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Glossary term: 变星

Redirected from 激变变星

Description: 变星是指对观测者而言亮度随时间发生明显变化的恒星。实际上,由于恒星的演化,所有恒星的亮度都会在数百万年或数十亿年内发生变化。而变星一词通常是指那些发生亮度变化的时间尺度远远短于其演化时标的恒星。

产生光变有几种可能的物理机制。有些恒星,如仙王座变星或天琴座RR型变星,它们是不稳定的,且会发生脉动,使得其大小和亮度发生变化。

其他恒星会喷射出明亮的物质,从而增加观测到的总体亮度("爆发变星")。有一类被称为灾变变星或新星的恒星,它们的亮度会突然增加,然后又恢复到以前的水平。这类系统通常由一对恒星组成,其中一颗恒星的物质流向另一颗恒星,一旦达到某个临界点,就会发生核聚变反应。其中一个伴星或另一个伴星发生大爆炸并变亮。

还有一些恒星看起来变化是因为它们在旋转,交替地向我们展示亮度较高和亮度较低的一面,或者是由于双星系统绕着彼此运行,其中一颗恒星周期性地被另一颗遮挡。后一类双星被称为食双星。

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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

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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Related Diagrams


猎户座呈沙漏状,两串恒星分别向东北和西北方延伸

猎户座星图

Caption: 猎户座及其明亮的恒星和周围的星座。猎户座被金牛座、波江座、天兔座、麒麟座和双子座环绕(从上往下顺时针依次排列)。猎户座最亮的恒星参宿四和参宿七分别位于星座的北端(图中上部)和南端(图中下部),中间是著名的三星 "腰带"。 猎户座横跨天赤道,因此在一年中的某些时候,从地球上的任何地方都能看到它。在世界上最北极或最南极地区,可能看不到猎户座的某些部分。猎户座在北半球冬季和南半球夏季的晚上最为明显。猎户座上方的蓝线标志着黄道,即太阳在一年中划过天空的轨迹。太阳从不经过猎户座,但人们偶尔会在猎户座发现太阳系的其他行星和月球。 在猎户座腰带的正南方,有两个梅西叶天体M42(猎户座星云)和M43,用绿色方框标出。这些星云和M78(腰带左边的绿色方框)是巨大的猎户座分子云团的一部分。它覆盖了猎户座的大部分区域,包括这些分子云正在坍缩形成新星的区域。 该图的 y 轴表示赤纬,单位为度数,以北为上,x 轴表示赤经,单位为小时,以东为左。这里标注的恒星大小与恒星的视星等有关,视星等是衡量恒星视亮度的标准。较大的点代表较亮的恒星。希腊字母表示星座中的亮星。这些恒星按亮度排序,最亮的恒星被标记为α星,第二亮的为β星,等等,不过并不总是完全遵循这种排序。围绕着参宿四的圆圈表示它是一颗变星。虚线是国际天文学联合会划定的星座边界,绿色实线是表示星座的常用形式之一。星座边界和连接恒星的线条都不会出现在实际天空中。
Credit: 由国际天文学联合会天文教育办公室根据国际天文学联合会/《天空与望远镜》的原文改编

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons


天蝎座看起来像相连的T字形和J字形。黄道从东经向西偏西方向运行,夹住了T字形的一臂。

天蝎座星图

Caption: 天蝎座及其明亮恒星与周边星座示意图。从顶部开始沿顺时针方向,天秤座周边的星座依次为:蛇夫座、巨蛇头、天秤座、豺狼座、矩尺座、天坛座、南冕座和人马座。天蝎座最亮的恒星是心宿二,位于天蝎座的中心,其东南方(左下方)是著名的天蝎尾。天蝎座位于黄道上。从地球看来,太阳以一年为周期在天球上移动,所经过的路径称为黄道,在图中以蓝色实线标注。太阳只在每年十一月下旬的很短一段时间内位于天蝎座。太阳系中的其他行星也经常出现在天蝎座。 天蝎座位于天赤道以南。北极地区无法看到整个天蝎座,亚洲、欧洲和北美洲北部地区的观测者也无法看到天蝎座的部分区域。天蝎座在北半球的夏季和南半球的冬季夜晚最适宜观测。 疏散星团M6、M7和NGC 6231在图中均以黄色圆圈标注,球状星团M4和M80在图中均以叠加了十字符号的黄色圆圈标注。 该图的纵轴为赤纬,横轴为赤经,方向为上北下南左东右西。图中标注的恒星大小对应其视星等——衡量天体视亮度的标准,较大的圆点代表着较亮的恒星。图中的希腊字母标注着星座中最亮的恒星。这些恒星按亮度排序,最亮的一般被标记为α星,第二亮的一般为β星,等等,不过这种字母排序并不总是和实际亮度排序完全一致。图中虚线标注的是国际天文学联合会划定的星座边界,绿色实线则是一种常见的星座形象连线。需要注意的是,在实际观测时,这些边界与连线都不会出现在天空中。
Credit: 国际天文学联合会天文教育办公室(IAU OAE)根据国际天文学联合会和《天空与望远镜》的原文改编

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons


Cetus appears as two ellipses, the smaller one north-east of the larger one, connected by a line.

