Possible detection of a bimodal cloud distribution in the atmosphere of HAT-P-32Ab from multiband photometry

• We present high-precision photometry of eight separate transit events in the HAT-P-32 planetary system. One transit event was observed simultaneously by two telescopes of which one obtained a simultaneous multiband light curve in three optical bands, giving a total of 11 transit light curves. Due to the filter selection and in conjunction with using the defocused photometry technique, we were able to obtain an extremely high-precision, ground-based transit in the u band (350 nm), with an rms scatter of approximate to 1 mmag. All 11 transits were modelled using PRISM and GEMC, and the physical properties of the system calculated. We find the mass and radius of the host star to be 1.182 +/- 0.041 M-circle dot and 1.225 +/- 0.015 R-circle dot, respectively. For the planet, we find a mass of 0.80 +/- 0.14 M-Jup, a radius of 1.807 +/- 0.022 R-Jup, and a density of 0.126 +/- 0.023 rho(Jup). These values are consistent with those found in the literature. We also obtain a new orbital ephemeris for the system T-0 = BJD/TDB 2 454 420.447187(96)+2.15000800(10) x E. We measured the transmission spectrum of HAT-P-32Ab and compared it to theoretical transmission spectra. Our results indicate a bimodal cloud particle distribution consisting of Rayleigh-like haze and grey absorbing cloud particles within the atmosphere of HAT-P-32Ab.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

techniques: photometric

planets and satellites: atmospheres

planets and satellites: gaseous planets

stars: fundamental parameters

stars: individual: HAT-P-32

Aplanetary systems

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