期刊
ASTRONOMY & ASTROPHYSICS
卷 505, 期 2, 页码 891-899出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/200912776
关键词
planetary systems; stars: individual: HD 189733; techniques: photometric; binaries: eclipsing
资金
- NASA [GO-11117]
- NSF
- Tennessee State University
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 mu m and two performed with a narrowband filter at 1.66 mu 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 H2O below 2 mu m at a 5 sigma confidence level. We measure a planet-to-star radius contrast of 0.15498 +/- 0.00035 at 1.66 mu m and a contrast of 0.15517 +/- 0.00019 at 1.87 mu 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 mu m.
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