Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
Visibilities of o Cet vs. spatial frequency
H.C. Woodruff, M. Eberhardt, T. Driebe, K.-H. Hofmann,
K. Ohnaka, A. Richichi, D. Schertl, M. Schoeller, M. Scholz, G.
Weigelt, M. Wittkowski, and P.R. Wood
Interferometric observations of the Mira star o
Ceti with the VLTI/VINCI instrument in the near-infrared
Astronomy and Astrophysics, v.421, p. 703-714
(2004)
Abstract.
We present K-band commissioning observations of the Mira star prototype
o Cet
obtained at the ESO Very Large Telescope Interferometer (VLTI)
with the VINCI instrument and two siderostats.
The observations were carried out between 2001 October and December, in
2002 January and December,
and in 2003 January. Rosseland angular radii are derived from the
measured visibilities
by fitting theoretical visibility functions obtained from
center-to-limb intensity variations
(CLVs) of Mira star models.
Using the derived Rosseland angular radii and the SEDs reconstructed
from available photometric
and spectrophotometric data, we find effective temperatures
ranging from Teff = 3192 +- 200 K at phase Phi=0.13 to 2918 +- 183 K at
Phi=0.26.
Comparison of these Rosseland radii, effective temperatures, and the
shape of the observed
visibility functions with model predictions suggests that o Cet is a
fundamental mode pulsator.
Furthermore, we investigated the variation of visibility function and
diameter with phase.
The Rosseland angular diameter of o Cet increased from 28.9 +- 0.3 mas
(corresponding to a Rosseland radius of 332 +- 38 Rsun for a distance
of D=107 +- 12 pc)
at Phi=0.13 to 34.9 +- 0.4 mas 402 +- 46 Rsun at Phi=0.4.
The error of the Rosseland linear radius almost entirely results from
the error of the parallax,
since the error of the angular diameter is only approximately 1%.
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