Time-resolved image polarimetry of TRAPPIST-1 during planetary transits

Miles-Páez, Paulo A.; Osorio, M. R. Zapatero; Pallé, E.; Metchev, Stanimir

doi:10.1093/mnrasl/slz001

Cited by 9 publications

(7 citation statements)

References 31 publications

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“…In addition, current contamination models only account for spots or faculaes or their combinations, but the atmosphere of TRAPPIST-1 could contain dust. Miles-Páez et al (2019) using linear polarization photometry in the near-IR J band finds hints that the atmosphere of TRAPPIST-1 is quite dusty. Likely, this should also be included for proper accounting of stellar contamination.…”

Section: Updated Transmission Spectra and Stellar Contaminationmentioning

confidence: 99%

Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared

Burdanov

Lederer

Gillon

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The TRAPPIST-1 planetary system is a favorable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb Space Telescope (JWST). A possible obstacle to this technique could come from the photospheric heterogeneity of the host star that could affect planetary signatures in the transit transmission spectra. To constrain further this possibility, we gathered an extensive photometric data set of 25 TRAPPIST-1 transits observed in the near-IR J band (1.2 µm) with the UKIRT and the AAT, and in the NB2090 band (2.1 µm) with the VLT during the period 2015-2018. In our analysis of these data, we used a special strategy aiming to ensure uniformity in our measurements and robustness in our conclusions. We reach a photometric precision of ∼ 0.003 (RMS of the residuals), and we detect no significant temporal variations of transit depths of TRAPPIST-1 b, c, e, and g over the period of three years. The few transit depths measured for planets d and f hint towards some level of variability, but more measurements will be required for confirmation. Our depth measurements for planets b and c disagree with the stellar contamination spectra originating from the possible existence of bright spots of temperature 4500 K. We report updated transmission spectra for the six inner planets of the system which are globally flat for planets b and g and some structures are seen for planets c, d, e, and f.

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Section: Updated Transmission Spectra and Stellar Contaminationmentioning

confidence: 99%

Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared

Burdanov

Lederer

Gillon

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Transits from seven small rocky planets on short period orbits were found, allowing detailed studies to be conducted on the possible atmospheres and their constituents of small planets orbiting a single star, and hence with similar initial conditions (e.g. Alberti et al 2017;Ducrot et al 2018;Moran et al 2018;Miles-Páez et al 2019;Burdanov et al 2019).…”

Section: Introductionmentioning

confidence: 99%

GJ 357: a low-mass planetary system uncovered by precision radial velocities and dynamical simulations

Jenkins

Pozuelos

Tuomi

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We report the detection of a new planetary system orbiting the nearby M2.5V star GJ 357, using precision radial-velocities from three separate echelle spectrographs, HARPS, HiRES, and UVES. Three small planets have been confirmed in the system, with periods of 9.125±0.001, 3.9306±0.0003, and 55.70±0.05 days, and minimum masses of 3.33±0.48, 2.09±0.32, and 6.72±0.94 M ⊕ , respectively. The second planet in our system, GJ 357c, was recently shown to transit by the Transiting Exoplanet Survey Satellite (TESS; Luque et al. 2019), but we could find no transit signatures for the other two planets. Dynamical analysis reveals the system is likely to be close to coplanar, is stable on Myrs timescales, and places strong upper limits on the masses of the two non-transiting planets b and d of 4.25 and 11.20 M ⊕ , respectively. Therefore, we confirm the system contains at least two super-Earths, and either a third super-Earth or mini-Neptune planet. GJ 357b & c are found to be close to a 7:3 mean motion resonance, however no libration of the orbital parameters was found in our simulations. Analysis of the photometric lightcurve of the star from the TESS, when combined with our radial-velocities, reveal GJ 357c has an absolute mass, radius, and density of 2.248 +0.117 −0.120 M ⊕ , 1.167 +0.037 −0.036 R ⊕ , and 7.757 +0.889 −0.789 gcm −3 , respectively. Comparison to super-Earth structure models reveals the planet is likely an iron dominated world. The GJ 357 system adds to the small sample of low-mass planetary systems with well constrained masses, and further observational and dynamical follow-up is warranted to better understand the overall population of small multi-planet systems in the solar neighbourhood.

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“…For example, the thermal emission from a directly imaged giant exoplanet can be polarized in the infrared region (e.g., Jensen-Clem et al 2020;Sanghavi & Shporer 2018;Stolker et al 2017;Sengupta 2013;Marley & Sengupta 2011) due to reasons such as rotation induced oblateness of the planet, nonuniform or banded cloud patterns, gravitational darkening, etc., as is found in the case of the brown dwarfs (e.g., Jensen-Clem et al 2020;Millar-Blanchaer et al 2020;Sanghavi & West 2019;Sengupta 2016;Sengupta & Marley 2010. On the other hand, time-dependent polarization may arise when a planet transits a dusty ultra-cool dwarf (a red dwarf or a brown dwarf), or when an Exomoon transits a cloudy (or hazy) directly imaged exoplanet (e.g., Miles-Páez et al 2019;Sengupta 2018;Sengupta & Marley 2016).…”

Section: Introductionmentioning

confidence: 99%

Generic Models for Disk-Resolved and Disk-Integrated Phase Dependent Linear Polarization of Light Reflected from Exoplanets

Chakrabarty,

Sengupta

2021

Preprint

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Similar to the case of solar system planets, reflected starlight from exoplanets is expected to be polarized due to atmospheric scattering and the net disk integrated polarization should be non-zero owing to the asymmetrical illumination of the planetary disk. The computation of the disk-integrated reflected flux and its state of polarization involves techniques for the calculation of the local reflection matrices as well as the numerical recipes for integration over the planetary disks. In this paper, we present a novel approach to calculate the azimuth-dependent reflected intensity vectors at each location on the planetary disk divided into grids. We achieve this by solving the vector radiative transfer equations that describe linear polarization. Our calculations incorporate self-consistent atmospheric models of exoplanets over a wide range of equilibrium temperature, surface gravity, atmospheric composition, and cloud structure. A comparison of the flux and the amount of polarization calculated by considering both single and multiple scattering exhibits the effect of depolarization due to multiple scattering of light depending on the scattering albedo of the atmosphere. We have benchmarked our basic calculations against some of the existing models. We have also presented our models for the hot Jupiter HD 189733 b, indicating the level of precision required by future observations to detect the polarization of this planet in the optical and near-infrared wavelength region. The generic nature and the accuracy offered by our models make them an effective tool for modeling the future observations of the polarized light reflected from exoplanets.

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Time-resolved image polarimetry of TRAPPIST-1 during planetary transits

Cited by 9 publications

References 31 publications

Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared

Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared

GJ 357: a low-mass planetary system uncovered by precision radial velocities and dynamical simulations

Generic Models for Disk-Resolved and Disk-Integrated Phase Dependent Linear Polarization of Light Reflected from Exoplanets

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