Description: 當天文學家觀測一個遙遠的天體時，視向速度是天體沿觀測者視線方向的運動分量 - 天體直接遠離或直接朝向觀測者運動。視向速度是利用多普勒效應測量的：對於向著我們移動的天體，光譜線會向較短的波長移動（藍移）；對於遠離我們的天體，光譜線會向較長的波長移動（紅移）。視向速度總是相對於觀測者而言的。高精度測量通常採用相對於太陽系質量中心（"質心"）的參考系來給出視向運動速度，以扣除地球繞太陽運動的影響。相互繞行的天體的視向速度隨時間變化。當我們的視線方向恰好與軌道平面平行時，這種現象最為顯著。在這種情況下，軌道運動會週期性地使每個天體輪流遠離和靠近我們。即使天體本身無法被單獨看到，也可以利用視向速度測量來推斷這種軌道運動。由於質量越大，速度越快，這種測量可以用來估算軌道上天體的質量。這已被用於發現雙星或環繞恆星運行的系外行星，以及重構星團和整個星系的質量。宇宙膨脹就是通過對星系距離和視向速度的系統分析發現的。

Related Terms:

• 多普勒效應
• 光譜

Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher
The translation of this term and its definition is still awaiting approval

This is an automated transliteration of the simplified Chinese translation of this term

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