GTC OSIRIS transiting exoplanet atmospheric survey: detection of potassium in HAT-P-1b from narrowband spectrophotometry

Abstract

We present the detection of potassium in the atmosphere of HAT-P-1b using optical transit narrowband photometry. The results are obtained using the 10.4 m Gran Telescopio Canarias (GTC) together with the OSIRIS instrument in tunable filter imaging mode. We observed four transits, two at continuum wavelengths outside the potassium feature, at 6792 Å and 8844 Å, and two probing the potassium feature in the line wing at 7582.0 Å and the line core at 7664.9 Å using a 12 Å filter width (R~650). The planet-to-star radius ratios in the continuum are found to be $R_{\mathrm{pl}}/R_{\star }$ = 0.1176 $\pm$ 0.0013 at 6792 Å and $R_{\mathrm{pl}}/R_{\star }$ = 0.1168 $\pm$ 0.0022 at 8844 Å, significantly lower than the two observations in the potassium line: $R_{\mathrm{pl}}/R_{\star }$ = 0.1248 $\pm$ 0.0014 in the line wing at 7582.0 Å and $R_{\mathrm{pl}}/R_{\star }$ = 0.1268 $\pm$ 0.0012 in the line core at 7664.9 Å. With a weighted mean of the observations outside the potassium feature $R_{\mathrm{pl}}/R_{\star }$ = 0.1174 $\pm$ 0.0010, the potassium is detected as an increase in the radius ratio of Δ$R_{\mathrm{pl}}/R_{\star }$ = 0.0073 $\pm$ 0.0017 at 7582.0 Å and Δ$R_{\mathrm{pl}}/R_{\star }$ = 0.0094 $\pm$ 0.0016 at 7664.9 Å (a significance of 4.3 and 6.1 $\sigma$ respectively). We hypothesise that the strong detection of potassium is caused by a large scale height, which can be explained by a high-temperature at the base of the upper atmosphere. A lower mean molecular mass caused by the dissociation of molecular hydrogen into atomic hydrogen by the EUV flux from the host star may also partly explain the amplitude of our detection.

11 pages, 7 figures

References in corpus (11)

• Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates
• The effect of red noise on planetary transit detection
• Sodium Absorption From the Exoplanetary Atmosphere of HD189733b Detected in the Optical Transmission Spectrum
• Rayleigh scattering in the transit spectrum of HD 189733b
• Water Vapour Absorption in the Clear Atmosphere of an exo-Neptune
• Ground-based detection of sodium in the transmission spectrum of exoplanet HD209458b
• HAT-P-1b: A Large-Radius, Low-Density Exoplanet Transiting one Member of a Stellar Binary
• HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering
• HST/STIS Optical Transit Transmission Spectra of the hot-Jupiter HD209458b
• Rayleigh scattering by H2 in the extrasolar planet HD209458b
• Measurement of the Spin-Orbit Angle of Exoplanet HAT-P-1b

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