Show simple item record

dc.contributor.authorMoses, J. I.en
dc.contributor.authorMarley, M. S.en
dc.contributor.authorZahnle, K.en
dc.contributor.authorLine, M. R.en
dc.contributor.authorFortney, J. J.en
dc.contributor.authorBarman, T. S.en
dc.contributor.authorVisscher, C.en
dc.contributor.authorLewis, N. K.en
dc.contributor.authorWolff, M. J.en
dc.date.accessioned2017-01-12T23:36:24Z
dc.date.available2017-01-12T23:36:24Z
dc.date.issued2016-09-23
dc.identifier.citationON THE COMPOSITION OF YOUNG, DIRECTLY IMAGED GIANT PLANETS 2016, 829 (2):66 The Astrophysical Journalen
dc.identifier.issn1538-4357
dc.identifier.doi10.3847/0004-637X/829/2/66
dc.identifier.urihttp://hdl.handle.net/10150/621961
dc.description.abstractThe past decade has seen significant progress on the direct detection and characterization of young, self-luminous giant planets at wide orbital separations from their host stars. Some of these planets show evidence for disequilibrium processes like transport-induced quenching in their atmospheres; photochemistry may also be important, despite the large orbital distances. These disequilibrium chemical processes can alter the expected composition, spectral behavior, thermal structure, and cooling history of the planets, and can potentially confuse determinations of bulk elemental ratios, which provide important insights into planet-formation mechanisms. Using a thermo/photochemical kinetics and transport model, we investigate the extent to which disequilibrium chemistry affects the composition and spectra of directly imaged giant exoplanets. Results for specific "young Jupiters" such as HR 8799 b and 51 Eri b are presented, as are general trends as a function of planetary effective temperature, surface gravity, incident ultraviolet flux, and strength of deep atmospheric convection. We find that quenching is very important on young Jupiters, leading to CO/CH4 and N-2/NH3 ratios much greater than, and H2O mixing ratios a factor of a few less than, chemical-equilibrium predictions. Photochemistry can also be important on such planets, with CO2 and HCN being key photochemical products. Carbon dioxide becomes a major constituent when stratospheric temperatures are low and recycling of water via the H-2 + OH reaction becomes kinetically stifled. Young Jupiters with effective temperatures less than or similar to 700 K are in a particularly interesting photochemical regime that differs from both transiting hot Jupiters and our own solar-system giant planets.
dc.description.sponsorshipNational Aeronautics and Space Administration through NASA Exoplanet Research Program [NNX15AN82G, NNX16AC64G]en
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/0004-637X/829/i=2/a=66?key=crossref.c86fa1819c260e738dcbbc15ffcbbfd4en
dc.rights© 2016. The American Astronomical Society. All rights reserved.en
dc.subjectplanetary systemsen
dc.subjectplanets and satellites: atmospheresen
dc.subjectplanets and satellites: compositionen
dc.subjectplanets and satellites: gaseous planetsen
dc.subjectplanets and satellites: individual (51 Eri b, HR 8799 b)en
dc.titleON THE COMPOSITION OF YOUNG, DIRECTLY IMAGED GIANT PLANETSen
dc.typeArticleen
dc.contributor.departmentUniv Arizona, Lunar & Planetary Laben
dc.identifier.journalThe Astrophysical Journalen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal published versionen
refterms.dateFOA2018-06-27T00:30:26Z
html.description.abstractThe past decade has seen significant progress on the direct detection and characterization of young, self-luminous giant planets at wide orbital separations from their host stars. Some of these planets show evidence for disequilibrium processes like transport-induced quenching in their atmospheres; photochemistry may also be important, despite the large orbital distances. These disequilibrium chemical processes can alter the expected composition, spectral behavior, thermal structure, and cooling history of the planets, and can potentially confuse determinations of bulk elemental ratios, which provide important insights into planet-formation mechanisms. Using a thermo/photochemical kinetics and transport model, we investigate the extent to which disequilibrium chemistry affects the composition and spectra of directly imaged giant exoplanets. Results for specific "young Jupiters" such as HR 8799 b and 51 Eri b are presented, as are general trends as a function of planetary effective temperature, surface gravity, incident ultraviolet flux, and strength of deep atmospheric convection. We find that quenching is very important on young Jupiters, leading to CO/CH4 and N-2/NH3 ratios much greater than, and H2O mixing ratios a factor of a few less than, chemical-equilibrium predictions. Photochemistry can also be important on such planets, with CO2 and HCN being key photochemical products. Carbon dioxide becomes a major constituent when stratospheric temperatures are low and recycling of water via the H-2 + OH reaction becomes kinetically stifled. Young Jupiters with effective temperatures less than or similar to 700 K are in a particularly interesting photochemical regime that differs from both transiting hot Jupiters and our own solar-system giant planets.


Files in this item

Thumbnail
Name:
Moses_2016_ApJ_829_66.pdf
Size:
2.994Mb
Format:
PDF
Description:
FInal Published Version

This item appears in the following Collection(s)

Show simple item record