THE THREE-DIMENSIONAL ORBIT AND PHYSICAL PARAMETERS OF 47 OPH

Abstract

Although 47 Oph has been shown to be a binary with a period of similar to 27 days using both spectroscopic and interferometric techniques, only a preliminary orbit has been obtained in the previous work due to the shortage of high precision measurements. Since 1997, new spectroscopic and interferometric measurements have been obtained with much higher precision by the spectrograph of the 2.16 m telescope at Xinglong station and the Navy Precision Optical Interferometer, respectively. Combining all of the measurements, a three-dimensional orbit is obtained with high precision in this work. Thus, the component masses are calculated to be 1.50 +/- 0.06 and 1.34 +/- 0.06 M-circle dot, respectively. The orbital parallax is 32.6 +/- 0.6 mas, which is consistent with the Hipparcos parallax. With the known apparent magnitudes and color indices of the components, the derived luminosities are 7.80 +/- 0.36 and 3.41 +/- 0.25 L-circle dot. The estimated radii of the components are 2.06 +/- 0.07 and 1.36 +/- 0.06 R-circle dot. Finally, the evolutionary status of the components are investigated with the help of a stellar evolution model.