High-contrast imaging of tight resolved binaries with two vector vortex coronagraphs in cascade with the Palomar SDC instrument

Abstract

More than half of the stars in the solar neighborhood reside in binary/multiple stellar systems, and recent studies suggest that gas giant planets may be more abundant around binaries than single stars. Yet, these multiple systems are usually overlooked or discarded in most direct imaging surveys, as they prove difficult to image at high-contrast using coronographs. This is particularly the case for compact binaries (less than 1'' angular separation) with similar stellar magnitudes, where no existing coronagraph can provide high-contrast regime. Here we present preliminary results of an on-going Palomar pilot survey searching for low-mass companions around ~15 young "challenging" binary systems, with angular separation as close as 0''3 and near-equal K-band magnitudes. We use the Stellar Double Coronagraph (SDC) instrument on the 200-inch Telescope in a modified optical configuration, making it possible to align any targeted binary system behind two vector vortex coronagraphs in cascade. This approach is uniquely possible at Palomar, thanks to the absence of sky rotation combined with the availability of an extreme AO system, and the number of intermediate focalplanes provided by the SDC instrument. Finally, we expose our current data reduction strategy, and we attempt to quantify the exact contrast gain parameter space of our approach, based on our latest observing runs.

SLM-based active focal-plane coronagraphy: status and future on-sky prospects

“…To name a few, one could make strong use of the available observing time to setup systematic follow-up programs of large transit missions, such as TESS and PLATO, or rely on the niche PLACID features to be able to survey a large population of binary or multiple-star systems in high-contrast imaging mode, in the wake of recent efforts undertaken with the Stellar Double Coronagraph (SDC) instrument on the Palomar Hale Telescope. 16…”

Habitable Exoplanet Observatory (HabEx) telescope and optical instruments

“…Higher topological charges produce less sensitivity to low order optical aberrations resulting in larger IWAs (inner working angles), so the choice of charge is an important factor. State of the art vortex coronagraph masks [5] have been built using one of the following technologies: liquid crystal polymers (LCP), photonics crystals (PC), or subwavelength gratings. The best lab results for vortex masks have been obtained on the High Contrast Imaging Testbed (HCIT) with the LCP approach.…”

Design and performance of the PALM-3000 3.5 kHz upgrade

“…This high-order correction was necessary for the driving science cases of the system, including imaging of faint Kuiper Belt Objects, stellar evolution studies of pre-main sequence binaries at visible wavelengths, and, especially, the direct imaging and spectroscopy of circumstellar environments and hot, young exo-Jupiters with the P1640 high-contrast integral field spectrograph (IFS) [4]. In addition to the main P1640 survey and the continued utilization of the facility Palomar High Angular Resolution Observer [5,PHARO], P3K has served as a vital testbed for other high-resolution and high-contrast instruments and technology demonstrations, including the ten-milliarcseconds per-pixel EM-CCD camera (TMAS) and a myriad of experiments [6,7,8,9] with the Stellar Double Coronagraph [10].…”