| |
 |
| Paper: |
Multi-Epoch Mid-Infrared Interferometric Observations of the Oxygen-rich Mira Variable Star RR Aql with the VLTI/MIDI Instrument |
| Volume: |
445, Why Galaxies Care about AGB Stars II: Shining Examples and Common Inhabitants |
| Page: |
269 |
| Authors: |
Karovicova, I.; Wittkowski, M.; Boboltz, D. A.; Fossat, E.; Ohnaka, K.; Scholz, M. |
| Abstract: |
This work is part of an on-going program of multi-epoch
simultaneous observations
of a sample of four evolved stars — RR Aql, GX Mon, S Ori,
and AH Sco — using the VLTI and VLBA facilities. Different pulsating
layers and their relative positions are monitored across phases and
cycles. Here, we present mid-infrared interferometric observations
of the oxygen-rich Mira variable RR Aql at 13 epochs covering 4
pulsation cycles with the MIDI instrument at the VLTI. We
modeled the observed data using dust-free self-excited dynamic model
atmospheres combined with an ad-hoc radiative transfer model of
the dust shell. This study represents the first comparison between
interferometric observations and dynamic models over an extended
range of pulsation phases covering several cycles. We show that the
combination of the models describe the observed data well. We
determine the best dust-free dynamical model atmosphere and the
best dust shell parameters including the optical depth of the two
examined dust species (Al2O3 and silicates), the inner boundary
radii of the dust shells, the density distribution, and the continuum
photospheric angular diameter for all epochs. The results indicate
that silicate is the major chemical component in the dust shell.
We also compare the data with equivalent uniform disk (UD) and
Gaussian FWHM diameters. |
|
|
|
|
|
