A Model of the H$\alpha$ and Na Transmission Spectrum of HD 189733b

Abstract

This paper presents a detailed hydrostatic model of the upper atmosphere of HD 189733b, with the goal of constraining its temperature, particle densities, and radiation field over the pressure range $10^{-4}-10\mu \mathrm{bar}$, where the observed H$\alpha$ transmission spectrum is produced. The atomic hydrogen level population is computed including both collisional and radiative transition rates. The Ly$\alpha$ resonant scattering is computed using a Monte-Carlo simulation. The model transmission spectra are in broad agreement with the data. Excitation of the H(2$\ell$) population is mainly by Ly$\alpha$ radiative excitation due to the large Ly$\alpha$ intensity. The density of H(2$\ell$) is nearly flat over two decades in pressure, and is optically thick to H$\alpha$. Additional models computed for a range of the stellar Lyman continuum (LyC) flux suggest that the variability in H$\alpha$ transit depth may be due to the variability in the stellar LyC. Since metal lines provide the dominant cooling of this part of the atmosphere, the atmosphere structure is sensitive to the density of species such as Mg and Na which may themselves be constrained by observations. Since the H$\alpha$ and Na D lines have comparable absorption depths, we argue that the center of the Na D lines are also formed in the atomic layer where the H$\alpha$ line is formed.

23 pages, 17 figures, 5 tables. Accepted by ApJ

References in corpus (15)

• Atmospheric Escape from Hot Jupiters
• Sodium Absorption From the Exoplanetary Atmosphere of HD189733b Detected in the Optical Transmission Spectrum
• Rayleigh scattering in the transit spectrum of HD 189733b
• Atomic and Molecular Opacities for Brown Dwarf and Giant Planet Atmospheres
• Spectrally resolved detection of sodium in the atmosphere of HD189733b with the HARPS spectrograph
• Stellar activity of planetary host star HD 189733
• Atmospheric escape from HD 189733b observed in HI Lyman-alpha: detailed analysis of HST/STIS September 2011 observations
• Hubble Space Telescope detection of oxygen in the atmosphere of exoplanet HD189733b
• Mg line formation in late-type stellar atmospheres: I. The model atom
• The corona of HD 189733 and its X-ray activity
• The effect of Lyman $\alpha$ radiation on mini-Neptune atmospheres around M stars: application to GJ 436b
• Exoplanetary atmospheric sodium revealed by the orbital motion. Narrow-band transmission spectroscopy of HD 189733b with UVES
• FUV variability of HD 189733. Is the star accreting material from its hot Jupiter?
• A Non-isothermal Theory for Interpreting Sodium Lines in Transmission Spectra of Exoplanets
• Hydrogen Lyman-alpha and Lyman-beta spectral radiance profiles in the quiet Sun

Cited by in corpus (30)

• A spectral survey of an ultra-hot Jupiter: Detection of metals in the transmission spectrum of KELT-9 b
• Mass loss rate and local thermodynamic state of KELT-9 b thermosphere from the hydrogen Balmer series
• Detection of Na, K, and H$\alpha$ absorption in the atmosphere of WASP-52b using ESPRESSO
• Detection of ionized calcium in the atmosphere of the ultra-hot Jupiter KELT-9b
• Sodium and Potassium Signatures of Volcanic Satellites Orbiting Close-in Gas Giant Exoplanets
• Rapid escape of ultra-hot exoplanet atmospheres driven by Hydrogen Balmer absorption
• The GAPS Programme at TNG. XLI. The climate of KELT-9b revealed with a new approach to high spectral resolution phase curves
• The young HD 73583 (TOI-560) planetary system: Two 10-M${}_{\oplus }$ mini-Neptunes transiting a 500-Myr-old, bright, and active K dwarf
• Detection of the hydrogen Balmer lines in the ultra-hot Jupiter WASP-33b
• Alkaline Exospheres of Exoplanet Systems: Evaporative Transmission Spectra
• Time-resolved rotational velocities in the upper atmosphere of WASP-33 b
• GJ 436b and the stellar wind interaction: simulations constraints using Ly$\alpha$ and H$\alpha$ transits
• A hydrodynamic study of the escape of metal species and excited hydrogen from the atmosphere of the hot Jupiter WASP-121b
• Detection of Na in WASP-21b's lower and upper atmosphere
• Global 3D simulation of the upper atmosphere of HD189733b and absorption in metastable HeI and Lyα lines
• Vertical structure of an exoplanet's atmospheric jet stream
• Modeling H$\alpha$ and He 10830 transmission spectrum of WASP-52b
• Transmission spectroscopy of the ultra-hot Jupiter MASCARA-4 b: Disentangling the hydrostatic and exospheric regimes of ultra-hot Jupiters
• Understanding Sun-as-a-star variability of solar Balmer lines
• An efficient Monte Carlo model for the slowing down of photoelectrons. Application to H-$\alpha$ in exoplanet atmospheres
• Atmosphere escape inferred from modelling the H$\alpha$ transmission spectrum of WASP-121b
• Detection of Na and K in the atmosphere of the hot Jupiter HAT-P-1b with P200/DBSP
• Multi-epoch detections of the extended atmosphere and transmission spectra of KELT-9b with a 1.5 m telescope
• Probing the atmosphere of HD189733b with the Na I and K I lines
• The Hubble/STIS Near-ultraviolet Transmission Spectrum of HD 189733b
• Spectral signature of atmospheric winds in high resolution transit observations
• Dust Accretion onto Exoplanets
• A Novel Solution for Resonant Scattering Using Self-Consistent Boundary Conditions
• PEPSI's non-detection of escaping hydrogen and metal lines adds to the enigma of WASP-12 b
• Mass loss by atmospheric escape from extremely close-in planets