Probing the atmosphere of WASP-69 b with low- and high-resolution transmission spectroscopy

We report detections of atomic species in the atmosphere of MASCARA-2 b, using the first transit observations obtained with the newly commissioned EXPRES spectrograph. EXPRES is a highly stabilized optical echelle spectrograph, designed to detect stellar reflex motions with amplitudes down to 30 cm s−1, and has recently been deployed at the Lowell Discovery Telescope. By analyzing the transmission spectrum of the ultra-hot Jupiter MASCARA-2 b using the cross-correlation method, we confirm previous detections of Fe I, Fe II, and Na I, which likely originate in the upper regions of the inflated atmosphere. In addition, we report significant detections of Mg I and Cr II. The absorption strengths change slightly with time, possibly indicating different temperatures and chemistry in the day- and nightside terminators. Using the effective stellar line-shape variation induced by the transiting planet, we constrain the projected spin-orbit misalignment of the system to 1.6 ± 3.1 degrees, consistent with an aligned orbit. We demonstrate that EXPRES joins a suite of instruments capable of phase-resolved spectroscopy of exoplanet atmospheres.

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The atmosphere of WASP-76b seen with CARMENES: looking for CaII IRT and HeI

10.5194/epsc2021-622 ◽

2021 ◽

Author(s):

Núria Casasayas-Barris ◽

Jaume Orell-Miquel ◽

Monika Stangret ◽

Lisa Nortmann ◽

Fei Yan ◽

...

Keyword(s):

High Resolution ◽

Transmission Spectrum ◽

Potential Candidate ◽

Hot Jupiters ◽

Transmission Spectroscopy ◽

Follow Up Studies ◽

Ionised Calcium

Currently, one of the most used techniques to study the atmosphere of the exoplanets is transmission spectroscopy by means of high-resolution facilities (R > 105). This methodology has led to the detection of several species in the atmosphere of exoplanets, showing that ultra-hot Jupiters (Teq > 2000 K) are one of the most intriguing exoplanets, possessing the richest atmospheres measured to date. Here, using two transit observations with the high-resolution spectrograph CARMENES, we study the atmosphere of one of the most famous ultra-hot Jupiters: WASP-76b. We take advantage of the redder wavelength coverage of CARMENES, in comparison with the facilities used in previous studies of this same planet, and focus our analysis on the CaII IRT triplet at 850nm and the metastable HeI triplet at 1083nm. In line with recent studies, we detect ionised calcium in the atmosphere of WASP-76b and, additionally, find possible evidence of HeI. We contextualise our findings with previous atmospheric studies of other ultra-hot Jupiters and, in particular, with those showing the presence of CaII and HeI absorption in their transmission spectrum. We show that this planet is a potential candidate for further follow up studies of the HeI lines using high-resolution spectrographs located at larger telescopes, such as CRIRES+.

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ESPRESSO high-resolution transmission spectroscopy of WASP-76 b

Astronomy and Astrophysics ◽

10.1051/0004-6361/202039511 ◽

2020 ◽

Cited By ~ 2

Author(s):

H. M. Tabernero ◽

M. R. Zapatero Osorio ◽

R. Allart ◽

F. Borsa ◽

N. Casasayas-Barris ◽

...

Keyword(s):

High Resolution ◽

Transmission Spectroscopy

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Assessing telluric correction methods for Na detections with high-resolution exoplanet transmission spectroscopy

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab134 ◽

2021 ◽

Vol 502 (3) ◽

pp. 4392-4404

Author(s):

Adam B Langeveld ◽

Nikku Madhusudhan ◽

Samuel H C Cabot ◽

Simon T Hodgkin

Keyword(s):

