LRG-BEASTS: sodium absorption and Rayleigh scattering in the atmosphere of WASP-94A b using NTT/EFOSC2

Abstract

We present an optical transmission spectrum for WASP-94A b, the first atmospheric characterisation of this highly-inflated hot Jupiter. The planet has a reported radius of $1.72_{-0.05}^{+0.06}$ R${}_{\text{Jup}}$, a mass of only $0.456_{-0.036}^{+0.032}$ M${}_{\text{Jup}}$, and an equilibrium temperature of $1508\pm 75$ K. We observed the planet transit spectroscopically with the EFOSC2 instrument on the ESO New Technology Telescope (NTT) at La Silla, Chile: the first use of NTT/EFOSC2 for transmission spectroscopy. We achieved an average transit-depth precision of $128$ ppm for bin widths of $\sim 200$ Angstrom. This high precision was achieved in part by linking Gaussian Process hyperparameters across all wavelength bins. The resulting transmission spectrum, spanning a wavelength range of $3800-7140$ Angstrom, exhibits a sodium absorption with a significance of $4.9\sigma$, suggesting a relatively cloud-free atmosphere. The sodium signal may be broadened, with a best fitting width of $78_{-32}^{+67}$ Angstrom in contrast to the instrumental resolution of $27.2\pm 0.2$ Angstrom. We also detect a steep slope in the blue end of the transmission spectrum, indicating the presence of Rayleigh scattering in the atmosphere of WASP-94A b. Retrieval models show evidence for the observed slope to be super-Rayleigh and potential causes are discussed. Finally, we find narrow absorption cores in the CaII H&K lines of WASP-94A, suggesting the star is enshrouded in gas escaping the hot Jupiter.

16 pages, 15 figures, 6 tables, accepted for publication in MNRAS

References in corpus (46)

• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• PolyChord: nested sampling for cosmology
• Sodium Absorption From the Exoplanetary Atmosphere of HD189733b Detected in the Optical Transmission Spectrum
• Atmospheric Retrieval for Super-Earths: Uniquely Constraining the Atmospheric Composition with Transmission Spectroscopy
• A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b
• Rayleigh scattering in the transit spectrum of HD 189733b
• Water Vapor in the Spectrum of the Extrasolar Planet HD 189733b: 1. the Transit
• Ground-based detection of sodium in the transmission spectrum of exoplanet HD209458b
• An ultrahot gas-giant exoplanet with a stratosphere
• HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering
• HAT-P-26b: A Neptune-Mass Exoplanet with a Well Constrained Heavy Element Abundance
• A consistent retrieval analysis of 10 Hot Jupiters observed in transmission
• Six transiting planets and a chain of Laplace resonances in TOI-178
• The Complete transmission spectrum of WASP-39b with a precise water constraint
• ACCESS I: An Optical Transmission Spectrum of GJ 1214b Reveals a Heterogeneous Stellar Photosphere
• The Transit Light Source Effect II: The Impact of Stellar Heterogeneity on Transmission Spectra of Planets Orbiting Broadly Sun-like Stars
• Trends in Atmospheric Properties of Neptune-Size Exoplanets
• HST hot-Jupiter transmission spectral survey: Haze in the atmosphere of WASP-6b
• VLT FORS2 comparative transmission spectroscopy: Detection of Na in the atmosphere of WASP-39b from the ground
• PLATON II: New Capabilities And A Comprehensive Retrieval on HD 189733b Transit and Eclipse Data
• A Cloudiness Index for Transiting Exoplanets Based on the Sodium and Potassium Lines: Tentative Evidence for Hotter Atmospheres Being Less Cloudy at Visible Wavelengths
• Statistical Analysis of Hubble/WFC3 Transit Spectroscopy of Extrasolar Planets
• New Avenues for Thermal Inversions in hot Jupiters
• The atmosphere of HD 209458b seen with ESPRESSO. No detectable planetary absorptions at high resolution
• ACCESS & LRG-BEASTS: a precise new optical transmission spectrum of the ultrahot Jupiter WASP-103b
• Super-Rayleigh Slopes in Transmission Spectra of Exoplanets Generated by Photochemical Haze
• WASP-94 A and B planets: hot-Jupiter cousins in a twin-star system
• Transmission spectroscopy of the inflated exoplanet WASP-52b, and evidence for a bright region on the stellar surface
• LRG-BEASTS III: Ground-based transmission spectrum of the gas giant orbiting the cool dwarf WASP-80
• Near-Infrared Emission Spectrum of WASP-103b using Hubble Space Telescope/Wide Field Camera 3
• The GAPS Programme at TNG XXVII. Reassessment of a young planetary system with HARPS-N: is the hot Jupiter V830 Tau b really there?
• Ground-Based Transmission Spectroscopy with FORS2: A featureless optical transmission spectrum and detection of H${}_2$O for the ultra-hot Jupiter WASP-103b
• ACCESS: A Visual to Near-infrared Spectrum of the Hot Jupiter WASP-43b with Evidence of ${\mathrm{H}}_2\mathrm{O}$, but no evidence of Na or K
• Detection of Na in WASP-21b's lower and upper atmosphere
• The HARPS search for southern extra-solar planets XLV. Two Neptune mass planets orbiting HD 13808: a study of stellar activity modelling's impact on planet detection
• ACCESS: Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b
• The Hubble PanCET Program: A Metal-rich Atmosphere for the Inflated Hot Jupiter HAT-P-41b
• Evidence of a Clear Atmosphere for WASP-62b: the Only Known Transiting Gas Giant in the JWST Continuous Viewing Zone
• LRG-BEASTS: Ground-based Detection of Sodium and a Steep Optical Slope in the Atmosphere of the Highly Inflated Hot-Saturn WASP-21b
• An enhanced slope in the transmission spectrum of the hot Jupiter WASP-104b
• Dispersed Matter Planet Project Discoveries of Ablating Planets Orbiting Nearby Bright Stars
• Global Analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey
• Obliquity measurement and atmospheric characterization of the WASP-74 planetary system
• Transmission spectroscopy with VLT FORS2: a featureless spectrum for the low-density transiting exoplanet WASP-88b
• ACCESS: An optical transmission spectrum of the high-gravity, hot Jupiter HAT-P-23b

