EDP Sciences
Free access
Volume 431, Number 3, March I 2005
Page(s) 1019 - 1026
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20042013

A&A 431, 1019-1026 (2005)
DOI: 10.1051/0004-6361:20042013

The K-band intensity profile of R Leonis probed by VLTI/VINCI

D. Fedele1, 2, M. Wittkowski1, F. Paresce1, M. Scholz3, 4, P. R. Wood5 and S. Ciroi2

1  European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
    e-mail: mwittkow@eso.org
2  Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 2, 35122 Padova, Italy
3  Institut für Theoretische Astrophysik der Universität Heidelberg, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany
4  School of Physics, University of Sydney, NSW 2006, Australia
5  Research School for Astronomy and Astrophysics, Australian National University, Canberra, ACT 2600, Australia

(Received 15 September 2004 / Accepted 19 October 2004)

We present near-infrared K-band interferometric measurements of the Mira star R Leonis obtained in April 2001 and January 2002 with the VLTI, the commissioning instrument VINCI, and the two test siderostats. These epochs correspond to near-maximum stellar variability phases ~0.08 and ~1.02 (one cycle later), respectively. The April 2001 data cover a range of spatial frequencies (31-35 cycles/arcsecond) within the first lobe of the visibility function. These measurements indicate a center-to-limb intensity variation (CLV) that is clearly different from a uniform disk (UD) intensity profile. We show that these measured visibility values are consistent with predictions from recent self-excited dynamic Mira model atmospheres that include molecular shells close to continuum-forming layers. We derive high-precision Rosseland diameters of $28.5 \pm 0.4$ mas and $26.2 \pm 0.8$ mas for the April 2001 and January 2002 data, respectively. Together with literature estimates of the distance and the bolometric flux, these values correspond to linear radii of 350+50-40 $R_\odot$ and 320+50-40 $R_\odot$, and to effective temperatures of $2930 \pm 270$ K and $3080 \pm 310$ K, respectively.

Key words: techniques: interferometric -- stars: late-type -- stars: AGB and post-AGB -- stars: atmospheres -- stars: fundamental parameters -- stars: individual: R Leo

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© ESO 2005