Andrew J. Booth

Orbital parameters, masses and distance to β Centauri determined with the Sydney University Stellar: Interferometer and high-resolution spectroscopy

The bright southern binary star β Centauri (HR 5267) has been observed with the Sydney University Stellar Interferometer (SUSI) and spectroscopically with the European Southern Observatory Coude Auxiliary Telescope and Swiss Euler telescope at La Silla. The interferometric observations have confirmed the binary nature of the primary component and have enabled the determination of the orbital parameters of the system. At the observing wavelength of 442 nm the two components of the primary system have a magnitude difference of 0.15 ± 0.02. The combination of interferometric and spectroscopic data gives the following results: orbital period 357.00 ± 0.07 d, semimajor axis 25.30 ± 0.19 mas, inclination 67. ◦ 4 ± 0. ◦ 3, eccentricity 0.821 ± 0.003, distance 102.3 ± 1.7 pc, primary and secondary masses M 1 = ( ◦ )( ◦ ) .

Sydney University Stellar Interferometer

The Sydney University Stellar Interferometer (SUSI) is a long baseline optical interferometer located at the Paul Wild Observatory in northern New South Wales, some 400km NNW of Sydney. SUSI has been designed to measure the angular sizes of stars of essentially all spectral types and luminosity classes and to measure the angular separations of close binary stars. In addition to the science programs planned for SUSI, the technical features of the instrument dictated by these programs are discussed. The current status of the instrument and science programs, and the plans for further development of the instrument are described.

Progress in commissioning the Sydney University Stellar Interferometer (SUSI)

The Sydney University Stellar Interferometer (SUSI) is a long baseline optical amplitude interferometer. In its initial configuration it is a two aperture, single ro instrument with wavefront-tilt corrections and dynamic optical path length compensation. It has been designed to measure the angular dimensions of stars of essentially all spectral types as well as the angular separations of binary stars. SUSI is located alongside the Australia Telescope at the Paul Wild Observatory, near Narrabri in northern New South Wales, Australia. It has a North-South array of input stations giving baselines covering the range from 5 m to 640 m. The baselines are being progressively commissioned, starting with the shorter ones, in parallel with an observing program aimed at fine-tuning the performance of the instrument. Progress and results from the commissioning program and the current status of the instrument are described.

The Fringe Tracking Servo in Susi

We present a description of the pathlength compensation system used in the Sydney University Stellar Interferometer, and report on the method of fringe tracking that is being implemented. The components of this system are discussed, including the PAPA camera used to detect chromatic fringes, the fringe tracking servo, the delay line and its control.

An Overview of the Susi Control System

The SUSI control system is a distributed real-time system currently consisting of 17 processors. A custom real-time operating system and network protocols ensure synchronous operation of servo loops across multiple processors.

The Temperature Scale of the M Dwarfs

The effective temperature scale for M dwarfs is largely undetermined. We show that the VLTI can make a significant contribution to the data for these stars.