Magnetic moment and plasma environment of HD 209458b as determined from Ly$\alpha$ observations

Abstract

Transit observations of HD 209458b in the stellar Lyman-$\alpha$ (Ly$\alpha$) line revealed strong absorption in both blue and red wings of the line interpreted as hydrogen atoms escaping from the planet's exosphere at high velocities. The following sources for the absorption were suggested: acceleration by the stellar radiation pressure, natural spectral line broadening, charge exchange with stellar wind. We reproduce the observation by means of modelling that includes all aforementioned processes. Our results support a stellar wind with a velocity of $\approx 400$ km$\times$s${}^{-1}$ at the time of the observation and a planetary magnetic moment of $\approx 1.6\times 10^{26}$ A$\times$m${}^2$.

This is the author's version of the work. It is posted here by permission of the AAAS for non-commercial research use only. The definitive version was published in Science, vol. 346, p. 981, 21 November 2014, DOI: 10.1126/science.1257829. 3 pages, 3 figures

References in corpus (4)

• Lyman-$\alpha$ Transit Spectroscopy and the Neutral Hydrogen Tail of the Hot Neptune GJ436b
• Energetic neutral atoms as the explanation for the high velocity hydrogen around HD 209458b
• Exoplanet HD209458b: inflated hydrogen atmosphere but no sign of evaporation
• The HARPS search for southern extra-solar planets. XXXI. Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities

Cited by in corpus (49)

• The active lives of stars: a complete description of rotation and XUV evolution of F, G, K, and M dwarfs
• Hubble PanCET: An extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470 b
• New Observational Constraints on the Winds of M Dwarf Stars
• Magnetic field strengths of hot Jupiters from signals of star-planet interactions
• Atmospheric Escape Processes and Planetary Atmospheric Evolution
• The evolution of the solar wind
• Atmosphere Expansion and Mass Loss of Close-Orbit Giant Exoplanets heated by Stellar XUV. II. Effects of Planetary Magnetic Field, Structuring of inner Magnetosphere
• Signatures of Strong Magnetization and Metal-Poor Atmosphere for a Neptune-Size Exoplanet
• Global 3D hydrodynamic modeling of in-transit Lyα absorption of GJ436b
• Re-visit of HST FUV observations of hot-Jupiter system HD 209458: No Si III detection and the need for COS transit observations
• Hydrodynamic escape of water vapor atmospheres near very active stars
• Exoplanets as probes of the winds of host stars: the case of the M dwarf GJ 436
• Two regimes of interaction of a Hot Jupiter's escaping atmosphere with the stellar wind and generation of energized atomic hydrogen corona
• An Overabundance of Low-density Neptune-like Planets
• How Expanded Ionospheres of Hot Jupiters Can Prevent Escape of Radio Emission Generated by the Cyclotron Maser Instability
• The Influence of Coronal Mass Ejections on the Mass-loss Rates of Hot-Jupiters
• Lyα Absorption at Transits of HD 209458b: A Comparative Study of Various Mechanisms Under Different Conditions
• Near-ultraviolet Transmission Spectroscopy of HD 209458b: Evidence of Ionized Iron Beyond the Planetary Roche Lobe
• The JADE code: Coupling secular exoplanetary dynamics and photo-evaporation
• The impact of intrinsic magnetic field on the absorption signatures of elements probing the upper atmosphere of HD209458b
• The fundamentals of Lyman-alpha exoplanet transits
• Airy worlds or barren rocks? On the survivability of secondary atmospheres around the TRAPPIST-1 planets
• On possible types of magnetospheres of hot Jupiters
• The solar wind from a stellar perspective: how do low-resolution data impact the determination of wind properties?
• Using helium 10830 Å transits to constrain planetary magnetic fields
• A multi-wavelength look at the GJ 9827 system -- No evidence of extended atmospheres in GJ 9827 b and d from HST and CARMENES data
• Hydrodynamical interaction of stellar and planetary winds: effects of charge exchange and radiation pressure on the observed Ly$\alpha$ absorption
• Can we detect aurora in exoplanets orbiting M dwarfs?
• Blocking metal accretion onto population III stars by stellar wind
• Ionization and transport in partially ionized multicomponent plasmas: Application to atmospheres of hot Jupiters
• The Influence of Coronal Mass Ejections on the Gas Dynamics of the Atmosphere of a "Hot~Jupiter" Exoplanet
• Transit Ly-$\alpha$ signatures of terrestrial planets in the habitable zones of M dwarfs
• The Detectability of Radio Auroral Emission from Proxima B
• Magnetic induction processes in Hot Jupiters, application to KELT-9b
• Evolution of the Earth's Polar Outflow From Mid-Archean to Present
• On the Fast Magnetic Rotator Regime of Stellar Winds
• The Exosphere as a Boundary: Origin and Evolution of Airless Bodies in the Inner Solar System and Beyond Including Planets with Silicate Atmospheres
• X-ray detection of astrospheres around three main-sequence stars and their mass-loss rates
• Space environment and magnetospheric Poynting fluxes of the exoplanet $\tau$ Boötis b
• Using Lyman-$\alpha$ transits to constrain models of atmospheric escape
• Atmospheric Characterization via Broadband Color Filters on the PLAnetary Transits and Oscillations of stars (PLATO) Mission
• Atmospheric escape in hot Jupiters under sub-Alfvénic interactions
• Using the helium triplet as a tracer of the physics of giant planet outflows
• Star-Planet Interactions: A Computational View
• Stellar wind induced soft X-ray emission from close-in exoplanets
• Effects of Charge Exchange on the Evaporative Wind of HD 209458b
• Migrating Dynamo Waves and Consequences for Stellar Current Sheets
• Connecting Solar and Stellar Flares/CMEs: Expanding Heliophysics to Encompass Exoplanetary Space Weather
• Thermoelastic Contraction as a Suppressor of Atmospheric Escape in Close-in Exoplanets