Evidence of Water Vapor in the Atmosphere of a Metal-rich Hot Saturn with High-resolution Transmission Spectroscopy

DOI: 
10.3847/1538-3881/ad5be9
Publication date: 
12/09/2024
Main author: 
Rafi, Sayyed A.
IAA authors: 
Sánchez-López, Alejandro
Authors: 
Rafi, Sayyed A.;Nugroho, Stevanus K.;Tamura, Motohide;Nortmann, Lisa;Sánchez-López, Alejandro
Journal: 
The Astronomical Journal
Publication type: 
Article
Volume: 
168
Pages: 
106
Abstract: 
Transmission spectroscopy presents one of the most successful approaches for investigating the atmospheres of exoplanets. We analyzed the near-infrared high-resolution transmission spectrum of a hot Saturn, HD 149026 b, taken using CARMENES spectrograph ( ). We found evidence of H<SUB>2</SUB>O at a signal-to-noise ratio (S/N) of ∼4.8. We also performed grid search using a Bayesian framework and constrained the orbital velocity K <SUB>p</SUB> and rest velocity V <SUB>rest</SUB> to km s<SUP>‑1</SUP> and km s<SUP>‑1</SUP>, respectively. While the retrieved K <SUB>p</SUB> value is consistent with theoretical prediction, the retrieved V <SUB>rest</SUB> value is highly redshifted (&gt;3σ). This might be an indication of either anomalous atmospheric dynamics at play or an orbit with nonzero eccentricity. Additionally, we searched for HCN but no successful detection has been made, possibly due to the relatively low-S/N data set. The detection of H<SUB>2</SUB>O and subsequent retrieval of its abundance, coupled with analysis of other species such as CO in the K band, for example, might help us to get some information about the atmospheric C/O ratio and metallicity, which in turn could give us some insight into the planet's formation scenario.
Database: 
ADS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2024AJ....168..106R/abstract
ADS Bibcode: 
2024AJ....168..106R
Keywords: 
Exoplanet atmospheres;Exoplanet atmospheric composition;High resolution spectroscopy;Infrared astronomy;Transmission spectroscopy;487;2021;2096;786;2133;Astrophysics - Earth and Planetary Astrophysics