2008/05/16 by Pavel Machálek, Pavel Machalek, P. R. McCullough +5
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/590140
published as 2008ApJ...684.1427M · 7 pages, 4 figures, 2 tables, accepted for publication to ApJ
arxiv created 2008/05/16 · openalex publication_date 2008/09/04 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We estimate flux ratios of the extrasolar planet XO-1b to its host star XO-1 at 3.6, 4.5, 5.8, and 8.0 μm with IRAC on the Spitzer Space Telescope to be 0.00086 ± 0.00007, 0.00122 ± 0.00009, 0.00261 ± 0.00031, and 0.00210 ± 0.00029, respectively. The fluxes are inconsistent with a canonical cloudless model for the thermal emission from a planet and suggest an atmosphere with a thermal inversion layer and a possible stratospheric absorber. A newly emerging correlation between the presence of a thermal inversion layer in the planetary atmosphere and stellar insolation of the planet, as by Burrows and colleagues, is refined. The substellar point flux from the parent star at XO-1b of ~0.49 × 10 9 erg cm −2 s −1 sets a new lower limit for the occurrence of a thermal inversion in a planetary atmosphere.