Where are all the Sirius-like binary systems?
Where are all the Sirius-like binary systems?
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DOI：
10.1093/mnras/stt1433
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发表时间：
2013-07
影响因子：
4.8
通讯作者：
J. Holberg;T. Oswalt;E. Sion;M. Barstow;M. Burleigh
中科院分区：
文献类型：
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作者：
J. Holberg;T. Oswalt;E. Sion;M. Barstow;M. Burleigh
附近大约70%的白矮星似乎是单星，其余的是双星或多星系统的成员。最多和最容易识别的系统是那些主序伴星是M星的系统，因为即使这些系统没有被分辨，白矮星在光学波长上要么主导着伴星的光度，要么至少与伴星的光度竞争。更难识别的系统是，非简并成分的光谱类型早于M0，而白矮星成为较弱的发光成分。以天狼星为原型，后一种系统在这里被称为类天狼星。目前已知的类天狼星系统有98个。在20秒内对当地白矮星群体的研究表明，大约8%的白矮星是类天狼星系统的成员，但在20秒之后，已知的类天狼星系统的频率下降到1%至2%之间，这表明还有更多的此类系统有待发现。估计了类天狼星系统的局部空间密度及其在A到K主序星的局部白矮星和局部白矮星群中的相对频率。目前尚未确定的天狼星类星系中的绝大多数很可能是紧密分离的、未解决的双星。讨论了对这些系统进行观测探测和研究的方法。
Approximately 70 percent of the nearby white dwarfs appear to be single stars, with the remainder being members of binary or multiple star systems. The most numerous and most easily identifiable systems are those in which the main sequence companion is an M star, since even if the systems are unresolved the white dwarf either dominates or is at least competitive with the luminosity of the companion at optical wavelengths. Harder to identify are systems where the non-degenerate component has a spectral type earlier than M0 and the white dwarf becomes the less luminous component. Taking Sirius as the prototype, these latter systems are referred to here as Sirius-Like. There are currently 98 known Sirius-Like systems. Studies of the local white dwarf population within 20 parsecs indicate that approximately 8 per cent of all white dwarfs are members of Sirius-Like systems, yet beyond 20 parsecs the frequency of known Sirius-Like systems declines to between 1 and 2 per cent, indicating that many more of these systems remain to be found. Estimates are provided for the local space density of Sirius- Like systems and their relative frequency among both the local white dwarf population and the local population of A to K main sequence stars. The great majority of currently unidentified Sirius-Like systems will likely turn out to be closely separated and unresolved binaries. Ways to observationally detect and study these systems are discussed.