The angular diameter of R Doradus: a nearby Mira-like star

T.R. Bedding (1)(7), Albert A. Zijlstra (2), O. von der Lühe (2), J.G. Robertson (1),

R.G. Marson (1,3), J.R. Barton (4), B.S. Carter (5,6)



(1)School of Physics, University of Sydney 2006, Australia

(2)European Southern Observatory, Karl-Schwarzschild-strasse 2, D-85748 Garching bei München, Germany

(3)Current address: NRAO Array Operations Center, P.O. Box 0, Socorro NM 87801, USA

(4)Anglo-Australian Observatory, P.O. Box 296, Epping 2121, Australia

(5)South African Astronomical Observatory, P.O. Box 9, Observatory 7935, South Africa

(6)Current address: Carter Observatory, P.O. Box 2909, Wellington, New Zealand

(7)E-mail: bedding@physics.usyd.edu.au

Monthly Notices Royal Astronomical Society, in press (1997)

Abstract:

We find the angular diameter of R Doradus to be 57 +/- 5 mas, exceeding that of Betelgeuse and implying that R Dor is larger in apparent size than every star except the Sun. R Dor is shown to be closely related to the Mira variables. We estimate an effective temperature of 2740+/-190K, a distance of 61+/-7pc, a luminosity of 6500+/-1400 solar luminosities and a radius of 370+/-50 solar radii. The characteristics of R Dor are consistent with it being near the edge of a Mira instability strip. We detect non-zero closure phases from R Dor, indicating an asymmetric brightness distribution. We also observed W Hya, a small-amplitude Mira, for which we find an angular diameter of mas.




azijlstr@eso.org