Issue |
A&A
Volume 376, Number 2, September II 2001
|
|
---|---|---|
Page(s) | 518 - 531 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20010968 | |
Published online | 15 September 2001 |
Multi-wavelength bispectrum speckle interferometry of R Leo and comparison with Mira star models*
1
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2
Special Astrophysical Observatory, Nizhnij Arkhyz, Zelenchuk region, Karachai-Cherkesia, 357147, Russia
3
Institut für Theoretische Astrophysik der Universität Heidelberg, Tiergartenstr. 15, 69121 Heidelberg, Germany
4
Chatterton Department of Astronomy, School of Physics, University of Sydney NSW 2006, Australia
Corresponding author: K.-H. Hofmann, hofmann@mpifr-bonn.mpg.de
Received:
14
May
2001
Accepted:
28
June
2001
We present diffraction-limited (30 mas resolution) bispectrum
speckle interferometry of the Mira
star R Leo with the 6 m
SAO telescope.
The speckle interfero grams were recorded through narrow-band interference
filters with centre wavelength/bandwidth of 673 nm/8 nm
(strong TiO absorption band), 656 nm/10 nm, 699 nm/6 nm and 781 nm/14 nm (moderate TiO absorption),
754 nm/6 nm (weak TiO absorption), and 1045 nm/9 nm (continuum).
The reconstructed images show that the average uniform-disk diameters of
R Leo are 60.6 mas ± 3.0 mas at 656 nm, 75.6 mas ± 3.7 mas at 673 nm,
52.5 mas ± 2.5 mas at 699 nm, 48.7 mas ± 2.3 mas at 754 nm,
55.0 mas ± 2.7 mas at 781 nm, and 37.9 mas ± 4.0 mas at 1045 nm.
In all six observed wavelength bands the shape of R Leo shows no significant asymmetry.
We compare
our observations with Mira star models and check the
ability of monochromatic linear diameters for discriminating between
model representations of the observed star. Monochromatic
radii were derived from the observed visibilities
by application of
model-predicted center-to-limb variations of the intensity.
Adopting the HIPPARCOS parallax
we derived from the 1045 nm-observation a photospheric radius
(Rosseland
radius) of R Leo
of 417
(19.2 mas ± 2.0 mas)
indicating pulsation in the first-overtone mode.
From JHKL photometry and the angular photospheric radius an effective
temperature of
K at near maximum phase was obtained.
Key words: techniques: interferometric / methods: observational / stars: AGB and post-AGB / stars: imaging / stars: late-type / stars: variables: general / stars: individual: R Leo
© ESO, 2001
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