Eclipsing binary(English: eclipsing binaries), also known asEclipsing variable star、Luminosity binary、Light variable binary、Eclipsing binary, which means that the orbits around each other are almost parallel to the line of sight plane of the observer, and will eclipse each other, resulting in brightnessPeriodic changeOfKonductraSystem.
The eclipsing binary system consists of two sub stars, a brighter main star and a darker companion star, which move around the common mass center under the mutual attraction, and their orbits around each other are almost in the line of sight direction. The two stars will eclipse each other (one sub star passes in front of the other, just like the moon eclipses the sun), resulting in regular brightnessPeriodic changeThe double star system.[1]
Discovery History
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The first discovered eclipsing binary isFive Tombs(Perseus beta), which is 2.13 at its brightest (photoelectricVisual magnitude, the same below), the darkest time (called the main and minimum eclipse) is 3.40, which is caused by the partial eclipse of star A by star B.When B is partially eclipsed by A, the whole binary becomes 2.19 (called sub minimumFood gluttony）。The orbit period of Dalingwu is 2.8673075 days.It takes about 4.9 hours for its brightness to drop from normal to the darkest, and 4.9 hours for its brightness to return from the darkest to normal.
The Arabs discovered that the brightness of the star β Perseid (five mausoleums) has periodic changes for a long time. At that time, the astronomical theory believed that the brightness of the star would never change, so they used ghosts to explain the phenomenon of brightness changes and named it "Magic Star" (غووو), which means "ghoul".In May 1783, the 18 year old Dutch born British astronomer John GoodrickeRoyal SocietyThe cross eclipsing binary theory of the brightness variation of the Perseus beta star was published.After long-term observation, he found that the brightness of β - star Perseus began to brighten when it dropped to one third of the original brightness, and then began to darken after returning to the original brightness, and so on.He calculated that the brightness light change period of the Perseus beta star is 2 days 20 hours 49 minutes 09 seconds (the modern actual value is 2 days 20 hours 48 minutes 56.5 seconds), and proposed that the brightness light change is caused by the eclipse of the companion star with darker brightness in front of the parallel direction between the host star with higher brightness and the observer's line of sight plane.
classification
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The light curves of eclipsing binaries (see the attached figure) can be divided into three types:
① Five types of Daling, with little change outside the food;
②Gradual Stage II（Lyraβ) Type A, also significantly dimming outside the food, but the main part is very smallFood gluttonyIt is much darker than the next smallest food;
③Ursa Major WType A, the light outside the food is significantly dimmed, and the main mini food is slightly darker than the sub mini food.
By analyzing the light variation curve of eclipsing binaries, we can reliably obtain the radius of large stars, small stars (both in terms of the semi major axis of the orbit), the inclination angle of the orbital plane (the intersection angle of the normal line of the orbital plane and the line of sight), large stars or small starsluminosity(in total luminosity), reflecting the brightness distribution of large stars and small stars“Edge darkening coefficient”Etc., collectively referred to as photometric orbital solutionPhotometry solutionOr meteringOrbital elements。If this binary star is bispectrum againSpectroscopic binary(See the close binary), and there is a relatively reliable spectral orbital solution, then combined with the above photometric orbital solution, we can get the respective mass and radius of the two sub stars that make up the binary (in order toSolar massAnd solar radius).Therefore, some eclipsing binaries can provide reliablefixed starThe basic parameters become the basic parameters for the study of stellar physics andStellar evolutionOne of the important foundations of.However, because most eclipsing binaries always have "personalities" that deviate from the "ideal commonality", the number of eclipsing binaries that have measured the basic physical parameters is not only small, but also the data is not accurate enough.
Research History
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Published by the Soviet Union in 1969General List of Variable StarsMore than 4000 pairs of eclipsing binaries have been collected, but the《Photometric orbit solution table of eclipsing binary》Only 221 pairs of binary star data are selected, many of which need to be improved.Therefore, it is necessary to continuously improve the measurement technology and analysis theory to measure more accurate basic parameters of binary stars.Published semi annually in Sweden《Close binary literature and work records》AndInternational Astronomical UnionThe records of close binaries in the conference proceedings published every three years are the basic materials for the study of eclipsing binaries.Published annually in Poland《Eclipsing ephemeris》The 1980 eclipsing variable star calendar published in 1979 lists 856 pairs of binary starsFood gluttonyThe timetable is very useful for astronomers and amateur astronomers.
Research achievements
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The achievements in the study of eclipsing binaries are manifold:
① The physical parameters such as mass and radius of 100 pairs of close binaries have been obtained.
② YesColumn II（Aurigaζ) Type eclipsing binaryBlue dwarfLight passing throughRed supergiantObservations of various layers of the atmosphere show that many red supergiant starsChromosphereStructure and chromosphere activity data.
③ According toElliptical orbitThe near star point movement of eclipsing binary stars is introducedfixed starInternal density distribution characteristics.
④ According to the nova that is also an eclipsing binary (such as 1934HerculesNova), through multiple studies on X-ray eclipsing binaries (such as X-1 in Hercules)Pulsating variable starThe eclipsing binary of (e.g., Aries RW) and containsDazzling starsThe eclipsing binary of (e.gBeihe IIWe have learned a series of physical properties about nova, X-ray stars, pulsating variable stars and flare stars.
⑤ We have studied whether the relevant X-ray stars areneutron starProblems.
⑥ We can measure the eclipsing binary stars such asCepheusVW、X-ray of Cygnus V729;In 1979, the discovery of radio eclipsed eclipsing binary stars such asScorpioAR，These two discoveries have opened up a new field for the study of eclipsing binaries.
⑦ YesStar AssociationAndclusterThe study of eclipsing binaries in, and related to the star association where the eclipsing binaries are located, the age of star clusters, chemical composition, etcfixed starThe research of group provides effective clues.
⑧ Among all kinds of binary stars, eclipsing binary stars are the farthest type of binary stars that can be measured at present. The discovery of eclipsing binary stars in other galaxies has opened up a unique way for the study of galaxies.
Existing problems
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But there are still many problems in the study of eclipsing binaries.Having studied for more than 300 yearsFive TombsAlthough we got bispectrum in 1978Spectroscopic binaryThe spectral orbital solution significantly improves itsPhysical parametersReliability, but itsRadio burstandX-rayBoth the measured work and theoretical explanation of are not enough.The discovery of a dimming eclipsing binary in 1784Gradual Stage IIIt is still a mystery what kind of object the darker star is after years of high dispersion spectral analysis and satellite observation.Many short cycle (less than 1 day)“Connected binaries”OfQuality communicationThe dynamics and physics of energy exchange are not clear.Globular clusterWhether there are physical binaries in member stars is also an important problem to be solved in the evolution.To this end, astronomers from the Federal Republic of Germany and other countries have been looking for eclipsing binary stars in globular clusters.The study of eclipsing binaries in radio band has just begun,Gamma rayThe eclipsing binary in the S band has yet to be discovered.
