EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 376/2 Article
Free access article

Issue A&A
Volume 376, Number 2, September II 2001
Page(s) 518 - 531
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20010968



A&A 376, 518-531 (2001)
DOI: 10.1051/0004-6361:20010968

Multi-wavelength bispectrum speckle interferometry of R Leo and comparison with Mira star models

K.-H. Hofmann1, Y. Balega2, M. Scholz3, 4 and G. Weigelt1

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

(Received 14 May 2001 / Accepted 28 June 2001)

Abstract
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 $\pm$ 3.0 mas at 656 nm, 75.6 mas $\pm$ 3.7 mas at 673 nm, 52.5 mas $\pm$ 2.5 mas at 699 nm, 48.7 mas $\pm$ 2.3 mas at 754 nm, 55.0 mas $\pm$ 2.7 mas at 781 nm, and 37.9 mas $\pm$ 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 $\tau_{\lambda}=1$ 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 $\tau_{\rm Ross}=1$ radius) of R Leo of 417 $R_{\odot} \pm 97 R_{\odot}$ (19.2 mas $\pm$ 2.0 mas) indicating pulsation in the first-overtone mode. From JHKL photometry and the angular photospheric radius an effective temperature of $2590 \pm 180$ 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

Offprint request: K.-H. Hofmann, hofmann@mpifr-bonn.mpg.de

SIMBAD Objects in preparation



© ESO 2001


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.