Near-UV transit photometry of HAT-P-32 b with the LBT: Silicate aerosols in the planetary atmosphere

Abstract

Broad-band exoplanet transit photometry can characterize the planetary atmosphere when observed at multiple selected filters. This observing technique can reveal gradients in the spectra of extrasolar planets, for example the slope of decreasing opacity from short to long optical wavelengths caused by aerosol scattering. In this work we observed a transit of the hot Jupiter HAT-P-32 b in the shortest wavelength possible from the ground using the Large Binocular Telescope (LBT). The data comprise the best-quality ground-based U-band taken so far of an exoplanet transit. Compared to broad-band observations of intermediate and long optical wavelength published previously, a clear scattering slope in the planetary transmission spectrum is revealed. Most likely, the scattering particles are magnesium silicate aerosols larger than 0.1 micrometer. We define a spectral index to compare this scattering feature of HAT-P-32 b to published results of other exoplanets. It turns out to be very typical in amplitude within the comparison sample. Furthermore, we searched for correlation in this sample of the spectral index with planetary equilibrium temperature, surface acceleration and stellar activity indicator, but could not reveal any.

accepted for publication in Astronomical Notes (AN). Version2, several typos corrected

References in corpus (17)

• Rayleigh scattering in the transit spectrum of HD 189733b
• Homogeneous studies of transiting extrasolar planets. I. Light curve analyses
• The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b
• Transmission spectral properties of clouds for hot Jupiter exoplanets
• Near-UV Absorption, Chromospheric Activity, and Star-Planet Interactions in the WASP-12 system
• A consistent retrieval analysis of 10 Hot Jupiters observed in transmission
• Early UV Ingress in WASP-12b: Measuring Planetary Magnetic Fields
• High temperature condensate clouds in super-hot Jupiter atmospheres
• HST hot-Jupiter transmission spectral survey: Haze in the atmosphere of WASP-6b
• Impact of occultations of stellar active regions on transmission spectra: Can occultation of a plage mimic the signature of a blue sky?
• The performance of the blue prime focus Large Binocular Camera at the Large Binocular Telescope
• High accuracy transit photometry of the planet OGLE-TR-113b with a new deconvolution-based method
• Transmission spectroscopy of the inflated exoplanet WASP-52b, and evidence for a bright region on the stellar surface
• Transit Timing Analysis in the HAT-P-32 system
• Characterization of the atmosphere of the hot Jupiter HAT-P-32Ab and the M-dwarf companion HAT-P-32B
• Near-UV and optical observations of the transiting exoplanet TrES-3b
• Broad-band spectrophotometry of HAT-P-32 b: Search for a scattering signature in the planetary spectrum

Cited by in corpus (10)

• Detection of ionized calcium in the atmosphere of the ultra-hot Jupiter KELT-9b
• H$\alpha$ and He I absorption in HAT-P-32 b observed with CARMENES -- Detection of Roche lobe overflow and mass loss
• Low albedos of hot to ultra-hot Jupiters in the optical to near-infrared transition regime
• The HST PanCET Program: An Optical to Infrared Transmission Spectrum of HAT-P-32Ab
• HST/STIS transmission spectrum of the ultra-hot Jupiter WASP-76 b confirms the presence of sodium in its atmosphere
• Probing the atmosphere of WASP-69 b with low- and high-resolution transmission spectroscopy
• LRG-BEASTS: Ground-based Detection of Sodium and a Steep Optical Slope in the Atmosphere of the Highly Inflated Hot-Saturn WASP-21b
• Role of the impact parameter in exoplanet transmission spectroscopy
• HAT-P-58b -- HAT-P-64b: Seven Planets Transiting Bright Stars
• A Two-limb Explanation for the Optical-to-infrared Transmission Spectrum of the Hot Jupiter HAT-P-32Ab