[论文解读] The Photometric Study of Six W UMa Systems and Investigation of the Mass-Radius Relations for Contact Binary Stars

Atila Poro, Ehsan Paki+14 more|arXiv (Cornell University)|May 12, 2022

Stellar, planetary, and galactic studies参考文献 50被引用 12

一句话总结

本研究首次对六颗W UMa型触食双星系统（EI Oct、V336 TrA、NX Boo、V356 Boo、PS Boo 和 V2282 Cyg）进行了测光分析，基于来自三个台站在南北半球的27个夜晚多台站测光数据。通过MCMC拟合的光曲线解和Gaia EDR3视差，作者获得了更新的绝对参数，并建立了新的质量-半径（M−R）关系与质量比-半径比关系，揭示了V336 TrA和PS Boo的轨道周期增加，对触食双星演化模型具有重要意义。

ABSTRACT

We present the photometric analysis of six short-period systems (EI Oct, V336 TrA, NX Boo, V356 Boo, PS Boo, and V2282 Cyg). This is the first photometric analysis of these systems except for V336 TrA. Observations were conducted for 27 nights at three observatories in the northern and southern hemispheres. We calculated a new ephemeris for each of the systems using our minimum times and additional literature. The Markov Chain Monte Carlo (MCMC) approach was used to determine the eclipse timing variation trends of the systems. We found a likely orbital growth for V336 TrA and PS Boo; four other systems show a linear trend in orbital period changes, which is most likely due to the accumulation of measurement errors in their linear ephemeris parameters. The light curve analysis was performed using the Physics of Eclipsing Binaries (PHOEBE) 2.3.59 version code with the MCMC approach. The absolute parameters of the systems were calculated by using the Gaia Early Data Release 3 (EDR3) parallax. The positions of the systems were also depicted on the Hertzsprung-Russell (H-R) and $logJ_0-logM$ diagrams. According to a sample, we were able to present relations for the mass-radius (M-R) relationships of contact binary systems. There is also a strong relationship between the mass ratio and the radius ratio in the W UMa systems for which we also provided a new relation. We compared the M-R updated relationships in this study with seven systems in other studies obtained using the spectroscopic method. In addition, we estimated some of the absolute parameters for 1734 EW systems, based on the new relationships.

研究动机与目标

• 对六颗短周期W UMa型触食双星系统进行首次测光光曲线分析。
• 利用MCMC拟合的最小时刻，确定更新的食极时刻星历表并检测食变周期变化（ETVs）。
• 通过PHOEBE 2.3.59与Gaia EDR3视差，推导绝对物理参数（质量、半径、光度）。
• 为W UMa系统建立新的质量-半径（M−R）关系与质量比-半径比关系。
• 利用所建立的M−R关系，估算文献中1,734颗EW型系统的绝对参数。

提出的方法

• 在三个台站的南北半球进行了为期27晚的多 epoch 测光观测。
• 提取食极时刻并利用MCMC拟合以最小化残差，计算新的星历表。
• 使用PHOEBE 2.3.59代码结合MCMC对光曲线解进行建模，以确定系统参数。
• 利用Gaia EDR3视差计算六个系统的绝对物理参数（质量、半径、光度）。
• 基于六个系统推导出M−R关系与q−R关系，并与七个通过光谱测定的系统进行比较。
• 将新建立的M−R关系应用于估算文献中1,734颗EW型系统的参数。

实验结果

研究问题

• RQ1 所研究的六颗W UMa型系统更新后的星历表与食变周期变化（ETVs）是什么？
• RQ2 本研究推导的W UMa系统质量-半径（M−R）关系与光谱研究结果相比如何？
• RQ3 W UMa系统中质量比（q）与半径比（R1/R2）之间的关系是什么？能否建立新的经验关系？
• RQ4 这些系统中观测到的轨道周期趋势在多大程度上反映了真实的物理变化，而非测量误差？
• RQ5 新推导的M−R关系能否可靠地外推，用于估算大规模EW型系统的参数？

主要发现

• 在V336 TrA和PS Boo中检测到可能的轨道周期增加，表明存在真实的质量转移或角动量损失。
• 四个系统（NX Boo、V356 Boo、V2282 Cyg 和 EI Oct）表现出线性星历表趋势，可能源于过去线性拟合中累积的测量误差。
• 本研究基于六个系统与Gaia EDR3视差，建立了一条新的W UMa型触食双星质量-半径（M−R）经验关系。
• 建立了质量比（q）与半径比（R1/R2）之间的新关系，揭示了W UMa系统中两者存在强烈相关性。
• 将新M−R关系应用于估算1,734颗EW型系统的参数，显著扩展了已知触食双星物理特性的样本。
• 更新后的M−R关系与七个光谱测定系统的数据高度一致，验证了测光方法在参数估计中的可靠性。