Atmosphere Expansion and Mass Loss of Close-Orbit Giant Exoplanets Heated by Stellar Xuv. I. Modeling of Hydrodynamic Escape of Upper Atmospheric Material

Шайхисламов, И. Ф.; Khodachenko, M. L.; Sasunov, Yu. L.; Lämmer, H.; Kislyakova, K. G.; Еркаев, Н. В.

doi:10.1088/0004-637x/795/2/132

Cited by 113 publications

(139 citation statements)

References 39 publications

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“…If one applies the hydrodynamic code describing the upper atmosphere and calculating the escape (Erkaev et al 2013) of WASP-12b, one obtains a loss rate of 1.5 × 10 35 particles (hydrogen atoms) per second for the predominantly hydrogen atmosphere. This number is in a very good agreement with other studies for mass-loss rates for close hot Jupiters, e.g., Shaikhislamov et al (2014). If one assumes a Mg solar abundance mix of 10 −4 , this gives an upper limit of 1.5×10 31 magnesium atoms per second.…”

Section: Outgassing From Molten Lava Surfaces: a Source Of Mg And Casupporting

confidence: 90%

On the ultraviolet anomalies of the WASP-12 and HD 189733 systems: Trojan satellites as a plasma source

Kislyakova

Pilat-Lohinger

Funk

et al. 2016

Mon. Not. R. Astron. Soc.

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We suggest an additional possible plasma source to explain part of the phenomena observed for the transiting hot Jupiters WASP-12b and HD 189733b in their ultraviolet (UV) light curves. In the proposed scenario, material outgasses from the molten surface of Trojan satellites on tadpole orbits near the Lagrange points L 4 and L 5 . We show that the temperature at the orbital location of WASP-12b is high enough to melt the surface of rocky bodies and to form shallow lava oceans on them. In case of WASP12b, this leads to the release of elements such as Mg and Ca, which are expected to surround the system. The predicted Mg and Ca outgassing rates from two Io-sized WASP-12b Trojans are ≈ 2.2 × 10 27 s −1 and ≈ 2.2 × 10 26 s −1 , respectively. Trojan outgassing can lead to the apparent lack of emission in Mgii h&k and Caii H&K line cores of WASP-12. For HD 189733b, the mechanism is only marginally possible due to the lower temperature. This may be one of the reasons that couldn't explain the early ingress of HD 189733b observed in the far-UV (FUV) Cii doublet due to absence of carbon within elements outgassed by molten lava. We investigate the long-term stability region of WASP-12b and HD 189733b in case of planar and inclined motion of these satellites and show that unlike the classical exomoons orbiting the planet, Io-sized Trojans can be stable for the whole systems life time.

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Section: Outgassing From Molten Lava Surfaces: a Source Of Mg And Casupporting

confidence: 90%

On the ultraviolet anomalies of the WASP-12 and HD 189733 systems: Trojan satellites as a plasma source

Kislyakova

Pilat-Lohinger

Funk

et al. 2016

Mon. Not. R. Astron. Soc.

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“…To understand the origin of the temperature minima, we look at the effects of H + 3 cooling, X-ray heating, and EUV heating. Shaikhislamov et al (2014) and Chadney et al (2015) who did similar tests for close-in Jupiter-mass planets.…”

Section: Temperature Minimamentioning

confidence: 86%

“…One dimensional models are widely used for exoplanet studies, particularly with respect to upper atmosphere modelling (see e.g. Murray-Clay et al 2009;Shaikhislamov et al 2014;Salz et al 2016;Erkaev et al 2016Erkaev et al , 2017Fossati et al 2017;Lammer et al 2016). An upgrade to 2D or 3D simulations is instead required to model the interaction between the expanding planetary atmosphere with the stellar wind, particularly when considering ion pick-up processes related to planetary atmospheric escape.…”

Section: Possible Impact Of the Modelling Formalismmentioning

confidence: 99%

Young planets under extreme UV irradiation

Kubyshkina

Lendl

Fossati

et al. 2018

A&A

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The K2-33 planetary system hosts one transiting ∼5 R⊕ planet orbiting the young M-type host star. The planet's mass is still unknown, with an estimated upper limit of 5.4 MJ . The extreme youth of the system (<20 Myr) gives the unprecedented opportunity to study the earliest phases of planetary evolution, at a stage when the planet is exposed to an extremely high level of high-energy radiation emitted by the host star. We perform a series of 1D hydrodynamic simulations of the planet's upper atmosphere considering a range of possible planetary masses, from 2 to 40 M⊕, and equilibrium temperatures, from 850 to 1300 K, to account for internal heating as a result of contraction. We obtain temperature profiles mostly controlled by the planet's mass, while the equilibrium temperature has a secondary effect. For planetary masses below 7-10 M⊕, the atmosphere is subject to extremely high escape rates, driven by the planet's weak gravity and high thermal energy, which increase with decreasing mass and/or increasing temperature. For higher masses, the escape is instead driven by the absorption of the high-energy stellar radiation. A rough comparison of the timescales for complete atmospheric escape and age of the system indicates that the planet is more massive than 10 M⊕.

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“…In particular, the absorption of high-energy radiation causes ionizations with subsequent thermalization of the kinetic energy of photoelectrons. The resulting heating initiates a process of continuous thermospheric expansion, thus, launching a planetary wind powered by the stellar high-energy emission (e.g., Yelle 2004;Tian et al 2005;García Muñoz 2007;Penz et al 2008;Murray-Clay et al 2009;Koskinen et al 2013;Shaikhislamov et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Energy-limited escape revised

Salz

Schneider

Czesla

et al. 2015

A&A

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Gas planets in close proximity to their host stars experience photoevaporative mass loss. The energy-limited escape concept is generally used to derive estimates for the planetary mass-loss rates. Our photoionization hydrodynamics simulations of the thermospheres of hot gas planets show that the energy-limited escape concept is valid only for planets with a gravitational potential lower than log 10 (−Φ G ) < 13.11 erg g −1 because in these planets the radiative energy input is efficiently used to drive the planetary wind. Massive and compact planets with log 10 (−Φ G ) 13.6 erg g −1 exhibit more tightly bound atmospheres in which the complete radiative energy input is re-emitted through hydrogen Lyα and free-free emission. These planets therefore host hydrodynamically stable thermospheres. Between these two extremes the strength of the planetary winds rapidly declines as a result of a decreasing heating efficiency. Small planets undergo enhanced evaporation because they host expanded atmospheres that expose a larger surface to the stellar irradiation. We present scaling laws for the heating efficiency and the expansion radius that depend on the gravitational potential and irradiation level of the planet. The resulting revised energy-limited escape concept can be used to derive estimates for the mass-loss rates of super-Earth-sized planets as well as massive hot Jupiters with hydrogen-dominated atmospheres.

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Atmosphere Expansion and Mass Loss of Close-Orbit Giant Exoplanets Heated by Stellar Xuv. I. Modeling of Hydrodynamic Escape of Upper Atmospheric Material

Cited by 113 publications

References 39 publications

On the ultraviolet anomalies of the WASP-12 and HD 189733 systems: Trojan satellites as a plasma source

On the ultraviolet anomalies of the WASP-12 and HD 189733 systems: Trojan satellites as a plasma source

Young planets under extreme UV irradiation

Energy-limited escape revised

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