Warm Spitzer observations of three hot exoplanets: XO-4b, HAT-P-6b, and HAT-P-8b

Kamen O. Todorov, Drake Deming, Heather A. Knutson, Adam Burrows, Pedro V. Sada, Nicolas B. Cowan, Eric Agol, Jean Michel Desert, Jonathan J. Fortney, David Charbonneau, Gregory Laughlin, Jonathan Langton, Adam Showman, Nikole K. Lewis

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

We analyze Warm Spitzer/Infrared Array Camera observations of the secondary eclipses of three planets, XO-4b, HAT-P-6b, and HAT-P-8b. We measure secondary eclipse amplitudes at 3.6 μm and 4.5 μm for each target. XO-4b exhibits a stronger eclipse depth at 4.5 μm than at 3.6 μm, which is consistent with the presence of a temperature inversion. HAT-P-8b shows a stronger eclipse amplitude at 3.6 μm and is best described by models without a temperature inversion. The eclipse depths of HAT-P-6b can be fitted with models with a small or no temperature inversion. We consider our results in the context of a postulated relationship between stellar activity and temperature inversion and a relationship between irradiation level and planet dayside temperature, as discussed by Knutson et al. and Cowan & Agol, respectively. Our results are consistent with these hypotheses, but do not significantly strengthen them. To measure accurate secondary eclipse central phases, we require accurate ephemerides. We obtain primary transit observations and supplement them with publicly available observations to update the orbital ephemerides of the three planets. Based on the secondary eclipse timing, we set upper boundaries for ecos (ω) for HAT-P-6b, HAT-P-8b, and XO-4b and find that the values are consistent with circular orbits.

Original languageEnglish (US)
Article number111
JournalAstrophysical Journal
Volume746
Issue number1
DOIs
StatePublished - Feb 10 2012

Fingerprint

temperature inversion
eclipses
extrasolar planets
temperature inversions
planet
ephemerides
planets
irradiation
stellar activity
circular orbits
supplements
transit
cameras
time measurement
inversions
temperature
orbitals

Keywords

  • eclipses
  • planetary systems
  • techniques: photometric

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Todorov, K. O., Deming, D., Knutson, H. A., Burrows, A., Sada, P. V., Cowan, N. B., ... Lewis, N. K. (2012). Warm Spitzer observations of three hot exoplanets: XO-4b, HAT-P-6b, and HAT-P-8b. Astrophysical Journal, 746(1), [111]. https://doi.org/10.1088/0004-637X/746/1/111

Warm Spitzer observations of three hot exoplanets : XO-4b, HAT-P-6b, and HAT-P-8b. / Todorov, Kamen O.; Deming, Drake; Knutson, Heather A.; Burrows, Adam; Sada, Pedro V.; Cowan, Nicolas B.; Agol, Eric; Desert, Jean Michel; Fortney, Jonathan J.; Charbonneau, David; Laughlin, Gregory; Langton, Jonathan; Showman, Adam; Lewis, Nikole K.

In: Astrophysical Journal, Vol. 746, No. 1, 111, 10.02.2012.

Research output: Contribution to journalArticle

Todorov, KO, Deming, D, Knutson, HA, Burrows, A, Sada, PV, Cowan, NB, Agol, E, Desert, JM, Fortney, JJ, Charbonneau, D, Laughlin, G, Langton, J, Showman, A & Lewis, NK 2012, 'Warm Spitzer observations of three hot exoplanets: XO-4b, HAT-P-6b, and HAT-P-8b', Astrophysical Journal, vol. 746, no. 1, 111. https://doi.org/10.1088/0004-637X/746/1/111
Todorov KO, Deming D, Knutson HA, Burrows A, Sada PV, Cowan NB et al. Warm Spitzer observations of three hot exoplanets: XO-4b, HAT-P-6b, and HAT-P-8b. Astrophysical Journal. 2012 Feb 10;746(1). 111. https://doi.org/10.1088/0004-637X/746/1/111
Todorov, Kamen O. ; Deming, Drake ; Knutson, Heather A. ; Burrows, Adam ; Sada, Pedro V. ; Cowan, Nicolas B. ; Agol, Eric ; Desert, Jean Michel ; Fortney, Jonathan J. ; Charbonneau, David ; Laughlin, Gregory ; Langton, Jonathan ; Showman, Adam ; Lewis, Nikole K. / Warm Spitzer observations of three hot exoplanets : XO-4b, HAT-P-6b, and HAT-P-8b. In: Astrophysical Journal. 2012 ; Vol. 746, No. 1.
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