2009/07/29 by David K. Sing, J. -M. Desert, Jean-Michel Désert +11 · 168 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Exoplanet #Hot Jupiter #Photometry (optics) #Physics #Planet #Stars #Stellar, planetary, and galactic studies #Transit (satellite) #astro-ph.EP
paper · pdf · doi:10.1051/0004-6361/200912776
published in Astronomy and Astrophysics 505(2), 891-899 (EDP Sciences) · 9 pages, 7 figures. Accepted for publication in A&A
arxiv created 2009/07/29 · openalex publication_date 2009/08/03 · arxiv updated 2015/05/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
We present Hubble Space Telescope near-infrared transit photometry of the nearby hot-Jupiter HD 189733b. The observations were taken with the NICMOS instrument during five transits, with three transits executed with a narrowband filter at 1.87 <i>μ<i/>m and two performed with a narrowband filter at 1.66 <i>μ<i/>m. Our observing strategy using narrowband filters is insensitive to the usual HST intra-orbit and orbit-to-orbit measurement of systematic errors, allowing us to accurately and robustly measure the near-IR wavelength dependance of the planetary radius. Our measurements fail to reproduce the previously claimed detection of an absorption signature of atmospheric H<sub>2<sub/>O below 2 <i>μ<i/>m at a 5<i>σ<i/> confidence level. We measure a planet-to-star radius contrast of at 1.66 <i>μ<i/>m and a contrast of at 1.87 <i>μ<i/>m. Both of our near-IR planetary radii values are in excellent agreement with the levels expected from Rayleigh scattering by sub-micron haze particles, observed at optical wavelengths, indicating that upper-atmospheric haze still dominates the near-IR transmission spectra over the absorption from gaseous molecular species at least below 2 <i>μ<i/>m.