Multiplicity of stars as a function of mass

虽然通常认为大多数恒星是以双星形式形成的，但最近对低质量恒星的研究表明，M型、L型和T型矮星大多是单星。由于在数量上占主导地位，这甚至导致了一种说法，即银河系中所有燃烧氢的恒星中的大多数都是单身的。然而，近年来相当大的观测进展也揭示了，大约四分之一的恒星可能由更高级别的恒星系统组成；猎户座星座中的大质量恒星表明，这一比例据信要高得多。因此，等级倍数是恒星形成过程中的重要组成部分，而恒星质量在多大程度上与恒星质量有关也是一个关键问题。本文提出了用高分辨光谱方法研究质量在0.8-100M☉范围内恒星的多重数分数。南方的样本包括来自银河O星汇编的所有(~250)O星，以及260颗B星和170颗F/G星，所有这些都将通过多历元光谱进行观测。北方的样本由大约350颗附近的F型和G型恒星组成，这些恒星已经获得了高分辨率的光谱。除了O星外，所有天体都形成了无偏和体积完整的样本，这些样本取自依巴谷档案馆。从这些数据中，我们希望得到SB1和SB2系统作为恒星质量的函数的分数。我们打算确定恒星的光谱类型和/或基本恒星参数，并将这些数据与导出的恒星多重性、金属丰度和质量联系起来。

Although it is usually asserted that most stars form as binaries, more recent investigations on low-mass stars suggest that M-, L- and T-type dwarfs are mostly single. Being the dominant population by number, this has even led to the suggestion that the majority of all hydrogen-burning stars in the Milky Way Galaxy are single. However, the considerable observational progress in recent years has also brought to light that up to about one quarter of all stars may consist of higher level star systems; this fraction is believed to be even much higher as indicated by massive stars in the Orion Trapezium. Thus, hierarchical multiples appear to be an important part of general star formation and it is a key question to what extent the stellar mass is involved.It is proposed to investigate the multiplicity fraction for stars in the mass range of 0.8 - 100 M☉ based on about 1000 stars with high-resolution spectroscopy. The southern sample consists of all (~ 250) O stars from the compilation of Galactic O Stars as well as of 260 B and 170 F/G stars, all to be observed by multi-epoch spectroscopy. The northern sample comprises about 350 nearby F- and G-type stars where high-resolution spectra have already been taken. Apart from the O stars, all objects form unbiased and volume-complete samples taken from the Hipparcos archive.From the data we wish to obtain the fraction of the SB1 and SB2 systems as a function of stellar mass. We intend to determine the spectral types and/or the basic stellar parameters of the stars and shall relate these data in terms of the derived stellar multiplicities, metallicities and masses.