HD15020很可能是较长周期的双星

HD105020 PROBABLY IS A BINARY WITH A PERIOD OF ABOUT TWENTY DAYS

HD105020被Archer声称是周期只有两天的大陵五型双星,主星为K型,若能确认如此晚的子星组成周期这样短的双星,意义是非常重大的。1984年,用美国McDonald天文台2.1米望远镜Reticon系统进行了三夜共21次观测,1991年用Kitt Peak天文台的2.1米望远镜的T13 CCD系统进行了两夜共三次观测,得出:(1)因相近几夜的视向速度变化小,自转速度小,不可能是周期只有两天的大陵五型双星;(2)不同时期获得的视向速度有明显变化,很可能是周期为20天左右的分光双星。

HD105020(SAO 08216) was announced bv Archer (1959) as a new Algol type binary with a period about two days; the eclipse depthes of its primary and secondary minima are 1.7 and 0.3 mag., respectively. The spectral type of the primary is K. Wood et al. (1980) pointed out that it is a very important binary for evolution of cool stars if confirmed. Twenty one observations were made with Coude Reticon attached to the 2.1-m telescope at McDonald Observatory in 17—19, Jan. 1984. Three data were obtained by Coude T13 CCD of 2.1-m telescope at Kitt. Peak Observatory in 13—14 June 1991, with the dispersion of 14.8A/mm. The radial velocities from these data are listed in Table 1. Compiling and analysing the previous results by Heard (1956, 1965), we conclude that HD105020 is a binary with a period of about 20 days instead of 2 days. More observations are needed for covering the complete spectroscopic orbital revolution. The authors are greatly indebted to H. J. Smith, the former Director of McDonald Observatory, and to S. C. Wolff, the Director of NOAO, for schduling the telescope time for us; we are also grateful to R. H Koch for his helpful discussion.