Broad-band spectrophotometry of HAT-P-32 b: search for a scattering signature in the planetary spectrum

• DOI: 10.1093/mnras/stw1999
• Publication Date: 2016-08-12T00:38:17Z
• Authors: M. Mallonn; I. Bernt; E. Herrero; S. Hoyer; J. Kirk; P. J. Wheatley; M. Seeliger; F. Mackebrandt; C. von Essen; K. G. Strassmeier; T. Granzer; A. Künstler; V. S. Dhillon; T. R. Marsh; J. Gaitan
• Keywords: MODEL ATMOSPHERES; BLUE SKY; planets and satellites: individual: HAT-P-32 b; FOS: Physical sciences; atmosphere [planets and satellites]; individual: HAT-P-32 b [planets and satellites]; 01 natural sciences; photometric [techniques]; techniques: photometric; ECLIPSING BINARIES; 0103 physical sciences; planets and satellites: atmosphere; QC; QB; Earth and Planetary Astrophysics (astro-ph.EP); OPTICAL-TRANSMISSION SPECTRUM; EXOPLANET GJ 1214B; TRANSITING EXTRASOLAR PLANETS; OR-EQUAL-TO; 13. Climate action; NEAR-IR; HD 189733B; RAYLEIGH-SCATTERING; Astrophysics - Earth and Planetary Astrophysics

Multi-colour broad-band transit observations offer the opportunity to characterise the atmosphere of an extrasolar planet with small- to medium-sized telescopes. One of the most favourable targets is the hot Jupiter HAT-P-32 b. We combined 21 new transit observations of this planet with 36 previously published light curves for a homogeneous analysis of the broad-band transmission spectrum from the Sloan u' band to the Sloan z' band. Our results rule out cloud-free planetary atmosphere models of solar metallicity. Furthermore, a discrepancy at reddest wavelengths to previously published results makes a recent tentative detection of a scattering feature less likely. Instead, the available spectral measurements of HAT-P-32 b favour a completely flat spectrum from the near-UV to the near-IR. A plausible interpretation is a thick cloud cover at high altitudes.<br/>12 pages, 6 figures, accepted for publication in MNRAS<br/>