NSVS 2569022: a peculiar binary among W UMa stars with extremely small mass ratios

• 来源期刊: 天文和天体物理学研究
• 年，卷（期）: 2018,（10）
• 页码范围: 123-130
• 页数: 8页
• 语种: 英文
• DOI: 10.1088/1674-4527/18/10/129

摘要

Photometric observations of the W UMa binary NSVS 2569022 are presented.The light curve solution reveals that both components are of F spectral type (temperatures T1 =T2 =6100 K).NSVS 2569022 undergoes a total eclipse of W subtype and the mass ratio is well-determined.Its extremely small value of only 0.077 implies that the target will probably experience instability and a possible merger.This value ranks NSVS 2569022 in sixth place among binaries with the smallest mass ratio.Based on an empirical relation of "period-total mass" for low mass-ratio binaries,we estimate the global parameters of NSVS 2569022:masses M1 =1.17 M☉ and M2 =0.09 M☉;radii R1 =1.19 R☉ and R2 =0.38 R☉;luminosities L1 =1.73 L☉ and L2 =0.17 L☉.An analysis of the characteristics of binaries with extremely low-mass ratios is made.NSVS 2569022 turns out to be a peculiar binary among W UMa stars with extremely small mass ratios due to its unexpectedly small fill-out factor of only 0.014 (slightly overcontact configuration).