AI 中文总结
研究利用VLTI/PIONIER干涉测量WR 25，首次分辨出其三个天体，确定了内部双星的角间距、半长轴及质量等参数，还探测到第三颗恒星并得出其相关参数，确认其三体性质，使其成为重要基准系统。
AI 中文摘要
WR 25是船底座星云里一个大质量碰撞风双星系统，由一颗WN6ha主星和一颗O5伴星组成，轨道偏心，周期208天。近期光谱分析估计其总质量近100太阳质量，主星与伴星质量比约为2。有迹象表明存在第三颗侵入恒星，使其成为候选层级三体系统。本研究首次通过VLTI/PIONIER干涉测量对WR 25进行观测，分辨出所有三个天体。对于内部的WN6ha+O5双星，角间距为1.68±0.02毫角秒，据此确定半长轴a=3.11±0.20天文单位，新约束的双星总动力学质量为93±18太阳质量，主星质量M1=62±13太阳质量，伴星质量M2=31±7太阳质量。还探测到第三颗恒星，与主星角间距为27.69±0.02毫角秒，对齐概率低于10^-4。利用新得到的各天体亮度比，重新分析WR 25的光谱数据，得出第三颗恒星光谱型为O7，与内部双星同龄，演化质量M3=25.6^+2.8_-2.3太阳质量。基于模拟，估计第三颗恒星周期在19 - 82年之间。WR 25新确认的三体性质使其成为测量内部双星乃至第三颗恒星精确动力学质量、校准恒星演化和大气模型、研究其作为层级三体系统的形成与稳定性的重要基准系统。
英文摘要
WR 25 is a massive colliding-wind binary in the Carina nebula comprising a WN6ha primary with an O5 companion in an eccentric 208-d orbit. Recent spectroscopic analysis estimates the total binary mass to approach $100\,M_\odot$, and a primary-to-secondary mass ratio of $q= M_1/M_2\approx2$. The presence of additional spectroscopic signatures from a third, intruder star was also noted, making it a candidate hierarchical triple system. In this study, we present a VLTI/PIONIER interferometric observation of WR 25, spatially resolving all three components for the first time. For the inner WN6ha + O5 binary, we find an angular separation of $1.68\pm0.02$ milliarcseconds (mas). Leveraging the fortunate timing of the VLTI observation, which was obtained when the two components were passing the line of nodes, we determined the semi-major axis $a=3.11\pm0.20$ au. Subsequently, the newly constrained total dynamical binary mass is $93\pm18\,M_\odot$, with a primary mass $M_1=62\pm13\, M_\odot$ and secondary mass $M_2=31\pm7\, M_\odot$. We detect the tertiary with an angular separation of $27.69\pm0.02$ mas from the primary, with a chance alignment probability lower than $10^{-4}$. Using newly obtained brightness ratios between all components, we revisit archival spectroscopic data of WR 25 to disentangle spectra for individual components and derive their stellar parameters. The tertiary, which has a spectral type O7, is coeval with the inner binary and has an evolutionary mass $M_3=25.6^{+2.8}_{-2.3}\,M_\odot$. Based on simulations, we estimate the tertiary period to be in the range 19 - 82 yr. The newly confirmed triple nature of WR 25 makes it an important benchmark system to measure accurate dynamical masses of the inner binary and potentially the tertiary, to calibrate stellar evolution and atmosphere models, and to study its formation and stability as a hierarchical triple system.
Comments9 pages, 7 figures. Accepted for publication in Astronomy & Astrophysics
