The angular diameter and fundamental parameters of sirius a

Abstract

The Sydney University Stellar Interferometer (SUSI) has been used to make a new determination of the angular diameter of Sirius A. The observations were made at an effective wavelength of 694.1nm and the new value for the limb-darkened angular diameter is 6.048 ± 0.040 mas (±0.66%). This new result is compared with previous measurements and is found to be in excellent agreement with a conventionally calibrated measurement made with the European Southern Observatory's Very Large Telescope Interferometer (VLTI) at 2.176m (but not with a second globally calibrated VLTI measurement). A weighted mean of the SUSI and first VLTI results gives the limb-darkened angular diameter of Sirius A as 6.041±0.017mas (±0.28%). Combination with the Hipparcos parallax gives the radius equal to 1.7130.009R⊙. The bolometric flux has been determined from published photometry and spectrophotometry and, combined with the angular diameter, yields the emergent flux at the stellar surface equal to (5.32±0.14) × 10 8Wm-2 and the effective temperature equal to 9845±64K. The luminosity is 24.7±0.7L⊙. © Astronomical Society of Australia 2011.