Detection of faculae in the transit and transmission spectrum of WASP-69b

Abstract

Context: Transmission spectroscopy is a powerful tool for understanding exoplanet atmospheres. At optical wavelengths, it makes it possible to infer the composition and the presence of aerosols in the atmosphere. However, unocculted stellar activity can result in contamination of atmospheric transmission spectra by introducing spurious slopes and molecular signals. Aims: We aim to characterise the atmosphere of the transiting exoplanet WASP-69b, a hot Jupiter orbiting an active K star, and characterise the host star's activity levels. Methods: We obtained three nights of spectrophotometric data with the FORS2 instrument on the VLT, covering a wavelength range of 340-1100 nm. We performed retrievals on the full spectrum with combined stellar activity and planet atmosphere models. Results: We directly detect a facula in the form of a hot spot crossing event in one of the transits and indirectly detect unocculted faculae through an apparently decreasing radius towards the blue end of the transmission spectrum. We determine a facula temperature of $\Delta T=+644_{-263}^{+427}$ K for the former and a stellar coverage fraction of around 30% with a temperature of $\Delta T=+231\pm 72$ K for the latter. The planetary atmosphere is best fit with a high-altitude cloud deck at 1.4 mbar that mutes atomic and molecular features. We find indications of water and ammonia with $log(H_{2}O)=-2.01_{-0.86}^{+0.54}$ and $log(N{H}_3)=-3.4_{-5.20}^{+0.96}respectivelyandplace3$σ$upperlimitsonTiO($10^{-7.65}$)andK($10^{-7}$). Conclusions. The simultaneous multi-wavelength observations allow us to break the size-contrast degeneracy for facula-crossings, meaning we can obtain temperatures for both the directly and indirectly detected faculae, which are consistent with each other.

arXiv commentAccepted in A\&A, 18 pages, 10 figures

References in corpus (76)

