Binary Stars

Spectroscopic Binary Stars

光谱双星

A surprisingly large fraction of the stars are in binary or multiple star systems. Sometimes the binary stars are obviously separated, like 61-Cygni in the close neighborhood of the Sun. They are called "visual binaries". Others can be detected from periodic variations in luminosity associated with the eclipsing of one star by the other. Still other can be detected from the overlapping of different kinds of spectra. Modern interferometric measurements have added to our ability to distinguish and study binary stars.

令人惊讶的是，大量恒星都是双星或多重星系统的一部分。有时，双星系统显然可以被分辨，例如天琴座61，它位于太阳的近邻。这类系统被称为“视双星”。其他双星则可以通过一个恒星被另一个恒星遮挡所引起的周期性光度变化来检测。还有些双星则可以通过不同光谱的重叠来检测。现代干涉测量技术的引入，增强了我们分辨和研究双星系统的能力。

This image adapted from the Australia Telescope National Facility, see Ref.

这张图像改编自澳大利亚望远镜国家设施，参见参考文献

Binary stars can be detected from the red shift of the spectrum of one star while the other is blue-shifted.

双星系统可以通过其中一颗星的光谱红移而检测到，另一颗星则呈现蓝移。

Binary orbits can contribute to the measurement of the masses of different kinds of stars that appear in such systems.

二体轨道可以用于测量不同类型的恒星质量。

Eclipsing Binary Stars

食双星

A surprisingly large fraction of the stars are in binary or multiple star systems. Sometimes the binary stars are obviously separated, like 61-Cygni in the close neighborhood of the Sun. Others can be detected from periodic variations in luminosity associated with the eclipsing of one star by the other. Still other can be detected from the overlapping of different kinds of spectra. Modern interferometric measurements have added to our ability to distinguish and study binary stars.

令人惊讶的是，大量恒星都是双星或多星系统的一部分。有时，双星系统显然可以被分辨，例如天琴座61就位于太阳附近的近邻。其他双星系统则可以通过两颗恒星相互遮蔽所引起的周期性光变来探测。还有些双星系统则可以通过不同光谱的重叠来探测。现代干涉测量技术的出现，增强了我们分辨和研究双星系统的能力。

This image accessed from the Australia Telescope National Facility, see Ref. Image credit ESA

这张图像来自澳大利亚望远镜国家设施，参见参考文献。图注：欧洲航天局

The light curve of the eclipsing binary star system HIP59683 shows the change in apparent magnitude.

食双星系统HIP59683的光变曲线显示了视星等的变化。

Note that the apparent brightness is greater for a lower value of the apparent magnitude so the dips in the curve represent lower brightness. The Primary Eclipse shown gives a magnitude change of about 0.7 , which is about 1/2 the intensity. The primary eclipse represents the eclipsing of the hotter star by the cooler star (see Ref for simulation of light curves).

Binary orbits can contribute to the measurement of the masses of different kinds of stars that appear in such systems.

二体轨道可以用于测量不同类型的恒星质量。

注意， apparent magnitude 值越低， apparent brightness 越大，因此曲线中的 dips 表示较低的 brightness。主食变星所示的光变曲线显示 magnitude 变化约为 0.7，这大约是 intensity 的一半。主食表示较热的星被较冷的星遮蔽（见参考文献以模拟光变曲线）。