The double low-mass white dwarf eclipsing binary system J2102-4145 and its possible evolution
The double low-mass white dwarf eclipsing binary system J2102-4145 and its possible evolution
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双低质量白矮星食双星系统J2102-4145及其可能的演化
DOI：
10.1051/0004-6361/202348564
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发表时间：
2024
影响因子：
6.5
通讯作者：
Antunes Amaral L
中科院分区：
文献类型：
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作者：
Antunes Amaral L
近年来，大约有150颗低质量白矮星（WDs）被发现，通常质量低于0.4M⊙。这些低质量的WDs大多数是在双星系统中观测到的，因为它们不能在哈勃时间内通过单星演化形成。在这项工作中，我们对双低质量WD食双星系统J2102−4145进行了综合分析。我们的调查包括广泛的观测活动，导致使用NTT/ULTRACAM， SOAR/Goodman和SMARTS-1m望远镜在多个夜晚获得了大约28小时的高速光度数据。这些观测提供了对该系统轨道特性的重要见解，包括倾角和轨道周期等参数。为了解开J2102−4145的二元成分，我们利用GMOS/Gemini-South和X-shooter数据采用XTGRID光谱拟合方法。此外，我们使用PHOEBE软件包对NTT/ULTRACAM高速时间序列测光数据进行光曲线分析，以约束双星的性质。我们的分析揭示了这个双星系统的两个组成部分之间惊人的相似之处。对于主星，我们确定了K， logg1= 7.36±0.01,R1= 0.0211±0.0002R⊙,m1 = 0.375±0.003M⊙，而对于副星，我们确定了K， logg2= 7.32±0.01,m2 = 0.314±0.003M⊙。此外，我们发现teffandrof较小质量的WD与文献中WD的进化序列存在显著差异，这对我们对WD进化的理解具有重要意义。我们讨论了该系统的潜在形成场景，这可能解释这种差异并探索其未来的演变。我们预测这个系统将在~ 800 Myr合并，演变成一颗富含氦的热亚矮星，后来演变成一颗混合He/CO WD。
In recent years, about 150 low-mass white dwarfs (WDs), typically with masses below 0.4M⊙, have been discovered. The majority of these low-mass WDs are observed in binary systems as they cannot be formed through single-star evolution within Hubble time. In this work, we present a comprehensive analysis of the double low-mass WD eclipsing binary system J2102−4145. Our investigation encompasses an extensive observational campaign, resulting in the acquisition of approximately 28 h of high-speed photometric data across multiple nights using NTT/ULTRACAM, SOAR/Goodman, and SMARTS-1m telescopes. These observations have provided critical insights into the orbital characteristics of this system, including parameters such as inclination and orbital period. To disentangle the binary components of J2102−4145, we employed the XTGRID spectral fitting method with GMOS/Gemini-South and X-shooter data. Additionally, we used the PHOEBE package for light curve analysis on NTT/ULTRACAM high-speed time-series photometry data to constrain the binary star properties. Our analysis unveils remarkable similarities between the two components of this binary system. For the primary star, we determine K, logg1= 7.36 ± 0.01,R1= 0.0211 ± 0.0002R⊙, andM1= 0.375 ± 0.003M⊙, while, the secondary star is characterised by K, logg2= 7.32 ± 0.01, , andM2= 0.314 ± 0.003M⊙. Furthermore, we found a notable discrepancy betweenTeffandRof the less massive WD, compared to evolutionary sequences for WDs from the literature, which has significant implications for our understanding of WD evolution. We discuss a potential formation scenario for this system which might explain this discrepancy and explore its future evolution. We predict that this system will merge in ∼800 Myr, evolving into a helium-rich hot subdwarf star and later into a hybrid He/CO WD.