TY - JOUR
T1 - HELIOS
T2 - AN OPEN-SOURCE, GPU-ACCELERATED RADIATIVE TRANSFER CODE for SELF-CONSISTENT EXOPLANETARY ATMOSPHERES
AU - Malik, Matej
AU - Grosheintz, Luc
AU - Mendonça, João M.
AU - Grimm, Simon L.
AU - Lavie, Baptiste
AU - Kitzmann, Daniel
AU - Tsai, Shang Min
AU - Burrows, Adam S.
AU - Kreidberg, Laura
AU - Bedell, Megan
AU - Bean, Jacob L.
AU - Stevenson, Kevin B.
AU - Heng, Kevin
PY - 2017/2
Y1 - 2017/2
N2 - We present the open-source radiative transfer code named HELIOS, which is constructed for studying exoplanetary atmospheres. In its initial version, the model atmospheres of HELIOS are one-dimensional and plane-parallel, and the equation of radiative transfer is solved in the two-stream approximation with nonisotropic scattering. A small set of the main infrared absorbers is employed, computed with the opacity calculator HELIOS-K and combined using a correlated-k approximation. The molecular abundances originate from validated analytical formulae for equilibrium chemistry. We compare HELIOS with the work of Miller-Ricci & Fortney using a model of GJ 1214b, and perform several tests, where we find: model atmospheres with single-temperature layers struggle to converge to radiative equilibrium; k-distribution tables constructed with cm-1 resolution in the opacity function ( points per wavenumber bin) may result in errors %-10% in the synthetic spectra; and a diffusivity factor of 2 approximates well the exact radiative transfer solution in the limit of pure absorption. We construct "null-hypothesis" models (chemical equilibrium, radiative equilibrium, and solar elemental abundances) for six hot Jupiters. We find that the dayside emission spectra of HD 189733b and WASP-43b are consistent with the null hypothesis, while the latter consistently underpredicts the observed fluxes of WASP-8b, WASP-12b, WASP-14b, and WASP-33b. We demonstrate that our results are somewhat insensitive to the choice of stellar models (blackbody, Kurucz, or PHOENIX) and metallicity, but are strongly affected by higher carbon-to-oxygen ratios. The code is publicly available as part of the Exoclimes Simulation Platform (exoclime.net).
AB - We present the open-source radiative transfer code named HELIOS, which is constructed for studying exoplanetary atmospheres. In its initial version, the model atmospheres of HELIOS are one-dimensional and plane-parallel, and the equation of radiative transfer is solved in the two-stream approximation with nonisotropic scattering. A small set of the main infrared absorbers is employed, computed with the opacity calculator HELIOS-K and combined using a correlated-k approximation. The molecular abundances originate from validated analytical formulae for equilibrium chemistry. We compare HELIOS with the work of Miller-Ricci & Fortney using a model of GJ 1214b, and perform several tests, where we find: model atmospheres with single-temperature layers struggle to converge to radiative equilibrium; k-distribution tables constructed with cm-1 resolution in the opacity function ( points per wavenumber bin) may result in errors %-10% in the synthetic spectra; and a diffusivity factor of 2 approximates well the exact radiative transfer solution in the limit of pure absorption. We construct "null-hypothesis" models (chemical equilibrium, radiative equilibrium, and solar elemental abundances) for six hot Jupiters. We find that the dayside emission spectra of HD 189733b and WASP-43b are consistent with the null hypothesis, while the latter consistently underpredicts the observed fluxes of WASP-8b, WASP-12b, WASP-14b, and WASP-33b. We demonstrate that our results are somewhat insensitive to the choice of stellar models (blackbody, Kurucz, or PHOENIX) and metallicity, but are strongly affected by higher carbon-to-oxygen ratios. The code is publicly available as part of the Exoclimes Simulation Platform (exoclime.net).
KW - methods: numerical
KW - planets and satellites: atmospheres
KW - radiative transfer
UR - http://www.scopus.com/inward/record.url?scp=85012044114&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85012044114&partnerID=8YFLogxK
U2 - 10.3847/1538-3881/153/2/56
DO - 10.3847/1538-3881/153/2/56
M3 - Article
AN - SCOPUS:85012044114
VL - 153
JO - Astronomical Journal
JF - Astronomical Journal
SN - 0004-6256
IS - 2
M1 - 56
ER -