几乎相接的早型半接双星Tx Cas的uvby四色测光

FOUR COLOR uvby PHOTOMETRY OF THE ALMOST CONTACT SEMI-DETACHED SYSTEM TX CASSIOPEIAE

作者于1984年10月—1985年1月,对早型食双星TX Cas(P=2.9268天)进行了uvby四色观测,得到其光度极大时的色星等和色指数为v=9.15,b-y=0.33,m_1=-0.02,c_1=0.27和u-b=0.90.星际红化量E(b-y)=0.43.由测光解表明,TX Cas是一颗几乎相接的半接双星,质比q=m_2/m_1=0.304,其小质量次子星充满Roche临界面,而大质量的主子星接近充满Roche临界面.本文认为TX Cas是由光谱型大约为B1.5+B7的两子星组成的早型系统.可能属于Cas B质量交流的公共壳演化阶段之后的双星.

The early-type eclipsing binary TX Cas was observed in the Stromgren uvby system from October, 1984 to January, 1985. In total 343 pairs of b and y observations, among which 126 pairs including u and v observations at the same time, were obtained covering the whole orbital phase with a new determined period p=.2.9268352 days. The color indices of TX Cas at the maximum light were found to be v=9.15, b-y=0.33, m_1=-0.02, c_1=0.27 and u-b=0.90, and the reddening E (b—y)=0.43. With the Wilson-Devinney program of 1983 edition, the v, b, and y light curves were analysed simultaneously. It is revealed that TX Cas is an almost contact semi-detached system with the less massive component filling its Roche lobe and the massive one nearly in contact with it, The photometric mass ratio was found to be q=m_2/m_1=0.304 and the temperatures of components to be T_1= 24,500° K and T_2=14,770° K, respectively. TX Cas probably consists of two early-type components of spectral type B1.5+B7. The system may be just after the common evelope evolutionary stage of Cas B mass transfer.