Self-Phase-Referenced Spectro-Interferometry on the Keck Interferometer

Creators: Woillez, J.; Akeson, R.; Colavita, M.; Eisner, J.; Millan-Gabet, R.; Monnier, J.; Pott, J.-U.; Ragland, S.; Wizinowich, P.; Abajian, M.; Appleby, E.; Berkey, B.; Cooper, A. P.; Felizardo, C.; Herstein, J.; Hrynevych, M.; Medeiros, D.; Morrison, D.; Panteleeva, T.; Smith, B.; Summers, K.; Tsubota, K.; Tyau, C.; Wetherell, E.

Abstract

As part of the astrometric and phase-referenced astronomy (ASTRA) project, three new science modes are being developed for the Keck Interferometer that extend the science capabilities of this instrument to include higher spectral resolution, fainter magnitudes, and astrometry. We report on the successful implementation of the first of these science modes, the self-phase-referencing mode, which provides a K-band (λ = 2.2 μm) spectral resolution of R ∼ 1000 on targets as faint as 7.8 mag with spatial resolution as fine as λ/B = 5 mas in the K band, with the 85 m interferometer baseline. This level of spectral resolution would not have been possible without a phase-referencing implementation extending the integration time limit imposed by atmospheric turbulence. For narrow spectral features, we demonstrate a precision of ± 0.01 on the differential V^2(λ), and ± 1.7 mrad on the differential phase Φ(λ), equivalent to a differential astrometry precision of ± 1.45 μas. This new Keck Interferometer instrument is typically used to study the geometry and location of narrow spectral features at high angular resolution, referenced to a continuum. By simultaneously providing spectral and spatial information, the geometry of velocity fields (e.g., rotating disks, inflows, outflows, etc.) larger than 150 km s^(-1) can also be explored.

Additional Information

© 2012 The Astronomical Society of the Pacific. Received 2011 July 1; accepted 2011 December 7; published 2012 January 30. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community.We are most fortunate to have the opportunity to conduct observations from this mountain. The Keck Interferometer is funded by the National Aeronautics and Space Administration. The ASTRA project was funded by the Major Research Instrumentation program of the National Science Foundation (grant AST-0619965). This work has made use of services produced by the NASA Exoplanet Science Institute at the California Institute of Technology.

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