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Proceedings Paper

Well-resolved binary astrometry with the CHARA array
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Paper Abstract

Individually resolved packets produced by scans from the CHARA Interferometer Array for binary stars can be analyzed in terms of the astrometry of the binary without using visibilities. We considered various methods for finding the locations of the packets, including autocorrelation and Shift-and-Add, but our best results were obtained from a method of direct packet fitting. This method was put to use in analyzing two data sets each for the stars 12 Persei and Beta Arietis respectively. These data were taken between Nov 6 and 15, 2001 with the CHARA Array 330 m E1-S1 baseline. Some 460 to 830 scans were taken in both directions with the auxiliary PZT, and seeing conditions were fair to poor for these runs (r0 ≈ 7 cm). This procedure yielded a projected separation for each data set, with an intrinsic accuracy of 0.15 - 0.3 mas. This represents an order of magnitude improvement over speckle interferometry techniques. The orbits were refined by a maximum likelihood technique. In the case of 12 Per the semimajor axis obtained was α = 53.53 mas, compared with the previous orbit of 53.38 mas, a small increase of 0.27%, which implies a mass increase of 0.8%, an insignificant change for this well-established orbit. For Beta Arietis, we find that α = 35.62 versus the previous orbit's value of 36.00 mas. This is a 1.0% decrease, resulting in a mass decrease of 3.0% for this system.

Paper Details

Date Published: 21 February 2003
PDF: 7 pages
Proc. SPIE 4838, Interferometry for Optical Astronomy II, (21 February 2003); doi: 10.1117/12.459078
Show Author Affiliations
William G. Bagnuolo, CHARA/Georgia State Univ. (United States)
Theo Armand ten Brummelaar, CHARA Array/Mt. Wilson (United States)
Harold A. McAlister, CHARA/Georgia State Univ. (United States)
Nils Henning Turner, CHARA Array/Mt. Wilson (United States)
Laszlo Sturmann, CHARA Array/Mt. Wilson (United States)
Judit Sturmann, CHARA Array/Mt. Wilson (United States)
Stephen T. Ridgway, CHARA Array/Mt. Wilson (United States)

Published in SPIE Proceedings Vol. 4838:
Interferometry for Optical Astronomy II
Wesley A. Traub, Editor(s)

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