• Analytic Lightcurves for Planetary Transit Searches
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• Multimodal nested sampling: an efficient and robust alternative to MCMC methods for astronomical data analysis
• Cosmic-Ray Rejection by Laplacian Edge Detection
• Detection of an Extrasolar Planet Atmosphere
• A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion
• Efficient, uninformative sampling of limb darkening coefficients for two-parameter laws
• ExoMol molecular line lists XXX: a complete high-accuracy line list for water
• Infrared Transmission Spectroscopy of the Exoplanets HD209458b and XO-1b Using the Wide Field Camera-3 on the Hubble Space Telescope
• Detection of atmospheric haze on an extrasolar planet: The 0.55 - 1.05 micron transmission spectrum of HD189733b with the Hubble Space Telescope
• The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations
• Rayleigh scattering in the transit spectrum of HD 189733b
• The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets
• A population study of gaseous exoplanets
• The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b
• Water Vapor in the Spectrum of the Extrasolar Planet HD 189733b: 1. the Transit
• A Gaussian process framework for modelling instrumental systematics: application to transmission spectroscopy
• ExoMol Molecular linelists -- XXXIII. The spectrum of Titanium Oxide
• Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b
• Limb darkening and exoplanets: testing stellar model atmospheres and identifying biases in transit parameters
• Rotation periods of 12 000 main-sequence Kepler stars: Dependence on stellar spectral type and comparison with v sin i observations
• Aerosol Composition of Hot Giant Exoplanets Dominated by Silicates and Hydrocarbon Hazes
• HELIOS-K: An Ultrafast, Open-source Opacity Calculator for Radiative Transfer
• Detection of titanium oxide in the atmosphere of a hot Jupiter
• High Tide or Riptide on the Cosmic Shoreline? A Water-Rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ~486b from JWST Observations
• ACCESS I: An Optical Transmission Spectrum of GJ 1214b Reveals a Heterogeneous Stellar Photosphere
• A Kepler Study of Starspot Lifetimes with Respect to Light Curve Amplitude and Spectral Type
• An absolute sodium abundance for a cloud-free 'hot Saturn' exoplanet
• How stellar activity affects the size estimates of extrasolar planets
• Retrieval analysis of 38 WFC3 transmission spectra and resolution of the normalisation degeneracy
• HELIOS-K 2.0 Opacity Calculator and Open-source Opacity Database for Exoplanetary Atmospheres
• Three sub-Jupiter-mass planets: WASP-69b & WASP-84b transit active K dwarfs and WASP-70Ab transits the evolved primary of a G4+K3 binary
• New study of the line profiles of sodium perturbed by H2
• The thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8 microns
• WASP-42 b and WASP-49 b: two new transiting sub-Jupiters
• Impact of occultations of stellar active regions on transmission spectra: Can occultation of a plage mimic the signature of a blue sky?
• Using Star Spots to Measure the Spin-orbit Alignment of Transiting Planets
• VLT FORS2 comparative transmission spectroscopy: Detection of Na in the atmosphere of WASP-39b from the ground
• Detection of sodium in the atmosphere of WASP-69b
• Helios-r2 -- A new Bayesian, open-source retrieval model for brown dwarfs and exoplanet atmospheres
• Long Term Photometric Variability in Kepler Full Frame Images: Magnetic Cycles of Sun-Like Stars
• Reliable inference of exoplanet light curve parameters using deterministic and stochastic systematics models
• The GAPS programme at TNG XXII. The GIARPS view of the extended helium atmosphere of HD189733 b accounting for stellar activity
• ACCESS & LRG-BEASTS: a precise new optical transmission spectrum of the ultrahot Jupiter WASP-103b
• SOAP-T: A tool to study the light-curve and radial velocity of a system with a transiting planet and a rotating spotted star
• Properties of solar plage from a spatially coupled inversion of Hinode SP data
• FORS2 observes a multi-epoch transmission spectrum of the hot Saturn-mass exoplanet WASP-49b
• Constraints on Metastable Helium in the Atmospheres of WASP-69b and WASP-52b with Ultra-Narrowband Photometry
• HATS-2b: A transiting extrasolar planet orbiting a K-type star showing starspot activity
• Transmission spectroscopy of the inflated exoplanet WASP-52b, and evidence for a bright region on the stellar surface
• Signs of strong Na and K absorption in the transmission spectrum of WASP-103b
• The GAPS Programme at TNG XXXVIII. Five molecules in the atmosphere of the warm giant planet WASP-69b detected at high spectral resolution
• TOI-222: a single-transit TESS candidate revealed to be a 34-day eclipsing binary with CORALIE, EulerCam and NGTS
• Detection of Na, K and H${}_2$O in the hazy atmosphere of WASP-6b
• Starspot occultations in infrared transit spectroscopy: the case of WASP-52b
• How do starspots influence the transit timing variations of exoplanets? Simulations of individual and consecutive transits
• The GTC exoplanet transit spectroscopy survey XI. Possible detection of Rayleigh scattering in the atmosphere of the Saturn-mass planet WASP-69b
• Inference of the chromospheric magnetic field configuration of solar plage using the Ca II 8542 Å line
• $\text{PyTranSpot}$ - A tool for multiband light curve modeling of planetary transits and stellar spots
• Multiple Clues for Dayside Aerosols and Temperature Gradients in WASP-69 b from a Panchromatic JWST Emission Spectrum
• High-Resolution Transit Spectroscopy of Warm Saturns
• New rotation period measurements of 67,163 Kepler stars
• Probing the atmosphere of WASP-69 b with low- and high-resolution transmission spectroscopy
• Investigating Trends in Atmospheric Compositions of Cool Gas Giant Planets Using Spitzer Secondary Eclipses
• Scrutinizing the relationship between plage areas and sunspot areas and numbers
• A comparison between solar plage and network properties
• ALMA and IRIS Observations of the Solar Chromosphere I: an On-Disk Type II Spicule
• Detection of Aerosols at Microbar Pressures in an Exoplanet Atmosphere
• SAGE: A tool to constrain impacts of stellar activity on transmission spectroscopy
• Characterization of chromospheric activity based on Sun-as-a-star spectral and disk-resolved activity indices
• Transmission spectroscopy with VLT FORS2: a featureless spectrum for the low-density transiting exoplanet WASP-88b
• Evidence for stellar contamination in the transmission spectra of HAT-P-12b
• Ground-Based Transmission Spectroscopy with VLT FORS2: Evidence for faculae and clouds in the optical spectrum of the warm Saturn WASP-110b
• Tentative detection of titanium oxide in the atmosphere of WASP-69 b with a 4m ground-based telescope
• How do wavelength correlations affect transmission spectra? Application of a new fast and flexible 2D Gaussian process framework to transiting exoplanet spectroscopy
• Modeling of Chromospheric Features and Dynamics in Solar Plage

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• A Comprehensive Analysis of the Panchromatic Transmission Spectrum of the Hot-Saturn WASP-96 b: Nondetection of Haze, Possible Sodium Limb Asymmetry, Stellar Characterization, and Formation History
• Where does the simplified Stellar Contamination Model fail in Exoplanet Transmission Spectroscopy?
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