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A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS. First polarimetric detections revealing disks around DH Tau B and GSC 6214-210 B

van Holstein, R. G. and Stolker, T. and Jensen-Clem, R. and Ginski, C. and Milli, J. and De Boer, J. and Girard, J. H. and Wahhaj, Z. and Bohn, A. J. and Millar-Blanchaer, M. A. and Benisty, M. and Bonnefoy, M. and Chauvin, G. and Dominik, C. and Hinkley, S. and Keller, C. U. and Keppler, M. and Langlois, M. and Marino, S. and Ménard, F. and Perrot, C. and Schmidt, T. O. B. and Vigan, A. and Zurlo, A. and Snik, F. (2021) A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS. First polarimetric detections revealing disks around DH Tau B and GSC 6214-210 B. Astronomy and Astrophysics, 647 . Art. No. A21. ISSN 0004-6361.

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Context. Young giant planets and brown dwarf companions emit near-infrared radiation that can be linearly polarized up to several percent. This polarization can reveal the presence of an (unresolved) circumsubstellar accretion disk, rotation-induced oblateness of the atmosphere, or an inhomogeneous distribution of atmospheric dust clouds. Aims. We aim to measure the near-infrared linear polarization of 20 known directly imaged exoplanets and brown dwarf companions. Methods. We observed the companions with the high-contrast imaging polarimeter SPHERE-IRDIS at the Very Large Telescope. We reduced the data using the IRDAP pipeline to correct for the instrumental polarization and crosstalk of the optical system with an absolute polarimetric accuracy <0.1% in the degree of polarization. We employed aperture photometry, angular differential imaging, and point-spread-function fitting to retrieve the polarization of the companions. Results. We report the first detection of polarization originating from substellar companions, with a polarization of several tenths of a percent for DH Tau B and GSC 6214-210 B in H-band. By comparing the measured polarization with that of nearby stars, we find that the polarization is unlikely to be caused by interstellar dust. Because the companions have previously measured hydrogen emission lines and red colors, the polarization most likely originates from circumsubstellar disks. Through radiative transfer modeling, we constrain the position angles of the disks and find that the disks must have high inclinations. For the 18 other companions, we do not detect significant polarization and place subpercent upper limits on their degree of polarization. We also present images of the circumstellar disks of DH Tau, GQ Lup, PDS 70, β Pic, and HD 106906. We detect a highly asymmetric disk around GQ Lup and find evidence for multiple scattering in the disk of PDS 70. Both disks show spiral-like features that are potentially induced by GQ Lup B and PDS 70 b, respectively. Conclusions. The presence of the disks around DH Tau B and GSC 6214-210 B as well as the misalignment of the disk of DH Tau B with the disk around its primary star suggest in situ formation of the companions. The non-detections of polarization for the other companions may indicate the absence of circumsubstellar disks, a slow rotation rate of young companions, the upper atmospheres containing primarily submicron-sized dust grains, and/or limited cloud inhomogeneity.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
van Holstein, R. G.0000-0003-1520-8405
Stolker, T.0000-0002-5823-3072
Jensen-Clem, R.0000-0003-0054-2953
Ginski, C.0000-0002-4438-1971
Milli, J.0000-0001-9325-2511
De Boer, J.0000-0002-1028-7522
Girard, J. H.0000-0001-8627-0404
Wahhaj, Z.0000-0001-8269-324X
Bohn, A. J.0000-0003-1401-9952
Millar-Blanchaer, M. A.0000-0001-6205-9233
Benisty, M.0000-0002-7695-7605
Bonnefoy, M.0000-0001-5579-5339
Dominik, C.0000-0002-3393-2459
Hinkley, S.0000-0001-8074-2562
Keller, C. U.0000-0002-1368-841X
Keppler, M.0000-0001-7250-074X
Ménard, F.0000-0002-1637-7393
Vigan, A.0000-0002-5902-7828
Zurlo, A.0000-0002-5903-8316
Snik, F.0000-0003-1946-7009
Additional Information:© ESO 2021. Article published by EDP Sciences. Received 30 August 2020; Accepted 18 December 2020; Published online 02 March 2021. Based on observations collected at the European Southern Observatory under ESO programs 098.C-0790, 0101.C-0502, 0101.C-0635, 0101.C-0855, 0102.C-0453, 0102.C-0466, 0102.C-0871, 0102.C-0916, and 0104.C-0265 R.Gv.H. thanks ESO for the studentship at ESO Santiago during which part of this project was performed. T.S. acknowledges the support from the ETH Zurich Postdoctoral Fellowship Program. The research of F.S., J.dB., and A.J.B. leading to these results has received funding from the European Research Council under ERC Starting Grant agreement 678194 (FALCONER). C.P. acknowledges financial support from Fondecyt (grant 3190691) and from the ICM (Iniciativa Científica Milenio) via the Núcleo Milenio de Formación Planetaria grant, from the Universidad de Valparaíso. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France; NASA’s Astrophysics Data System Bibliographic Services; Scipy, a free and open-source Python library used for scientific computing and technical computing (Virtanen et al. 2020); and Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018).
Funding AgencyGrant Number
European Southern Observatory (ESO)UNSPECIFIED
European Research Council (ERC)678194
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)319069
Iniciativa Científica MilenioUNSPECIFIED
Universidad de ValparaísoUNSPECIFIED
Subject Keywords:methods: observational – techniques: high angular resolution – techniques: polarimetric – planets and satellites: formation – planets and satellites: atmospheres – protoplanetary disks
Record Number:CaltechAUTHORS:20210303-075100697
Persistent URL:
Official Citation:A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS - First polarimetric detections revealing disks around DH Tau B and GSC 6214-210 B. R.G. van Holstein, T. Stolker, R. Jensen-Clem, C. Ginski, J. Milli, J. de Boer, J.H. Girard, Z. Wahhaj, A.J. Bohn, M.A. Millar-Blanchaer, M. Benisty, M. Bonnefoy, G. Chauvin, C. Dominik, S. Hinkley, C.U. Keller, M. Keppler, M. Langlois, S. Marino, F. Ménard, C. Perrot, T.O.B. Schmidt, A. Vigan, A. Zurlo and F. Snik. A&A, 647 (2021) A21; DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108285
Deposited By: Tony Diaz
Deposited On:03 Mar 2021 17:30
Last Modified:03 Mar 2021 17:30

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