J/A+A/586/A75 Simulations of hot gas planets atmospheres (Salz+, 2016)
Simulating the escaping atmospheres of hot gas planets in the solar
neighborhood.
Salz M., Czesla S., Schneider P.C., Schmitt J.H.M.M.
<Astron. Astrophys. 586, A75 (2016)>
=2016A&A...586A..75S 2016A&A...586A..75S (SIMBAD/NED BibCode)
ADC_Keywords: Models, atmosphere ; Stars, double and multiple ; Planets
Keywords: methods: numerical - hydrodynamics - radiation mechanisms: general -
planets and satellites: atmospheres -
planets and satellites: dynamical evolution and stability
Abstract:
Absorption of high-energy radiation in planetary thermospheres is
generally believed to lead to the formation of planetary winds. The
resulting mass-loss rates can affect the evolution, particularly of
small gas planets. We present 1D, spherically symmetric hydrodynamic
simulations of the escaping atmospheres of 18 hot gas planets in the
solar neighborhood. Our sample only includes strongly irradiated
planets, whose expanded atmospheres may be detectable via transit
spectroscopy using current instrumentation. The simulations were
performed with the PLUTO-CLOUDY interface, which couples a detailed
photoionization and plasma simulation code with a general MHD code. We
study the thermospheric escape and derive improved estimates for the
planetary mass-loss rates. Our simulations reproduce the
temperature-pressure profile measured via sodium D absorption in
HD 189733 b, but show still unexplained differences in the case of
HD 209458 b. In contrast to general assumptions, we find that the
gravitationally more tightly bound thermospheres of massive and
compact planets, such as HAT-P-2 b are hydrodynamically stable.
Compact planets dispose of the radiative energy input through hydrogen
Ly alpha and free-free emission. Radiative cooling is also important
in HD 189733 b, but it decreases toward smaller planets like GJ 436 b.
Computing the planetary Ly alpha absorption and emission signals from
the simulations, we find that the strong and cool winds of smaller
planets mainly cause strong Ly alpha absorption but little emission.
Compact and massive planets with hot, stable thermospheres cause small
absorption signals but are strong Lyα emitters, possibly
detectable with the current instrumentation. The absorption and
emission signals provide a possible distinction between these two
classes of thermospheres in hot gas planets. According to our results,
WASP-80 and GJ 3470 are currently the most promising targets for
observational follow-up aimed at detecting atmospheric Lyα
absorption signals.
Description:
The following tables contain the simulation results from the
publication. Each table contains a 1D spherically symmetric,
hydrodynamically escaping thermosphere of a hot gas planet. The
atmospheres contain hydrogen and helium, and no molecules. The
simulations were performed with the PLUTO-CLOUDY interface (Salz et
al., Cat. J/A+A/576/A21). Each table contains a header, which
specifies the system parameters, that where used for the simulations.
The simulation region extends to 12/15 planetary radii, but the
atmospheres are only approximately valid up to the Roche-lobe height,
above which the spherical approximation is invalid. The Roche-lobe
height is also given in the header. In the cases of WASP-10 b and
WASP-8 b the atmospheres are hydrodynamically stable and the
atmospheres extend only up to the exobase defined for proton-proton
scattering as given in the publication.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 51 16 List of planet with simulated atmosphere
55cncb.dat 205 490 Simulated atmosphere of 55 Cnc b
corot2b.dat 205 490 Simulated atmosphere of CoRoT-2 b
gj1214b.dat 205 490 Simulated atmosphere of GJ 1214 b
gj3470b.dat 205 490 Simulated atmosphere of GJ 3470 b
gj436b.dat 205 490 Simulated atmosphere of GJ 436 b
hatp11b.dat 205 490 Simulated atmosphere of GJ HAT-P-11 b
hd149026.dat 205 490 Simulated atmosphere of HD 149026 b
hd189733.dat 205 490 Simulated atmosphere of HD 189733 b
hd209458.dat 205 490 Simulated atmosphere of HD 209458 b
hd97658b.dat 205 490 Simulated atmosphere of HD 97658 b
wasp10b.dat 205 321 Simulated atmosphere of WASP-10 b
wasp12b.dat 205 490 Simulated atmosphere of WASP-12 b
wasp43b.dat 205 490 Simulated atmosphere of WASP-43 b
wasp77b.dat 205 490 Simulated atmosphere of WASP-77 b
wasp80b.dat 205 490 Simulated atmosphere of WASP-80 b
wasp8b.dat 205 375 Simulated atmosphere of WASP-8 b
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See also:
J/A+A/576/A21 : The PLUTO CLOUDY Interface (TPCI) (Salz+, 2015)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Simbad Right ascension (J2000)
4- 5 I2 min RAm Simbad Right ascension (J2000)
7- 11 F5.2 s RAs Simbad Right ascension (J2000)
13 A1 --- DE- Simbad Declination sign (J2000)
14- 15 I2 deg DEd Simbad Declination (J2000)
17- 18 I2 arcmin DEm Simbad Declination (J2000)
20- 23 F4.1 arcsec DEs Simbad Declination (J2000)
25- 38 A14 --- Name Planet name
40- 51 A12 --- FileName Name of the file with simulated atmosphere
parameters
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Byte-by-byte Description of file (# headlines):*.dat
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Bytes Format Units Label Explanations
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1- 13 E13.6 --- R Radius in planetary radii
17- 29 E13.6 g/cm3 rho Mass density
33- 45 E13.6 km/s v Velocity
49- 61 E13.6 dyn/cm2 p Pressure
65- 77 E13.6 K T Temperature
81- 93 E13.6 --- mu Mean molecular weight
97-109 E13.6 erg/cm3/s GR Net radiative-heating
113-125 E13.6 --- heatfrac Heating fraction
129-141 E13.6 --- Hfrac H fraction (mixing ratio)
145-157 E13.6 --- H+frac H+ fraction (mixing ratio)
161-173 E13.6 --- Hefrac He fraction (mixing ratio)
177-189 E13.6 --- He+frac He+ fraction (mixing ratio)
193-205 E13.6 --- He++frac He++ fraction (mixing ratio)
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Acknowledgements:
Michael Salz, msalz(at)hs.uni-hamburg.de
(End) Michael Salz [Hamburg], Patricia Vannier [CDS] 30-Nov-2015