The VAMPIRES instrument: imaging the innermost regions of protoplanetary discs with polarimetric interferometry

Abstract

Direct imaging of protoplanetary disks promises to provide key insight into the complex sequence of processes by which planets are formed. However imaging the innermost region of such disks (a zone critical to planet formation) is challenging for traditional observational techniques (such as near-IR imaging and coronagraphy) due to the relatively long wavelengths involved and the area occulted by the coronagraphic mask. Here we introduce a new instrument -VAMPIRES -which combines nonredundant aperture-masking interferometry with differential polarimetry to directly image this previously inaccessible innermost region. By using the polarisation of light scattered by dust in the disk to provide precise differential calibration of interferometric visibilities and closure phases, VAMPIRES allows direct imaging at and beyond the telescope diffraction limit. Integrated into the SCExAO system at the Subaru telescope, VAMPIRES operates at visible wavelengths (where polarisation is high) while allowing simultaneous infrared observations conducted by HICIAO. Here we describe the instrumental design and unique observing technique and present the results of the first on-sky commissioning observations, validating the excellent visibility and closure phase precision which are then used to project expected science performance metrics.

An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme Adaptive Optics System

“…Additionally, interferometric non-redundant spare aperture masking (SAM) modules such as VAMPIRES and FIRST (Huby et al 2012;Norris et al 2015) operating in the visible can reach down to 0.5λ/D (10 mas at 700 nm), albeit at more moderate contrast (∼10 −3 ). Key design choices have been made, which prioritize imaging at small angular separation from day one, for example by using a Pyramid Wavefront Sensor (PyWFS) to improve AO correction close to the star, and by implementing a coronagraphic Lyot-plane low-order wavefront sensor (LLOWFS) (Singh et al 2015).…”

Precision single mode fibre integral field spectroscopy with the RHEA spectrograph

“…Vampires 19 or the SCExAO science camera, it is essential that RHEA is able to run completely in parallel without affecting the other (possibly primary) science program. This must include a complete suite of internal calibration sources.…”

The SCExAO high contrast imager: transitioning from commissioning to science

“…VAMPIRES is an aperture masking inteferometer providing sub-diffraction limited spatial resolution images with polarimetry, and is commissioned and fully operational. 12,17 FIRST is a pupil-remapping interferometer which provides spectral information in addition to high angular resolution images.…”