Collinder 261 中短周期蓝离散星的起源：双星演化途径

中文摘要 AI 辅助

基于近期利用 Gaia DR3 数据发布的银河系疏散星团蓝离散星新星表，我们开展了一项研究，聚焦于疏散星团 Collinder 261 中发现的具有短周期光变性的蓝离散星：9 颗食双星或椭球双星，以及 5 颗 SX Phe 脉动候选体。我们的研究深入探讨了双星系统中的质量转移在解释这些恒星的存在及其性质方面的潜力。我们首先测量了它们的光度周期，并将这些变星分类为食双星/椭球双星、SX Phe 脉动候选体，以及仪器假频或混合体。随后，我们基于对双星系统内两颗恒星结构的全面计算，以及它们的轨道演化和质量转移速率，进行了一系列模拟。为了与观测进行比较，我们求解了每个恒星组分的大气结构，并计算了 Gaia DR3 波段中经滤光片加权的积分通量，从而获得了一个组合演化序列，该序列解释了从光度观测中所见的双星未分辨通量。我们的研究涵盖了对多个参数的探讨，例如两颗恒星的初始质量、初始轨道周期以及质量转移效率。其目的是识别出与 Collinder 261 所确定的年龄相同的颜色-星等图观测相匹配的潜在前身星候选体。我们发现，双星演化可作为产生这些食蓝离散星的可行机制，且质量转移效率在精确匹配较暗天体方面起着关键作用。

英文摘要

Building on the recent publication of a fresh catalog of blue straggler stars in Galactic open clusters using Gaia DR3, we conduct a study focusing on the blue straggler stars with short-period photometric variability found in the open cluster Collinder 261: nine eclipsing or ellipsoidal binaries and five SX Phe pulsator candidates. Our investigation delves into the potential of mass transfer in binary systems to account for the presence and properties of these stars. We first measure their photometric periods and classify the variables into eclipsing/ellipsoidal binaries, SX Phe pulsator candidates, and instrumental aliases or blends. Subsequently, we perform a set of simulations based on comprehensive calculations of the structure of both stars within the binary system, as well as their orbital evolution and mass transfer rates. To compare with observations, we solved the atmospheric structure of each stellar component and computed filter-weighted integrated fluxes in the Gaia DR3 passbands, obtaining a combined evolutionary sequence that accounts for the unresolved flux of both stars as seen photometrically. Our investigation includes the study of several parameters, such as the initial mass of both stars, the initial orbital period, and the efficiency of mass transfer. The aim is to identify potential progenitor candidates matching color-magnitude diagram observations at the same age as that determined for Collinder 261. We find that binary evolution serves as a viable mechanism for producing these eclipsing blue stragglers and that the efficiency of mass transfer plays a key role in accurately matching the fainter objects.

发表机构

• Instituto de Astrofísica de La Plata, IALP (CONICET-UNLP)（拉普拉塔天体物理研究所（IALP，CONICET-UNLP））
• INAF – Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所–阿尔切特里天体物理天文台）
• European Southern Observatory（欧洲南方天文台）
• Università di Padova（帕多瓦大学）
• Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata (UNLP)（拉普拉塔国立大学天文与地球物理学院）

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