods for Astrophysics;Astrophysics - Solar and Stellar Astrophysics