TIME-SERIES SPECTROSCOPY OF TWO CANDIDATE DOUBLE DEGENERATES IN THE OPEN CLUSTER NGC 6633
TIME-SERIES SPECTROSCOPY OF TWO CANDIDATE DOUBLE DEGENERATES IN THE OPEN CLUSTER NGC 6633
复制标题
疏散星团 NGC 6633 中两个候选双简并星的时间序列光谱
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
P. Canton
中科院分区：
文献类型：
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作者：
K. Williams;Donald Serna;S. Chakraborty;A. Gianninas;P. Canton
超新星Ia是精密宇宙学中大量使用的工具，但我们仍然不确定祖先系统是什么。一般的似是而非的论证表明，在中年疏散星团中有可能发现双简并的SN Ia祖星。我们展示了疏散星团NGC 6633区域的两颗白矮星（WDs）的时间分辨高分辨率光谱，这两颗白矮星之前被确定为星团中的候选双简并星。然而，对每一个候选星系连续3小时的观测都没有发现任何显著的径向速度变化，在< 10 km s−1的水平上，这使得两个WD都不太可能是双简并星系，在哈勃时间内合并。NGC 6633 4的径向速度在2.5σ水平上与星团隶属度不一致，而NGC 6633 7的径向速度与星团隶属度一致。我们保守地得出结论，尽管不太可能是Ia型祖先，但LAWDS 7是一个可行的大质量双简并候选者。可能需要来自GAIA的天文测量数据来确定WD是否真的是一个星团成员。
SNe Ia are heavily used tools in precision cosmology, yet we still are not certain what the progenitor systems are. General plausibility arguments suggest there is potential for identifying double degenerate SN Ia progenitors in intermediate-age open star clusters. We present time-resolved high-resolution spectroscopy of two white dwarfs (WDs) in the field of the open cluster NGC 6633 that had previously been identified as candidate double degenerates in the cluster. However, three hours of continuous observations of each candidate failed to detect any significant radial velocity variations at the ≳10 km s−1 level, making it highly unlikely that either WD is a double degenerate that will merge within a Hubble Time. The WD LAWDS NGC 6633 4 has a radial velocity inconsistent with cluster membership at the 2.5σ level, while the radial velocity of LAWDS NGC 6633 7 is consistent with cluster membership. We conservatively conclude that LAWDS 7 is a viable massive double degenerate candidate, though unlikely to be a Type Ia progenitor. Astrometric data from GAIA will likely be needed to determine if either WD is truly a cluster member.