RAYLEIGH SCATTERING IN THE ATMOSPHERE OF THE WARM EXO-NEPTUNE GJ 3470B

ABSTRACT GJ 3470b is a warm Neptune-size planet transiting an M dwarf star. Like the handful of other small exoplanets for which transmission spectroscopy has been obtained, GJ 3470b exhibits a flat spectrum in the near- and mid-infrared. Recently, a tentative detection of Rayleigh scattering in its...

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Bibliographic Details
Published in:The Astrophysical journal 2015-12, Vol.814 (2), p.1-9
Main Authors: Dragomir, Diana, Benneke, Björn, Pearson, Kyle A., Crossfield, Ian J. M., Eastman, Jason, Barman, Travis, Biddle, Lauren I.
Format: Article
Language:English
Subjects:
ABSORPTION
ABSORPTION SPECTRA
ABSORPTION SPECTROSCOPY
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Atmospheres
Atmospherics
CLOUDS
DETECTION
DWARF STARS
Extrasolar planets
HELIUM
HYDROGEN
INFRARED RADIATION
METERS
NEPTUNE PLANET
planetary systems
RAYLEIGH SCATTERING
Slopes
stars: individual (GJ 3470)
techniques: photometric
TELESCOPES
Transits
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Summary:ABSTRACT GJ 3470b is a warm Neptune-size planet transiting an M dwarf star. Like the handful of other small exoplanets for which transmission spectroscopy has been obtained, GJ 3470b exhibits a flat spectrum in the near- and mid-infrared. Recently, a tentative detection of Rayleigh scattering in its atmosphere has been reported. This signal manifests itself as an observed increase of the planetary radius as a function of decreasing wavelength in the visible. We set out to verify this detection and observed several transits of this planet with the LCOGT network and the Kuiper telescope in four different bands (Sloan g, Sloan i, Harris B, and Harris V). Our analysis reveals a strong Rayleigh scattering slope, thus confirming previous results. This makes GJ 3470b the smallest known exoplanet with a detection of Rayleigh scattering. We find that the most plausible scenario is a hydrogen/helium-dominated atmosphere covered by clouds which obscure absorption features in the infrared and hazes which give rise to scattering in the visible. Our results demonstrate the feasibility of exoplanet atmospheric characterization from the ground, even with meter-class telescopes.
ISSN:0004-637X
1538-4357
1538-4357
DOI:10.1088/0004-637X/814/2/102