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|Title:||Broad-band spectrophotometry of the hot Jupiter HAT-P-12b from the near-UV to the near-IR||Authors:||Mallonn, M.
von Essen, C.
Strassmeier, K. G.
Sada, P. V.
Dhillon, V. S.
Marsh, T. R.
|Issue Date:||2015||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||583||First Page:||A138||Abstract:||Context. The detection of trends or gradients in the transmission spectrum of extrasolar planets is possible with observations at very low spectral resolution. Transit measurements of sufficient accuracy using selected broad-band filters allow for an initial characterization of the atmosphere of the planet. Aims: We want to investigate the atmosphere of the hot Jupiter HAT-P-12b for an increased absorption at the very blue wavelength regions caused by scattering. Furthermore, we aim for a refinement of the transit parameters and the orbital ephemeris. Methods: We obtained time series photometry of 20 transit events and analyzed them homogeneously, along with eight light curves obtained from the literature. In total, the light curves span a range from 0.35 to 1.25 microns. During two observing seasons over four months each, we monitored the host star to constrain the potential influence of starspots on the derived transit parameters. Results: We rule out the presence of a Rayleigh slope extending over the entire optical wavelength range, a flat spectrum is favored for HAT-P-12b with respect to a cloud-free atmosphere model spectrum. A potential cause of such gray absorption is the presence of a cloud layer at the probed latitudes. Furthermore, in this work we refine the transit parameters, the ephemeris and perform a TTV analysis in which we found no indication for an unseen companion. The host star showed a mild non-periodic variability of up to 1%. However, no stellar rotation period could be detected to high confidence.||Acknowledgments:||Based on observations made with the Large Binocular Telescope (LBT), the Italian Telescopio Nazionale Galileo (TNG), the William Herschel Telescope (WHT), the Nordic Optical Telescope (NOT), the Joan Oró Telescope (TJO) of the Montsec Astronomical Observatory (OAdM), the STELLA telescope, and on observations collected at Asiago observatory. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. The TNG, WHT, and NOT are operated on the island of La Palma at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias (IAC). The TNG is operated by the Fundación Galileo Galilei of the Istituto Nazionale di Astrofisica (INAF). The WHT is operated by the Isaac Newton Group and is run by the Royal Greenwich Observatory at the Spanish Roque de los Muchachos Observatory in La Palma. The NOT is operated jointly by Denmark, Finland, Iceland, Norway, and Sweden. The TJO of OAdM is owned by the Catalan Government and operated by the Institute for Space Studies of Catalonia (IEEC). STELLA is owned by the Leibniz Institute for Astrophysics Potsdam (AIP), which is jointly operated by AIP and IAC. We are grateful for DDT observing time at the TNG and for the acceptance of a Fast-Track program at the NOT. We wish to acknowledge all technical support at these observing facilities. We thank Jonathan Fortney for providing the cloud-free solar-composition atmospheric model for HAT-P-12b and the anonymous referee for many thoughtful comments, which significantly improved the manuscript.||URI:||http://hdl.handle.net/20.500.12386/23513||URL:||https://www.aanda.org/articles/aa/abs/2015/11/aa25395-14/aa25395-14.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201425395||Bibcode ADS:||2015A&A...583A.138M||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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