TY - JOUR
T1 - JHK'-band IOTA interferometry of the circumstellar environment of R CrB
AU - Ohnaka, K.
AU - Beckmann, U.
AU - Berger, J.-P.
AU - Brewer, M. K.
AU - Hofmann, K.-H.
AU - Lacasse, M. G.
AU - Malanushenko, V.
AU - Millan-Gabet, R.
AU - Monnier, J. D.
AU - Pedretti, E.
AU - Schertl, D.
AU - Schloerb, F. P.
AU - Shenavrin, V. I.
AU - Traub, W. A.
AU - Weigelt, G.
AU - Yudin, B. F.
PY - 2003/9/1
Y1 - 2003/9/1
N2 - We report the first long-baseline interferometry of the circumstellar
dust environment of R CrB. The observations were carried out with the
Infrared Optical Telescope Array (IOTA), using our new JHK' beam
combiner which enables us to record fringes in the J, H, and K' bands
simultaneously. The circumstellar dust envelope of R CrB is resolved at
a baseline of 21 m along a position angle of ~ 170deg, and
the visibilities in the J, H, and K' bands are 0.97 +/- 0.06, 0.78 +/-
0.06, and 0.61 +/- 0.03, respectively. These observed visibilities,
together with the K'-band visibility obtained by speckle interferometry
with baselines of up to 6 m, and the spectral energy distribution are
compared with predictions from spherical dust shell models which consist
of the central star and an optically thin dust shell. The comparison
reveals that the observed J- and H-band visibilities are in agreement
with those predicted by these models, and the inner radius and inner
boundary temperature of the dust shell were derived to be 60-80
Rstar and 950-1050 K, respectively. However, the predicted
K'-band visibilities are found to be ~ 10% smaller than the one
obtained with IOTA. Given the simplifications adopted in our models and
the complex nature of the object, this can nevertheless be regarded as
rough agreement. As a hypothesis to explain this small discrepancy, we
propose that there might be a group of newly formed dust clouds, which
may appear as a third visibility component.
AB - We report the first long-baseline interferometry of the circumstellar
dust environment of R CrB. The observations were carried out with the
Infrared Optical Telescope Array (IOTA), using our new JHK' beam
combiner which enables us to record fringes in the J, H, and K' bands
simultaneously. The circumstellar dust envelope of R CrB is resolved at
a baseline of 21 m along a position angle of ~ 170deg, and
the visibilities in the J, H, and K' bands are 0.97 +/- 0.06, 0.78 +/-
0.06, and 0.61 +/- 0.03, respectively. These observed visibilities,
together with the K'-band visibility obtained by speckle interferometry
with baselines of up to 6 m, and the spectral energy distribution are
compared with predictions from spherical dust shell models which consist
of the central star and an optically thin dust shell. The comparison
reveals that the observed J- and H-band visibilities are in agreement
with those predicted by these models, and the inner radius and inner
boundary temperature of the dust shell were derived to be 60-80
Rstar and 950-1050 K, respectively. However, the predicted
K'-band visibilities are found to be ~ 10% smaller than the one
obtained with IOTA. Given the simplifications adopted in our models and
the complex nature of the object, this can nevertheless be regarded as
rough agreement. As a hypothesis to explain this small discrepancy, we
propose that there might be a group of newly formed dust clouds, which
may appear as a third visibility component.
M3 - Article
SN - 1286-4846
VL - 408
SP - 553
EP - 558
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
ER -