Cited by in corpus (20)

• JWST transmission spectroscopy of HD 209458b: a super-solar metallicity, a very low C/O, and no evidence of CH4, HCN, or C2H2
• Observability of signatures of transport-induced chemistry in clear atmospheres of hot gas giant exoplanets
• Escaping Helium and a Highly Muted Spectrum Suggest a Metal-Enriched Atmosphere on Sub-Neptune GJ3090b from JWST Transit Spectroscopy
• ACCESS: Confirmation of a Clear Atmosphere for WASP-96b and a Comparison of Light Curve Detrending Techniques
• Tracing the formation and migration history: molecular signatures in the atmosphere of misaligned hot Jupiter WASP-94Ab using JWST NIRSpec/G395H
• Detection of Na and K in the atmosphere of the hot Jupiter HAT-P-1b with P200/DBSP
• A precise blue-optical transmission spectrum from the ground: Evidence for haze in the atmosphere of WASP-74b
• Tentative detection of titanium oxide in the atmosphere of WASP-69 b with a 4m ground-based telescope
• LRG-BEASTS: Evidence for clouds in the transmission spectrum of HATS-46 b
• The study on transiting systems HAT-P-13, HAT-P-16 and WASP-32 through combining ground-based and TESS photometry
• How do wavelength correlations affect transmission spectra? Application of a new fast and flexible 2D Gaussian process framework to transiting exoplanet spectroscopy
• The Similar Seven: A set of very-alike exoplanets to test correlations between system parameters and atmospheric properties
• Detection of Na in the atmosphere of the hot Jupiter HAT-P-55b
• Ground-Based Reconnaissance Observations of 21 Exoplanet Atmospheres with the Exoplanet Transmission Spectroscopy Imager
• Rapid characterization of exoplanet atmospheres with the Exoplanet Transmission Spectroscopy Imager (ETSI)
• gallifrey: JAX-based Gaussian process structure learning for astronomical time series
• SPECtrophotometer for TRansmission spectroscopy of exoplanets (SPECTR)
• Low-resolution Transit Spectroscopy of Three Hot Jupiters Using the 2m Himalayan Chandra Telescope
• Using chromatic covariance to correct for scintillation noise in ground-based spectrophotometry
• Impact of Variable Photospheric Radius on Exoplanet Atmospheric Retrievals