Multi-Wavelength Visibility Observations of Circumstellar Material with the Keck Interferometer
Dr. William C. Danchi, NASA/Goddard Space Flight Center
We propose a series of Fringe Visibility Science observations with the Keck Interferometer. These observations are based on successfully programs with aperture masking at the Keck I telescope and with the U.C. Berkeley Infrared Spatial Interferometer. These observations will be used to
(1) test and validate the performance of the Keck Interferometer;
(1) develop a set of useful tools and procedures to enable a broad range of astronomers to successfully use the Keck Interferometer;
(2) provide exciting new science with a minimum of risk and maximum payoff.
Stellar Astronomy with the Keck Interferometer
Shrinivas R. Kulkarni, Caltech
We propose to join the instrument teams in commissioning the Keck Interferometer (KI). Several key areas-the distance and age of the Universe, the masses of planets-are stymied by inadequate stellar models, which can be traced to a poor treatment of convection. Recent 3-D convection codes appear promising. We propose a program of visibility measurements of binaries-eclipsing, in nearby clusters, Cepheid primaries-which may allow us to observationally gain confidence in these models and immediately publishable results. The novel Differential Phase (DP) mode opens new frontiers with the goal of direct detection of hot Jupiters. We propose a graduated astronomical program for DP with the goal of using astronomical redundancy to empirically measure the sensitivity of DP.
Resolving Young Stellar Objects on sub-AU Scales: the Inner Accretion
Disks of T Tauri and Herbig Ae/Be Stars
John Monnier, Harvard-Smithsonian Center for Astrophysics
Rafael Millan-Gabet, Harvard-Smithsonian Center for Astrophysics
The commissioning of the Keck Interferometer represents a radical
advance in the scientific capabilities of infrared interferometry, the
first step toward an expected 500-fold increase in sensitivity over
the best current facilities. We propose to take immediate advantage
of the initial improved sensitivity and the milli-arcsecond resolution
to resolve disks around young stellar objects on sub-AU scales,
allowing a large sample of young solar analogues to be observed for
the first time. When combined with detailed radiative transfer
modeling, the near-IR sizes measured by the Keck Interferometer will
reveal the geometry and physical conditions of the inner regions of
accretion disks for T Tauri and nearby Herbig Ae/Be systems with
unprecedented clarity. Our survey is designed to resolve the mystery
of the "large" near-IR disks uncovered by the current generation of
interferometer (IOTA/PTI), by studying the fundamental physical
properties of accretion disks and how they vary as a function of
stellar luminosity, total disk mass, age, and multiplicity. We show
that our observations will also be sensitive enough to detect inner
disk evolution in T Tauri systems, an indicator of early planetary
formation. An essential function of our survey will also be to fully
characterize the calibration stability and sensitivity of the Keck
Interferometer (with JPL) and to aid in establishing and validating
the fringe science data pipeline (with IPAC-MSC).
Circumstellar disk detection with the Keck Nuller
Wesley A. Traub, Smithsonian Astrophysical Observatory (PI)
Marc J. Kuchner, Harvard-Smithsonian Center for Astrophysics (CoPI)
The Keck Nuller must measure the exozodiacal dust emission around nearby stars to help determine a strategy for the Terrestrial Planet Finder (TPF) mission. It can also provide a first glimpse at the central 20 milliarcseconds of known circumstellar disks, and offer the first opportunity to resolve protoplanetary disks around T Tauri stars in the mid-infrared. We propose a program of modeling and testing the interferometer to learn how to interpret nuller data and to calibrate its systematics. Our goal is to establish confidence in the nuller's ability to detect circumstellar dust down to the level of 10 times the solar zodiacal cloud, seen at 10 pc, so that a large scale survey for exozodiacal dust can proceed. Once we have developed an understanding of the behavior of the instrument, we will progress towards the TPF survey by targeting stars with optically thick circumstellar disks, working our way downward in optical depth and expected signal, from T Tauri and Herbig Ae stars to Vega-like stars to a mini-survey of a small subset of the TPF target list. We will plan a full survey of the nearly 100 accessible TPF target stars to complete with additional years of Keck Nuller time.
