Complete text without figure (abstract only):
Dynamical parallaxes of visual binary stars with reliable orbits selected from the Multiple Star Catalogue [1] are compared with Hipparcos parallaxes. Data on 141 objects with Hipparcos parallax errors not exceeding 2.5 mas are divided into 3 groups according to the orbit quality and reliability of Hipparcos double-star solutions. These groups are: I. interferometric orbits (from speckle- or long-baseline interferometry); II. orbits from visual measurements (with »quality« not lower 3, see [2]); and III. unreliable Hipparcos double star solutions or suspected duplicity (cf. field H61 in [3]). Dynamical parallaxes are calculated with the use of a total system mass taking into account all known subsystems from [1]. Good agreement between dynamical and Hipparcos parallaxes is found for all distant systems (< 15 mas, see Fig. 1), but for intermediate-distance systems (from 15 to 30 mas) in some cases Hipparcos parallaxes have large errors caused by undetected short-period binaries. Hipparcos parallaxes in the third group do not show larger deviations from dynamical ones than for groups I and II. In 5 visual triples the parallaxes of the distant physical companions and of the orbital pairs are in good mutual agreement. So, we may conclude that Hipparcos parallaxes of multiple stars are of good quality if they do not contain close subsystems with periods of the order of 1 year.
References
[1] Tokovinin A.A., Astron. and Astrophys. Suppl. Ser., 1997, vol. 124, p. 75.
[2] Worley C.E., Heintz W.D., Publ. U.S. Naval Observ., 1983, vol. 24, Pt. 7.
[3] Hipparcos and Tycho catalogues. European Space Agency, 1997. SP-1200.
For Fig. 1 see p. 194 in the book.
Bibliographical details:
Nicolaj I. Shatsky, Andrei A. Tokovinin: Hipparcos versus dynamical parallaxes. In: Peter Brosche, Wolfgang R. Dick, Oliver Schwarz, Roland Wielen (Eds.): The Message of the Angles - Astrometry from 1798 to 1998. Proceedings of the International Spring Meeting of the Astronomische Gesellschaft, Gotha, May 11-15, 1998. (Acta Historica Astronomiae ; 3). Thun ; Frankfurt am Main : Deutsch, 1998, p. 193-194.
Html-Version: Wolfgang R. Dick. Created: 22 Jan 1999