行星状星云NGC2346核星的食光变现象的消失

The Drastic Disappearance of Eclipses in the Central Star of the Planetary Nebula NGC 2345

本文给出了对行星状星云NGC2346核星AGK3—0°695从1981年到1987年这段期间内所做的照相观测结果。从中我们看到该天体自1981年底开始出现的大变幅食光变现象持续数年之后,从1986年开始其光变幅度迅速减小,由85年的Δm～4~m减小到86年的Δm～1~m.1。而且到1987年其光变曲线仅存Δm～0~m.4的不规则亮度起伏,已无明显的周期性光变现象,文中对此现象做了初步分析讨论。

In this paper we present photographic photometry of NGC 2346 from 1981 to 1987. The results are given in tables 1 and 2. The photographic light curves we obtained in 1985, 1986 and 1987 are plotted in Figure 1. From these observations we find that the brightness variations of the central star of NGC 2346 changed substantially from 1985 to 1987. The eclipse amplitude was decreasing rapidly, changing from 4.0 mag (1985) and 1.1 mag (1986) to about 0.4 mag (1987). And in the light curve of 1987 we could not see the eclipse variations again. The prominent eclipse variations of the nucleus of NGC 2346 which started from 1981 Nov. disappeared in 1987. But they could reappear with another matter ejection or outburst by the subdwarf O star in the future. The paper is concluded with a discussion on the nature of this startling event.