Canopus Angular Diameter Revisited by the AMBER Instrument of the VLT Interferometer
Bendjoya, P.; Domiciano de Souza, A.; Vakili, F.; Millour, F.; Petrov, R.
The Eighth Pacific Rim Conference on Stellar Astrophysics: A Tribute to Kam-Ching Leung
Proceedings of the conference held 5-9 May, 2008, at Merlin Beach Hotel, Phuket, Thailand.
Edited by B. Soonthornthum, S. Komonjinda, K.S. Cheng, and K.C. Leung
San Francisco: Astronomical Society of the Pacific Conference Series, Vol. 404, p.330 (2009)
Abstract
We used the VLTI/AMBER instrument to obtain interferometric data on the F0I star Canopus (visibilities and closure phases in the H and K bands with spectral resolution of 35). The
adopted baselines (100 m) and the high quality of the VLTI/AMBER observations allowed us to measure fringe visibilities up to the third visibility lobe of Canopus.The angular
diameter has been measured from the visibility and set to be (6.95 ± 0.15) mas. From this measured angular diameter we derive a stellar radius R=(72± 4) Rsun and an effective
temperature Teff=(7272± 107) K or Teff=(7570± 250) K depending on the considered bolometric flux and its precision. Contrarily to the theory, our VLTI/AMBER data do not reveal any
limb darkening on Canopus in the near-IR. Our observations set new constraints on the physical parameters of this star.
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