Publications of the MPIfR
Optical & Infrared
Interferometry Group
K. Ohnaka, J. Bergeat, T. Driebe, U.
Graser, K.-H. Hofmann, R. Köhler, Ch. Leinert, B. Lopez, F. Malbet, S.
Morel, F. Paresce, G. Perrin, Th. Preibisch, A. Richichi,
D. Schertl,
M. Schöller, H. Sol, G. Weigelt, M. Wittkowski
The circumstellar environment of evolved stars
as seen by VLTI/MIDI
"ESO Astrophysics Symposia"
Proceedings of the ESO Workshop: "The power of
optical/IR interferometry: recent scientific results and 2nd generation
VLTI instrumentation"
April 4-8, 2005 in Garching, Germany
pg.111-115 (2008)
Abstract
We present the results of the first mid-infrared interferometric
obser vations of the Mira variable RR Sco with the VLTI/MIDI, together
with K-band observations using VLTI/VINCI. The uniform-disk diameter
was found to be 18 mas between 8 and 10 µm, while it gradually
increases at wavelengths longer than 10 µm to reach 24 mas at 13 µm.
These uniform-disk diameters in the mid-infrared are significantly
larger than the K-band uniform-disk diameter of 10.2±0.5 mas measured
using VLTI/VINCI, three weeks after the MIDI observations. Our model
calculations show that optically thick emission from a warm molecular
envelope consisting of H2O and SiO can cause the apparent mid-infrared
diameter to be much larger than the continuum diameter, and this can
explain the mid-infrared angular sizes roughly twice as large as that
measured in the K band. The observed increase of the uniform-disk
diameter longward of 10 µm can be explained by an optically thin dust
shell consisting of corundum and silicate grains.
You can get this publication ...