Detailed Elemental Abundances of a Super-Neptune Host Star Using High-resolution, Near-infrared Spectroscopy

Hejazi, Neda; Crossfield, Ian J. M.; Nordlander, Thomas; Souto, Diogo; Masseron, Thomas; Marfil, Emilio
Bibliographical reference

American Astronomical Society Meeting Abstracts

Advertised on:
1
2023
Number of authors
6
IAC number of authors
2
Citations
0
Refereed citations
0
Description
We present the first elemental abundance measurements of the K dwarf (K6) exoplanet-host star WASP-107 using high-resolution (R~45,000), near-infrared (H- and K-band) spectra from the IGRINS Spectral Archive. We use the previously determined physical parameters of the star from literature and infer the abundances of 13 elements, i.e., C, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe (with precision < 0.1 dex) based on model fitting using MARCS model atmospheres and the spectral synthesis code Turbospectrum. The orbiting planet, WASP-107b, is a super Neptune with a mass in the Neptune regime (=1.8 MNeptune) and a radius close to Jupiter's (=0.94 RJupiter), which has already been studied in some detail via transits and radial velocity techniques as well as the HST transmission spectra (Kreidberg et al. 2018, Piaulet et al. 2021). Our results show near-solar abundances and a subsolar C/O ratio for the host star, which are consistent with the corresponding values of the planet obtained from the HST spectra. This planet is also a JWST Cycle 1 exoplanet target, which allows atmospheric abundance measurements with high precision (< 0.2 dex for gas-rich planets). This will enable us to compare the planetary and stellar chemical abundances more properly, which is essential in understanding planet formation and dominant mechanisms (e.g., core accretion) as well as the interplay between initial composition and present-day chemistry of planetary system. Our study is a proof-of-concept that will pave the way for such measurements to be made for all (or at least, most) of JWST's cooler exoplanet-host stars.