Cetus Constellation Map

Caption: The constellation Cetus along with its bright stars and surrounding constellations. Cetus is surrounded by (going clockwise from the top): Pisces, Aquarius, Sculptor, Fornax, Eridanus, Taurus and Aries. Cetus lies just south of the ecliptic (shown here as a blue line), this is the path the Sun appears to take across the sky over the course of a year. While the Sun does not pass through Cetus, the other planets of the solar system and the Moon can sometimes be found in Cetus. The star Omicron Ceti or Mira is a famous variable star. This red giant varies in brightness by a factor of 600 over the course of its eleven month period. Cetus spans the celestial equator, thus some part of the constellation is visible from all the the Earth at some point in the year. The full constellation is visible from equatorial and temperate regions of both hemispheres. Cetus is most visible in the evenings in the northern hemisphere late autumn and the southern hemisphere late spring. The barred spiral galaxy M77 lies in Cetus as does the spiral galaxy NGC 247 and the dwarf irregular galaxy IC 1613. All three are marked here with red ellipses. The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. Mira is marked with an open circle as it is a variable star not always visible to the naked eye. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the line marking the ecliptic, nor the lines joining the stars appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by IAU/Sky & Telescope

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons


Carina appears as the hull of a line drawing of a ship which faces left (east). Canopus is on its right (west) edge

Carina Constellation Map

Caption: The constellation Carina along with its bright stars and surrounding constellations. Carina is surrounded by (going clockwise from the top): Vela, Puppis, Pictor, Volans, Chamaeleon, Musca and Centaurus. Carina is notable for Canopus, the second brightest star in the night sky and for the famous variable star Eta Carinae. This latter object is a binary star system of two young very massive stars. Its brightness has varied greatly over the past few centuries. At one point it outshone Canopus before dimming by a factor of four thousand to become invisible to the naked eye. In recent years it has brightened enough to again be visible without the aid of a telescope. Carina is a southern constellation and thus the whole constellation is visible at some point in the year to the entire southern hemisphere. The whole constellation is also visible from equatorial regions of the northern hemisphere with parts of the constellation visible from northern temperate regions. The open clusters NGC 2516, NGC 3532 and IC 2602 lie in Carina. These are marked here by yellow circles. The Carina Nebula, also known as NGC 3372, lies in the constellation. This large nebula contains many massive young stars, including Eta Carinae. This diagram maps an area around the south celestial pole. Here lines of constant right ascension converge. The right ascension values of these lines are marked on the x-axis above and below the diagram. Some of the lines of constant declination are marked on the y-axis. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. Carina was previously part of the larger Argo Navis constellation along with Vela and Puppis. As the letter designations for stars were created before this division took place, Greek letter designations are now divided between the three constellations with Carina having stars designated alpha and beta but no gamma or delta. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the lines joining the stars appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons


Perseus resembles a crudely-drawn person with a round body and head tilting to the north west

Perseus Constellation Map

Caption: The constellation Perseus with its bright stars and surrounding constellations. Perseus is surrounded by (going clockwise from the top): Camelopardalis, Cassiopeia, Andromeda, Triangulum, Aries, Taurus and Auriga. Perseus is home to the notable variable star Algol. Perseus is a northern constellation and thus the whole constellation is visible at some point in the year throughout the northern hemisphere. The whole constellation is also visible to equatorial regions of the southern hemisphere with parts of the constellation visible to southern temperate regions. Perseus is best viewed in the evenings in the northern hemisphere winter and southern hemisphere summer. The open clusters NGC 869 and NGC 884 (commonly known as the Double Cluster) lie in Perseus as does the open cluster M34. These are all marked with yellow circles. The brightest star in Perseus, Mirfak (alpha Persei), along with some of the surrounding stars are members of the Alpha Persei open cluster. The planetary nebula M76 also lies in Perseus, it is marked here with a green circle superimposed on a plus sign. The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dot marking Algol is surrounded by a circle, showing it is a variable star. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. The blue line at the bottom left of the diagram marks the ecliptic. Neither the constellation boundaries, nor the lines joining the stars, nor the ecliptic, appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons