Heather A. Knutson

Learn More
'Hot Jupiter' extrasolar planets are expected to be tidally locked because they are close (<0.05 astronomical units, where 1 au is the average Sun-Earth distance) to their parent stars, resulting in permanent daysides and nightsides. By observing systems where the planet and star periodically eclipse each other, several groups have been able to estimate the(More)
We estimate the strength of the bandpass-integrated thermal emission from the extrasolar planet HD 209458b at 3.6, 4.5, 5.8, and 8.0 µm using the In-frared Array Camera (IRAC) on the Spitzer Space Telescope. We observe a single secondary eclipse simultaneously in all four bandpasses and find relative eclipse depths of 0.00094 ± 0.00009, 0.00213 ± 0.00015,(More)
We report on the BVRI multi-band follow-up photometry of the transiting extrasolar planet HD 189733b. We revise the transit parameters and find planetary radius R P = 1.154 ± 0.032R J and inclination i P = 85.79 ± 0.24 •. The new density (∼ 1g cm −3) is significantly higher than the former estimate (∼ 0.75g cm −3); this shows that from the current sample of(More)
GJ 436b is a warm--approximately 800 kelvin--exoplanet that periodically eclipses its low-mass (half the mass of the Sun) host star, and is one of the few Neptune-mass planets that is amenable to detailed characterization. Previous observations have indicated that its atmosphere has a ratio of methane to carbon monoxide that is 10(5) times smaller than(More)
In this paper, we describe a uniform analysis of eight transits and eleven secondary eclipses of the extrasolar planet GJ 436b obtained in the 3.6, 4.5, and 8.0 μm bands using the IRAC instrument on the Spitzer Space Telescope between UT 2007 June 29 and UT 2009 February 4. We find that the best-fit transit depths for visits in the same bandpass can vary by(More)
We present an optical to near-infrared transmission spectrum of the hot Jupiter HAT-P-1b, based on Hubble Space Telescope observations, covering the spectral regime from 0.29 to 1.027 μm with Space Telescope Imaging Spectrograph (STIS), which is coupled with a recent Wide Field Camera 3 (WFC3) transit (1.087 to 1.687 μm). We derive refined physical(More)
We use multi-band photometry to refine estimates for the planetary radius and orbital inclination of the transiting planet system HD 209458. We gathered 1066 spectra over four distinct transits with the STIS spectrometer on the Hubble Space Telescope using two gratings with a resolution R = 1500 and a combined wavelength range of 290 − 1030 nm. We divide(More)
The nearby transiting planet HD 189733b was observed during three transits with the ACS camera of the Hubble Space Telescope in spectroscopic mode. The resulting time series of 675 spectra covers the 550-1050 nm range, with a resolution element of ∼ 8 nm, at extremely high accuracy (signal-to-noise ratio up to 10,000 in 50 nm intervals in each individual(More)
We present Spitzer Space Telescope time series photometry of the exoplanet system HD 189733 spanning two times of secondary eclipse, when the planet passes out of view behind the parent star. We estimate the relative eclipse depth in 5 distinct bands and find the planet-to-star flux ratio to be 0. For consistency, we re-analyze a previously published time(More)
The nearby transiting system GJ 436b offers a unique opportunity to probe the structure and atmosphere of an extra-solar " hot Neptune ". In this Letter, we present the main results of observations covering two transit events with the NICMOS camera on the Hubble Space Telescope. The data consist in high-cadence time series of grism spectra covering the(More)