Well-resolved binary astrometry with the CHARA array

William G. Bagnuolo Jr.; Theo Armand ten Brummelaar; Harold A. McAlister; Nils Henning Turner; Laszlo Sturmann; Judit Sturmann; Stephen T. Ridgway

doi:10.1117/12.459078

21 February 2003 Well-resolved binary astrometry with the CHARA array

William G. Bagnuolo Jr., Theo Armand ten Brummelaar, Harold A. McAlister, Nils Henning Turner, Laszlo Sturmann, Judit Sturmann, Stephen T. Ridgway

Author Affiliations +

Proceedings Volume 4838, Interferometry for Optical Astronomy II; (2003) https://doi.org/10.1117/12.459078
Event: Astronomical Telescopes and Instrumentation, 2002, Waikoloa, Hawai'i, United States

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.

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William G. Bagnuolo Jr., Theo Armand ten Brummelaar, Harold A. McAlister, Nils Henning Turner, Laszlo Sturmann, Judit Sturmann, and Stephen T. Ridgway "Well-resolved binary astrometry with the CHARA array", Proc. SPIE 4838, Interferometry for Optical Astronomy II, (21 February 2003); https://doi.org/10.1117/12.459078

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