The Blue Sky of GJ3470b

GJ3470b is a rare example of a "hot Uranus" transiting exoplanet orbiting a nearby M1.5 dwarf. It is of crucial interest for atmospheric studies because it is one of the most inflated low-mass planets known, bridging the boundary between "super-Earths" and Neptunian planets.

We present two new ground-based light curves of GJ3470b gathered by the LBC camera at the Large Binocular Telescope. Simultaneous photometry in the ultraviolet (lambda_c = 357.5 nm) and optical infrared (lambda_c = 963.5 nm) allowed us to detect a significant change of the effective radius of GJ3470b as a function of wavelength. This can be interpreted as a signature of scattering processes occurring in the planetary atmosphere, which should be cloud-free and with a low mean molecular weight.

The unprecedented accuracy of our measurements demonstrates that the photometric detection of Earth-sized planets around M dwarfs is achievable using 8-10m size ground-based telescopes. We provide updated planetary parameters, and a greatly improved orbital ephemeris for any forthcoming study of this planet.

The Blue Sky of GJ3470b: Atmosphere of a Low-mass Planet Unveiled by Ground-based Photometry

V. Nascimbeni, G. Piotto, I. Pagano, G. Scandariato, E. Sani, M. Fumana (Submitted on 30 Aug 2013)

Comments: 8 pages, 6 figures, 1 table; accepted for publication in A&A

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)

Cite as: arXiv:1308.6765 [astro-ph.EP]

(or arXiv:1308.6765v1 [astro-ph.EP] for this version) Submission history From: Valerio Nascimbeni [view email] [v1] Fri, 30 Aug 2013 15:06:06 GMT (131kb)

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