TY - JOUR

T1 - Exoplanet atmospheres at high resolution through a modest-size telescope Fe II in MASCARA-2b and KELT-9b with FIES on the Nordic Optical Telescope

AU - Bello-Arufe, Aaron

AU - Buchhave, Lars A.

AU - Mendonca, Joao M.

AU - Tronsgaard, Rene

AU - Heng, Kevin

AU - Hoeijmakers, H. Jens

AU - Mayo, Andrew W.

PY - 2022/6/15

Y1 - 2022/6/15

N2 - Ground-based, high-resolution spectrographs are providing us with an unprecedented view of the dynamics and chemistry of the atmospheres of planets outside the Solar System. While there are a large number of stable and precise high-resolution spectrographs on modest-size telescopes, it is the spectrographs at observatories with apertures larger than 3.5 m that dominate the atmospheric follow-up of exoplanets. In this work we explore the potential of characterising exoplanetary atmospheres with FIES, a high-resolution spectrograph at the 2.56 m Nordic Optical Telescope. We observed two transits of MASCARA-2 b (also known as KELT-20 b) and one transit of KELT-9 b to search for atomic iron, a species that has recently been discovered in both neutral and ionised forms in the atmospheres of these ultra-hot Jupiters using large telescopes. Using a cross-correlation method, we detect a signal of Fe II at the 4.5 sigma and 4.0 sigma level in the transits of MaSCARA-2 b. We also detect Fe II in the transit of KELT-9 b at the 8.5 sigma level. Although we do not find any significant Doppler shift in the signal of MASCARA-2 b, we do measure a moderate blueshift (3-6 km s(-1)) of the feature in KELT-9 b, which might be a manifestation of high-velocity winds transporting Fe II from the planetary dayside to the nightside. Our work demonstrates the feasibility of investigating exoplanet atmospheres with FIES, and it potentially unlocks a wealth of additional atmosphere detections with this and other high-resolution spectrographs mounted on similar-size telescopes.

AB - Ground-based, high-resolution spectrographs are providing us with an unprecedented view of the dynamics and chemistry of the atmospheres of planets outside the Solar System. While there are a large number of stable and precise high-resolution spectrographs on modest-size telescopes, it is the spectrographs at observatories with apertures larger than 3.5 m that dominate the atmospheric follow-up of exoplanets. In this work we explore the potential of characterising exoplanetary atmospheres with FIES, a high-resolution spectrograph at the 2.56 m Nordic Optical Telescope. We observed two transits of MASCARA-2 b (also known as KELT-20 b) and one transit of KELT-9 b to search for atomic iron, a species that has recently been discovered in both neutral and ionised forms in the atmospheres of these ultra-hot Jupiters using large telescopes. Using a cross-correlation method, we detect a signal of Fe II at the 4.5 sigma and 4.0 sigma level in the transits of MaSCARA-2 b. We also detect Fe II in the transit of KELT-9 b at the 8.5 sigma level. Although we do not find any significant Doppler shift in the signal of MASCARA-2 b, we do measure a moderate blueshift (3-6 km s(-1)) of the feature in KELT-9 b, which might be a manifestation of high-velocity winds transporting Fe II from the planetary dayside to the nightside. Our work demonstrates the feasibility of investigating exoplanet atmospheres with FIES, and it potentially unlocks a wealth of additional atmosphere detections with this and other high-resolution spectrographs mounted on similar-size telescopes.

KW - instrumentation

KW - spectrographs

KW - planets and satellites

KW - atmospheres

KW - gaseous planets

KW - IRON EMISSION-LINES

KW - GAPS PROGRAM

KW - TRANSMISSION SPECTRUM

KW - ORBITAL MOTION

KW - HARPS-N

KW - HOT

KW - SPECTROSCOPY

KW - DAYSIDE

KW - PLANET

KW - TRANSIT

U2 - 10.1051/0004-6361/202142787

DO - 10.1051/0004-6361/202142787

M3 - Journal article

VL - 662

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A51

ER -