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Proceedings Paper

Science with the Keck Interferometer ASTRA program
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Paper Abstract

The ASTrometric and phase-Referenced Astronomy (ASTRA) project will provide phase referencing and astrometric observations at the Keck Interferometer, leading to enhanced sensitivity and the ability to monitor orbits at an accuracy level of 30-100 microarcseconds. Here we discuss recent scientific results from ASTRA, and describe new scientific programs that will begin in 2010-2011. We begin with results from the "self phase referencing" (SPR) mode of ASTRA, which uses continuum light to correct atmospheric phase variations and produce a phase-stabilized channel for spectroscopy. We have observed a number of protoplanetary disks using SPR and a grism providing a spectral dispersion of ~ 2000. In our data we spatially resolve emission from dust as well as gas. Hydrogen line emission is spectrally resolved, allowing differential phase measurements across the emission line that constrain the relative centroids of different velocity components at the 10 microarcsecond level. In the upcoming year, we will begin dual-field phase referencing (DFPR) measurements of the Galactic Center and a number of exoplanet systems. These observations will, in part, serve as precursors to astrometric monitoring of stellar orbits in the Galactic Center and stellar wobbles of exoplanet host stars. We describe the design of several scientific investigations capitalizing on the upcoming phase-referencing and astrometric capabilities of ASTRA.

Paper Details

Date Published: 21 July 2010
PDF: 9 pages
Proc. SPIE 7734, Optical and Infrared Interferometry II, 773411 (21 July 2010); doi: 10.1117/12.856418
Show Author Affiliations
J. A. Eisner, Steward Observatory, The Univ. of Arizona (United States)
R. Akeson, California Institute of Technology (United States)
M. Colavita, Jet Propulsion Lab. (United States)
A. Ghez, Univ. of California, Los Angeles (United States)
J. Graham, Univ. of California, Berkeley (United States)
L. Hillenbrand, California Institute of Technology (United States)
R. Millan-Gabet, California Institute of Technology (United States)
J. D. Monnier, Univ. of Michigan (United States)
J. U. Pott, Max-Planck-Institut für Astronomie (Germany)
S. Ragland, W. M. Keck Observatory (United States)
P. Wizinowich, W. M. Keck Observatory (United States)
J. Woillez, W. M. Keck Observatory (United States)

Published in SPIE Proceedings Vol. 7734:
Optical and Infrared Interferometry II
William C. Danchi; Françoise Delplancke; Jayadev K. Rajagopal, Editor(s)

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