Time-resolved image polarimetry of TRAPPIST-1 during planetary transits
AffiliationUniv Arizona, Steward Observ
Univ Arizona, Dept Astron
MetadataShow full item record
PublisherOXFORD UNIV PRESS
CitationP A Miles-Páez, M R Zapatero Osorio, E Pallé, S A Metchev, Time-resolved image polarimetry of TRAPPIST-1 during planetary transits, Monthly Notices of the Royal Astronomical Society: Letters, Volume 484, Issue 1, March 2019, Pages L38–L42, https://doi.org/10.1093/mnrasl/slz001
RightsCopyright © 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society
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AbstractWe obtained linear polarization photometry (J-band) and low-resolution spectroscopy (ZJ-bands) of TRAPPIST-1, which is a planetary system formed by an M8-type low-mass star and seven temperate, Earth-sized planets. The photopolarimetric monitoring campaign covered 6.5 h of continuous observations including one full transit of planet TRAPPIST-1d and partial transits of TRAPPIST-1b and e. The spectrophotometric data and the photometric light curve obtained over epochs with no planetary transits indicate that the low-mass star has very low level of linear polarization compatible with a null value. However, the ‘in transit’ observations reveal an enhanced linear polarization signal with peak values of p∗=0.1 per cent with a confidence level of 3σ, particularly for the full transit of TRAPPIST-1d, thus confirming that the atmosphere of the M8-type star is very likely dusty. Additional observations probing different atmospheric states of TRAPPIST-1 are needed to confirm our findings, as the polarimetric signals involved are low. If confirmed, polarization observations of transiting planetary systems with central ultracool dwarfs can become a powerful tool for the characterization of the atmospheres of the host dwarfs and the validation of transiting planet candidates that cannot be corroborated by any other method.
VersionFinal published version
SponsorsSpanish Ministry of Economics and Competitiveness [ESP2013-48391-C4-2-R, AYA2016-79425-C3-2-P]