High contrast polarimetry in the infrared with SPHERE on the VLT

M. Langlois (1) , K. Dohlen (1) , Arthur Vigan (1) , A. Zurlo (1) , C. Moutou (1) , H. M. Schmid (2) , J. Mili (3) , Jean-Luc Beuzit (4) , A. Boccaletti (5) , Michael Carle (1) , Anne Costille (1) , R. Dorn (6) , L. Gluck (7) , N. Hubin (6) , M. Feldt (8) , M. Kasper (6) , L. Lizon (6) , F. Madec (1) , David Le Mignant (1) , David Mouillet (7) , J.-P. Puget (7) , Jean-François Sauvage (9) , F. Wildi (10)

1 LAM - Laboratoire d'Astrophysique de Marseille
2 Institute of Astronomy [ETH Zürich]
3 ESO - European Southern Observatory [Santiago]
4 ONERA - The French Aerospace Lab [Châtillon]
5 LESIA (UMR_8109) - Laboratoire d'études spatiales et d'instrumentation en astrophysique
6 ESO - European Southern Observatory
7 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
8 MPIA - Max-Planck-Institut für Astronomie
9 DOTA, ONERA, Université Paris Saclay (COmUE) [Châtillon]
10 ObsGE - Observatoire Astronomique de l'Université de Genève

The instrument SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch), recently installed on the VLT-UT3, aims to detected and characterize giant extra-solar planets and the circumstellar environments in the very close vicinity of bright stars. The extreme brightness contrast and small angular separation between the planets or disks and their parent stars have so far proven very challenging. SPHERE will meet this challenge by using an extreme AO, stellar coronagraphs, an infrared dual band and polarimetric imager called IRDIS, an integral field spectrograph, and a visible polarimetric differential imager called ZIMPOL. Polarimetry allows a separation of the light coming from an unpolarized source such as a star and the polarized source such as a planet or protoplanetary disks. In this paper we present the performance of the infrared polarimetric imager based on experimental validations performed within SPHERE before the preliminary acceptance in Europe. We report on the level of instrumental polarization in the infrared and its calibration limit. Using differential polarimetry technique, we quantify the level of speckle suppression, and hence improved sensitivity in the context of imaging extended stellar environments.

Domaines: Astrophysique [astro-ph]

M. Langlois, K. Dohlen, Arthur Vigan, A. Zurlo, C. Moutou, et al.. High contrast polarimetry in the infrared with SPHERE on the VLT. SPIE Astronomical Telescopes + Instrumentation, Jul 2014, Montréal, Canada. pp.91471R, ⟨10.1117/12.2055549⟩. ⟨hal-02118417⟩