Vortex Fiber Nulling for Exoplanet Observations: Implementation and First Light

Abstract

Vortex fiber nulling (VFN) is a single-aperture interferometric technique for detecting and characterizing exoplanets separated from their host star by less than a diffracted beam width. VFN uses a vortex mask and single mode fiber to selectively reject starlight while coupling off-axis planet light with a simple optical design that can be readily implemented on existing direct imaging instruments that can feed light to an optical fiber. With its axially symmetric coupling region peaking within the inner working angle of conventional coronagraphs, VFN is more efficient at detecting new companions at small separations than conventional direct imaging, thereby increasing the yield of on-going exoplanet search campaigns. We deployed a VFN mode operating in K band ($2.0-2.5\mu$m) on the Keck Planet Imager and Characterizer (KPIC) instrument at the Keck II Telescope. In this paper we present the instrument design of this first on-sky demonstration of VFN and the results from on-sky commissioning, including planet and star throughput measurements and predicted flux-ratio detection limits for close-in companions. The instrument performance is shown to be sufficient for detecting a companion $10^3$ times fainter than a $5^{\mathrm{th}}$ magnitude host star in 1 hour at a separation of 50 mas (1.1$\lambda /D$). This makes the instrument capable of efficiently detecting substellar companions around young stars. We also discuss several routes for improvement that will reduce the required integration time for a detection by a factor $>$3.

26 pages, 5 figures; Accepted to JATIS

References in corpus (23)

• The Gemini Planet Imager: First Light
• The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AU
• The fast spin-rotation of a young extrasolar planet
• Detection of Carbon Monoxide and Water Absorption Lines in an Exoplanet Atmosphere
• The Hipparcos-Gaia Catalog of Accelerations: Gaia EDR3 Edition
• Combining high-dispersion spectroscopy (HDS) with high contrast imaging (HCI): Probing rocky planets around our nearest neighbors
• Atmospheric characterization of Proxima b by coupling the Sphere high-contrast imager to the Espresso spectrograph
• The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report
• The LUVOIR Mission Concept Study Final Report
• Efficient injection from large telescopes into single-mode fibres: Enabling the era of ultra-precision astronomy
• Detection and Bulk Properties of the HR 8799 Planets with High Resolution Spectroscopy
• Direct imaging discovery of a super-Jovian around the young Sun-like star AF Leporis
• A Clear View of a Cloudy Brown Dwarf Companion from High-Resolution Spectroscopy
• A catalogue of stellar diameters and fluxes for mid-infrared interferometry
• Detecting exomoons from radial velocity measurements of self-luminous planets: application to observations of HR 7672 B and future prospects
• First-light LBT nulling interferometric observations: warm exozodiacal dust resolved within a few AU of eta Corvi
• Retrieving the C and O Abundances of HR 7672~AB: a Solar-Type Primary Star with a Benchmark Brown Dwarf
• Comparing Non-Redundant Masking and Filled-Aperture Kernel Phase for Exoplanet Detection and Characterization
• A Rotation Rate for the Planetary-Mass Companion DH Tau b
• Phase II of the Keck Planet Imager and Characterizer: system-level laboratory characterization and preliminary on-sky commissioning
• Detection of a low-mass stellar companion to the accelerating A2IV star HR 1645
• Broadband vortex fiber nulling: high-dispersion exoplanet science at the diffraction limit
• Planet Search with the Keck/NIRC2 Vortex Coronagraph in Ms-band for Vega