SPITZER SECONDARY ECLIPSE OBSERVATIONS of FIVE COOL GAS GIANT PLANETS and EMPIRICAL TRENDS in COOL PLANET EMISSION SPECTRA

Joshua A. Kammer, Heather A. Knutson, Michael Line, Jonathan J. Fortney, Drake Deming, Adam Burrows, Nicolas B. Cowan, Amaury H M J Triaud, Eric Agol, Jean Michel Desert, Benjamin J. Fulton, Andrew W. Howard, Gregory P. Laughlin, Nikole K. Lewis, Caroline V. Morley, Julianne I. Moses, Adam P. Showman, Kamen O. Todorov

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

In this work we present Spitzer 3.6 and 4.5 μm secondary eclipse observations of five new cool ( K) transiting gas giant planets: HAT-P-19b, WASP-6b, WASP-10b, WASP-39b, and WASP-67b. We compare our measured eclipse depths to the predictions of a suite of atmosphere models and to eclipse depths for planets with previously published observations in order to constrain the temperature- and mass-dependent properties of gas giant planet atmospheres. We find that the dayside emission spectra of planets less massive than Jupiter require models with efficient circulation of energy to the night side and/or increased albedos, while those with masses greater than that of Jupiter are consistently best-matched by models with inefficient circulation and low albedos. At these relatively low temperatures we expect the atmospheric CH4/CO ratio to vary as a function of metallicity, and we therefore use our observations of these planets to constrain their atmospheric metallicities. We find that the most massive planets have dayside emission spectra that are best-matched by solar metallicity atmosphere models, but we are not able to place strong constraints on metallicities of the smaller planets in our sample. Interestingly, we find that the ratio of the 3.6 and 4.5 μm brightness temperatures for these cool transiting planets is independent of planet temperature, and instead exhibits a tentative correlation with planet mass. If this trend can be confirmed, it would suggest that the shape of these planets' emission spectra depends primarily on their masses, consistent with the hypothesis that lower-mass planets are more likely to have metal-rich atmospheres.

Original languageEnglish (US)
Article number118
JournalAstrophysical Journal
Volume810
Issue number2
DOIs
StatePublished - Sep 10 2015
Externally publishedYes

Fingerprint

eclipses
planets
planet
metallicity
gas giant planets
atmospheres
emission spectra
albedo
Jupiter (planet)
atmosphere
Jupiter
brightness temperature
night
gas
trends
temperature

Keywords

  • eclipses
  • planetary systems
  • techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

SPITZER SECONDARY ECLIPSE OBSERVATIONS of FIVE COOL GAS GIANT PLANETS and EMPIRICAL TRENDS in COOL PLANET EMISSION SPECTRA. / Kammer, Joshua A.; Knutson, Heather A.; Line, Michael; Fortney, Jonathan J.; Deming, Drake; Burrows, Adam; Cowan, Nicolas B.; Triaud, Amaury H M J; Agol, Eric; Desert, Jean Michel; Fulton, Benjamin J.; Howard, Andrew W.; Laughlin, Gregory P.; Lewis, Nikole K.; Morley, Caroline V.; Moses, Julianne I.; Showman, Adam P.; Todorov, Kamen O.

In: Astrophysical Journal, Vol. 810, No. 2, 118, 10.09.2015.

Research output: Contribution to journalArticle

Kammer, JA, Knutson, HA, Line, M, Fortney, JJ, Deming, D, Burrows, A, Cowan, NB, Triaud, AHMJ, Agol, E, Desert, JM, Fulton, BJ, Howard, AW, Laughlin, GP, Lewis, NK, Morley, CV, Moses, JI, Showman, AP & Todorov, KO 2015, 'SPITZER SECONDARY ECLIPSE OBSERVATIONS of FIVE COOL GAS GIANT PLANETS and EMPIRICAL TRENDS in COOL PLANET EMISSION SPECTRA', Astrophysical Journal, vol. 810, no. 2, 118. https://doi.org/10.1088/0004-637X/810/2/118
Kammer, Joshua A. ; Knutson, Heather A. ; Line, Michael ; Fortney, Jonathan J. ; Deming, Drake ; Burrows, Adam ; Cowan, Nicolas B. ; Triaud, Amaury H M J ; Agol, Eric ; Desert, Jean Michel ; Fulton, Benjamin J. ; Howard, Andrew W. ; Laughlin, Gregory P. ; Lewis, Nikole K. ; Morley, Caroline V. ; Moses, Julianne I. ; Showman, Adam P. ; Todorov, Kamen O. / SPITZER SECONDARY ECLIPSE OBSERVATIONS of FIVE COOL GAS GIANT PLANETS and EMPIRICAL TRENDS in COOL PLANET EMISSION SPECTRA. In: Astrophysical Journal. 2015 ; Vol. 810, No. 2.
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abstract = "In this work we present Spitzer 3.6 and 4.5 μm secondary eclipse observations of five new cool ( K) transiting gas giant planets: HAT-P-19b, WASP-6b, WASP-10b, WASP-39b, and WASP-67b. We compare our measured eclipse depths to the predictions of a suite of atmosphere models and to eclipse depths for planets with previously published observations in order to constrain the temperature- and mass-dependent properties of gas giant planet atmospheres. We find that the dayside emission spectra of planets less massive than Jupiter require models with efficient circulation of energy to the night side and/or increased albedos, while those with masses greater than that of Jupiter are consistently best-matched by models with inefficient circulation and low albedos. At these relatively low temperatures we expect the atmospheric CH4/CO ratio to vary as a function of metallicity, and we therefore use our observations of these planets to constrain their atmospheric metallicities. We find that the most massive planets have dayside emission spectra that are best-matched by solar metallicity atmosphere models, but we are not able to place strong constraints on metallicities of the smaller planets in our sample. Interestingly, we find that the ratio of the 3.6 and 4.5 μm brightness temperatures for these cool transiting planets is independent of planet temperature, and instead exhibits a tentative correlation with planet mass. If this trend can be confirmed, it would suggest that the shape of these planets' emission spectra depends primarily on their masses, consistent with the hypothesis that lower-mass planets are more likely to have metal-rich atmospheres.",
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AU - Knutson, Heather A.

AU - Line, Michael

AU - Fortney, Jonathan J.

AU - Deming, Drake

AU - Burrows, Adam

AU - Cowan, Nicolas B.

AU - Triaud, Amaury H M J

AU - Agol, Eric

AU - Desert, Jean Michel

AU - Fulton, Benjamin J.

AU - Howard, Andrew W.

AU - Laughlin, Gregory P.

AU - Lewis, Nikole K.

AU - Morley, Caroline V.

AU - Moses, Julianne I.

AU - Showman, Adam P.

AU - Todorov, Kamen O.

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