TY - JOUR
T1 - Retrieval of planetary and stellar properties in transmission spectroscopy with AURA
AU - Pinhas, Arazi
AU - Rackham, Benjamin V.
AU - Madhusudhan, Nikku
AU - Apai, Dániel
N1 - Funding Information:
AP is grateful for research funding from the Gates Cambridge Trust. AP thanks Siddharth Gandhi for contributing components of the retrieval code used in this work. AP acknowledges Ryan MacDonald for contributing aspects of the plotting routines. BVR acknowledges support from the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1143953. NM acknowledges support from the Science and Technology Facilities Council (STFC), UK. We thank Joanna Barstow and an anonymous reviewer for helping to improve the clarity of the manuscript. The results reported herein benefited from collaborations and/or information exchange within NASA's Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA's Science Mission Directorate. We thank the contributors of the PYTHON Software Foundation and NASA's Astrophysics Data System.
Funding Information:
AP is grateful for research funding from the Gates Cambridge Trust. AP thanks Siddharth Gandhi for contributing components of the retrieval code used in this work. AP acknowledges Ryan MacDonald for contributing aspects of the plotting routines. BVR acknowledges support from the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1143953. NM acknowledges support from the Science and Technology Facilities Council (STFC), UK. We thank Joanna Barstow and an anonymous reviewer for helping to improve the clarity of the manuscript. The results reported herein benefited from collaborations and/or information exchange within NASA’s Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA’s Science Mission Directorate. We thank the contributors of the PYTHON Software Foundation and NASA’s Astrophysics Data System.
Publisher Copyright:
© 2018 The Author(s).
PY - 2018
Y1 - 2018
N2 - Transmission spectroscopy provides a powerful probe of the atmospheric properties of transiting exoplanets. To date, studies of exoplanets in transit have focused on inferring their atmospheric properties such as chemical compositions, cloud/haze properties, and temperature structures. However, surface inhomogeneities in the host stars of exoplanets in the form of cool spots and hot faculae can in principle imprint signatures on the observed planetary transit spectrum. Here we present AURA, a new retrieval paradigm for inferring both planetary and stellar properties from a transmission spectrum. We apply our retrieval framework to a sample of hot giant exoplanets to determine the significance of stellar heterogeneity and clouds/hazes in their spectra. The retrieval analyses distinguish four groups of planets. First, the spectra of WASP-6b and WASP-39b are best characterized by imprints of stellar heterogeneity and hazes and/or clouds. HD209458b and HAT-P-12b comprise the second group for which there is weak evidence for stellar heterogeneity and a high significance of hazes and/or clouds. The third group constitutes HAT-P-1b andWASP-31b and shows weak evidence against stellar heterogeneity but weak to substantial indications of clouds/hazes. The fourth group -WASP-19b, WASP-17b, and WASP-12b - is fit best by molecular and alkali absorbers with H2 scattering without evidence for stellar heterogeneity and weak to no evidence for clouds/hazes. Our retrieval methodology paves the way to simultaneous information on the star and planet from higher resolution spectra using future facilities such as the James Webb Space Telescope and large ground-based facilities.
AB - Transmission spectroscopy provides a powerful probe of the atmospheric properties of transiting exoplanets. To date, studies of exoplanets in transit have focused on inferring their atmospheric properties such as chemical compositions, cloud/haze properties, and temperature structures. However, surface inhomogeneities in the host stars of exoplanets in the form of cool spots and hot faculae can in principle imprint signatures on the observed planetary transit spectrum. Here we present AURA, a new retrieval paradigm for inferring both planetary and stellar properties from a transmission spectrum. We apply our retrieval framework to a sample of hot giant exoplanets to determine the significance of stellar heterogeneity and clouds/hazes in their spectra. The retrieval analyses distinguish four groups of planets. First, the spectra of WASP-6b and WASP-39b are best characterized by imprints of stellar heterogeneity and hazes and/or clouds. HD209458b and HAT-P-12b comprise the second group for which there is weak evidence for stellar heterogeneity and a high significance of hazes and/or clouds. The third group constitutes HAT-P-1b andWASP-31b and shows weak evidence against stellar heterogeneity but weak to substantial indications of clouds/hazes. The fourth group -WASP-19b, WASP-17b, and WASP-12b - is fit best by molecular and alkali absorbers with H2 scattering without evidence for stellar heterogeneity and weak to no evidence for clouds/hazes. Our retrieval methodology paves the way to simultaneous information on the star and planet from higher resolution spectra using future facilities such as the James Webb Space Telescope and large ground-based facilities.
KW - Planets and satellites: atmospheres
KW - Planets and satellites: composition
KW - Scattering
KW - Stars: activity
KW - Starspots
UR - http://www.scopus.com/inward/record.url?scp=85055170147&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85055170147&partnerID=8YFLogxK
U2 - 10.1093/MNRAS/STY2209
DO - 10.1093/MNRAS/STY2209
M3 - Article
AN - SCOPUS:85055170147
SN - 0035-8711
VL - 480
SP - 5314
EP - 5331
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -