A New Orbit Determination for the Astrometric Binary Alpha Ophiuchi
Abstract
We present an improved orbit of the astrometric binary alpha Ophiuchi (V = 2.08, spectral class = A5 III), as derived by supplementing existing observational material from the Allegheny and Sproul Observatories covering the periods 193463 (A) and 194664 (S) with heretofore unmeasured Sproul plates covering the intervals 196567 and 198590. The combined data over 6 revolutions yield an orbit with P = 8.67 yr; the semimajor axis is alpha = 0."0.81 +/ 0."005. The Sproul data yielded an absolute parallax of pi_abs = +0."069 +/ 0."005, and the weighted mean of five independent determinations is pi_abs = +0."065 +/ 0."004. This gives an absolute magnitude of M_V = +1.2, which suggests that the more massive component of alpha Oph is a subgiant. (SECTION: Stars)
 Publication:

Publications of the Astronomical Society of the Pacific
 Pub Date:
 May 1992
 DOI:
 10.1086/132998
 Bibcode:
 1992PASP..104..314A
 Keywords:

 Astrometry;
 Binary Stars;
 Stellar Orbits;
 Orbit Calculation;
 Orbital Elements;
 Parallax;
 Astrophysics;
 BINARIES: VISUAL;
 ASTROMETRY