High Resolution ◽

Transmission Spectrum ◽

Atmospheric Model ◽

Atmospheric Conditions ◽

Transmission Spectroscopy ◽

Doublet Line ◽

Exoplanetary Atmospheres ◽

Planetary Transmission ◽

Spurious Signals

ABSTRACT Using high-resolution ground-based transmission spectroscopy to probe exoplanetary atmospheres is difficult due to the inherent telluric contamination from absorption in Earth’s atmosphere. A variety of methods have previously been used to remove telluric features in the optical regime and calculate the planetary transmission spectrum. In this paper we present and compare two such methods, specifically focusing on Na detections using high-resolution optical transmission spectra: (1) calculating the telluric absorption empirically based on the airmass and (2) using a model of the Earth’s transmission spectrum. We test these methods on the transmission spectrum of the hot Jupiter HD 189733 b using archival data obtained with the HARPS spectrograph during three transits. Using models for Centre-to-Limb Variation and the Rossiter–McLaughlin effect, spurious signals which are imprinted within the transmission spectrum are reduced. We find that correcting tellurics with an atmospheric model of the Earth is more robust and produces consistent results when applied to data from different nights with changing atmospheric conditions. We confirm the detection of sodium in the atmosphere of HD 189733 b, with doublet line contrasts of $-0.64 \pm 0.07~{{\ \rm per\ cent}}$ (D2) and $-0.53 \pm 0.07~{{\ \rm per\ cent}}$ (D1). The average line contrast corresponds to an effective photosphere in the Na line located around 1.13 Rp. We also confirm an overall blueshift of the line centroids corresponding to net atmospheric eastward winds with a speed of 1.8 ± 1.2 km s−1. Our study highlights the importance of accurate telluric removal for consistent and reliable characterization of exoplanetary atmospheres using high-resolution transmission spectroscopy.

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High-resolution Transmission Spectroscopy of Four Hot Inflated Gas Giant Exoplanets

The Astronomical Journal ◽

10.3847/1538-3881/ab32ec ◽

2019 ◽

Vol 158 (3) ◽

pp. 120 ◽

Cited By ~ 13

Author(s):

Jiří Žák ◽

Petr Kabáth ◽

Henri M. J. Boffin ◽

Valentin D. Ivanov ◽

Marek Skarka

Keyword(s):

High Resolution ◽

Transmission Spectroscopy ◽

Gas Giant

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The atmosphere of WASP-17b: Optical high-resolution transmission spectroscopy

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732029 ◽

2018 ◽

Vol 618 ◽

pp. A98 ◽

Cited By ~ 7

Author(s):

Sara Khalafinejad ◽

Michael Salz ◽

Patricio E. Cubillos ◽

George Zhou ◽

Carolina von Essen ◽

...

Keyword(s):

High Resolution ◽

Light Curve ◽

Physical Properties ◽

Transmission Spectrum ◽

Atmospheric Model ◽

Atmospheric Temperature ◽

Temporal Variations ◽

Light Curves ◽

Sodium Absorption ◽

Transmission Spectroscopy

High-resolution transmission spectroscopy is a method for understanding the chemical and physical properties of upper exoplanetary atmospheres. Due to large absorption cross-sections, resonance lines of atomic sodium D-lines (at 5889.95 and 5895.92 Å) produce large transmission signals. Our aim is to unveil the physical properties of WASP-17b through an accurate measurement of the sodium absorption in the transmission spectrum. We analyze 37 high-resolution spectra observed during a single transit of WASP-17b with the MIKE instrument on the 6.5 m Magellan Telescopes. We exclude stellar flaring activity during the observations by analyzing the temporal variations of Hα and Ca II infrared triplet (IRT) lines. We then obtain the excess absorption light curves in wavelength bands of 0.75, 1, 1.5, and 3 Å around the center of each sodium line (i.e., the light curve approach). We model the effects of differential limb-darkening, and the changing planetary radial velocity on the light curves. We also analyze the sodium absorption directly in the transmission spectrum, which is obtained by dividing in-transit by out-of-transit spectra (i.e., the division approach). We then compare our measurements with a radiative transfer atmospheric model. Our analysis results in a tentative detection of exoplanetary sodium: we measure the width and amplitude of the exoplanetary sodium feature to be σNa = (0.128 ± 0.078) Å and ANa = (1.7 ± 0.9)% in the excess light curve approach and σNa = (0.850 ± 0.034) Å and ANa = (1.3 ± 0.6)% in the division approach. By comparing our measurements with a simple atmospheric model, we retrieve an atmospheric temperature of 15501550 −200+700 K and radius (at 0.1 bar) of 1.81 ± 0.02 RJup for WASP-17b.

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