多普勒效应如何把光谱线位移翻译成恒星的视向速度？
How does the Doppler effect translate spectral-line shifts into a star's radial velocity?
恒星沿视线运动会使吸收或发射谱线整体移动：靠近则蓝移（波长变短）、远离则红移。由波长偏移量除以静止波长等于视向速度除以光速，可解出视向速度。高精度（米/秒级）视向速度法是探测系外行星与双星的关键手段。
Line-of-sight motion shifts spectral lines: approaching yields blueshift (shorter wavelength), receding redshift. From Δλ/λ0 = v_r/c one solves the radial velocity v_r. High-precision (m/s) radial velocities are key to detecting exoplanets and binaries.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Terence Dickinson,《NightWatch》第4版,Firefly Books,2006
T. Dickinson, NightWatch: A Practical Guide to Viewing the Universe, 4th ed., Firefly Books, 2006; Chinese ed.
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL19287031W：Nightwatch : a practic
#多普勒效应 #视向速度 #系外行星
造父变星的周光关系为什么能充当宇宙距离阶梯的标尺？
Why can the Cepheid period–luminosity relation serve as a rung of the cosmic distance ladder?
造父变星脉动周期与其本征光度严格正相关（Leavitt 定律）。测得周期即可知绝对星等，再与视星等比较得到距离，误差可控制在约 5% 内。它是本地宇宙到邻近星系距离测量的关键一级阶梯。
A Cepheid's pulsation period correlates tightly with its intrinsic luminosity (Leavitt's law). Measuring the period gives absolute magnitude; comparing with apparent magnitude yields distance to ~5% precision. It is a key local rung of the distance ladder out to nearby galaxies.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Zeilik,《Astronomy: The Evolving Universe》第9版,Cambridge University Press,2002
M. Zeilik, Astronomy: The Evolving Universe, 9th ed., Cambridge University Press, 2002
#造父变星 #周光关系 #距离阶梯
金属丰度 [Fe/H] 在恒星天文学中如何定义和表示？
How is metallicity [Fe/H] defined and expressed in stellar astronomy?
[Fe/H] 等于恒星的铁氢对数丰度减去太阳的铁氢对数丰度，是以太阳为基准的相对值。负值表示比太阳更贫金属。它用于刻画恒星年龄、星系化学演化与星族差异。
[Fe/H] is the iron-to-hydrogen abundance of a star minus that of the Sun on a log scale; negative values mean more metal-poor. It traces stellar age, galactic chemical evolution, and population differences.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Zeilik,《Astronomy: The Evolving Universe》第9版,Cambridge University Press,2002
M. Zeilik, Astronomy: The Evolving Universe, 9th ed., Cambridge University Press, 2002
#金属丰度 #化学演化 #星族
视星等与绝对星等的区别是什么，如何互相换算？
What is the difference between apparent and absolute magnitude, and how are they converted?
视星等描述地球上看到的亮度，绝对星等是天体置于 10 秒差距标准距离时的亮度，反映本征光度。两者通过距离模数（视星等减去绝对星等等于 5 倍对数距离比）联系，距离越远视星等越大（越暗）。
Apparent magnitude is the observed brightness from Earth; absolute magnitude is the brightness at a standard 10 pc distance, reflecting intrinsic luminosity. They connect via the distance modulus m−M=5 log10(d/10 pc); farther objects appear fainter.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Zeilik,《Astronomy: The Evolving Universe》第9版,Cambridge University Press,2002
M. Zeilik, Astronomy: The Evolving Universe, 9th ed., Cambridge University Press, 2002
#视星等 #绝对星等 #距离模数
滤光系统（如 Johnson–Cousins UBVRI）在测光中起什么作用？
What role do filter systems like Johnson–Cousins UBVRI play in photometry?
不同滤光片只透过特定波段的光，测得的星等组合（色指数如 B−V）反映恒星温度与红化。标准滤光系统使全球望远镜的测光可相互校准与比较，是恒星测光与变星监测的基础。
Different filters pass only specific wavelength bands; magnitude combinations (color indices like B−V) reveal temperature and reddening. Standard filter systems let photometry from telescopes worldwide be calibrated and compared—the basis of stellar photometry and variable-star monitoring.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Bessell,《UBVRI passbands》,Publications of the Astronomical Society of the Pacific,1990 (DOI: 10.1086/132749)
Bessell, 'UBVRI passbands', Publications of the Astronomical Society of the Pacific, 1990, DOI: 10.1086/132749
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1086/132749
#滤光系统 #色指数 #测光
盖亚（Gaia）卫星怎样通过天体测量建立三维星图？
How does the Gaia satellite build a 3D star map through astrometry?
盖亚以极高精度测量十亿余颗恒星的天球位置、自行与视差，视差直接给出距离，自行揭示横向运动，再结合测光得到温度与光度。其数据革命性地绘制了银河系的三维结构与运动学。
Gaia measures positions, proper motions, and parallaxes for over a billion stars with extreme precision; parallax gives distance directly, proper motion reveals transverse motion, and photometry yields temperature and luminosity—revolutionizing the 3D map and kinematics of the Milky Way.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
van Leeuwen,Astrophysics and Space Science 333:29 (2007);Gaia 合作组,Astronomy and Astrophysics 649:A1 (2021)
van Leeuwen, Astrophysics and Space Science 333, 29 (2007); Gaia Collaboration, Astronomy and Astrophysics 649, A1 (2021)
#盖亚 #视差 #自行 #天体测量
恒星光谱型 OBAFGKM 的排序依据是什么？
What is the basis for ordering stellar spectral types OBAFGKM?
这一序列按恒星表面温度从高到低排列（O 最热、蓝，M 最冷、红），由吸收线特征决定：O 型以电离氦线为主，F/G 型见氢与金属的精细线，M 型则由分子带（如氧化钛）主导。它是哈佛分类法的核心。
The sequence orders stars by decreasing surface temperature (O hottest/blue to M coolest/red), diagnosed by absorption-line features: O shows ionized helium, F/G show hydrogen and metal lines, and M is dominated by molecular bands (e.g., TiO). It is the core of the Harvard classification.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Gray《恒星光球的观测与分析》（Cambridge University Press）
Gray, The Observation and Analysis of Stellar Photospheres (Cambridge University Press)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787895490765（豆瓣书目条目: 恒星光球的观测与分析）
#光谱型 #表面温度 #哈佛分类