synonymStellar system(Celestial system) generally refers to star system
permanentGalaxyUnification is an astronomical term.Star system or stellar system refers to a system in which a few stars are bound by gravity and encircle each other. A large number of stars are bound by gravity and are generally called star clusters or galaxies, but generally speaking, they can be called stellar systems.Stellar systems are sometimes used alone but with smallerPlanetary systemSurrounding stars.
The stellar system is composed of stars and planets around itsphere systems 。
The formation and operation of the system have certainRegularityAnd periodicity.
As the stellar system evolves, its internal stars may becomeWhite dwarf，neutron starOr black holes.Nova may occur in the star system with white dwarfs.The system composed of multiple black holes may also exist stably for a period of time.
Intersatellite system
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The stellar system composed of two stars is called conjoined starIntersatellite system, binary star systemPhysical binary star or binary star system。
If there is no tidal effect, perturbation or mass transfer between stars in the conjoint star system, it will exist stably.In a stable intergalactic system, the stars willcentroidFocusedElliptical orbitRun on.(i.eTwo body problem）
The known conjoint star systems areSirius, Nanhe SanheCygnus X-1。The system where Cygnus X-1 is located may be composed of black holes.
Aggregate system
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Gathering star system (physicsAggregate star）It is a system composed of three or more stars.
The aggregate system can be classified and named according to the number of stars inside:
Three stars constitute a three body system,TriadSystem, triple star or triple star system;
The system of four stars is calledQuadrangleSystem;
The system composed of five stars is called pentagram system;
The system of six stars is calledHexagramSystemand so on.
The largest accumulation star system discovered is the seven star system.
But these systems are far smaller than some with hundreds or thousands of stars,Dynamic systemMore complexOpen cluster。
The aggregate system is more complex than the simulation of the conjunction system.WhenMultibody problemOfdynamic systemDuring interventionChaosBehavior.Many hot star systems are unstable.For example, if two stars are too close, the smaller one will speed up to pass by the other and escape from the system.This situation can be compared with the "three stars" in Three Bodies.
Many known star systems are triads;As the number of stars increases, the number of constellations decreases exponentially.Of the 728 poly star systems listed in the revised Tokovin catalog in 1999, 551 are trinity star systems.But becauseSelection effectThe statistics on these knowledge are often incomplete.
Step model
However, if the system is operated by a hierarchical model, it may be stable.In the hierarchical model system, several stars areSubsystemRunning, several subsystems as a whole around a larger trackcentroidwork;The subsystem may also be subdivided into smaller subsystems, and sometimes it may even continue to be subdivided.
In this case, each star will continue to move around the center of mass of the system in a more stable Kepler orbit.Unlike those with a large number of starsGalaxyAnd star clusters.
Triple star systems are usually hierarchical models: these systems can generally be divided into a pair of conjoined stars and a distant starcompanion。Neighboring galaxyIs a typical example (different from that in the novelThree body problemModel).
Aggregation systems with more stars are also hierarchical models.
This system is the prototype of Three Bodies, which can be referred to in the previous section.The conjoined satellite system is composed ofAlpha Centauri The companion star is well-knownAdjacent star。The nearest neighbor star is 4.2 light-years away from the sun, while the associated star system is 4.6 light-years away from the sun.
Gliese667
This system also belongs to the typical 2+1 model.The companion star 667C has several satellites, and the third planet 667Cc is possibleHabitable planet。
This system is reversed, and the companion star has greater mass, and the associated star system revolves around this companion star.It is known that it takes 158 days for two stars inside the conjoint star system to go around once, and it takes 25.7 years to go around the companion star.
This system can be divided into three linked star systems, namely 2+2+2.One pair of linked star systems runs around each other in a similar way, and the other runs around two systems at a relatively long distance, namely (2+2)+2.
ADS 9731
This system can be divided into two triple star systems, namely 3+3.Two of themStructure of the systemSimilarly, a companion star surrounds a conjoint star system, namely（2+1)+(2+1)。
According to foreign media reports, according to the definition of modern science, the so-called stellar system usually refers to the celestial structure with one star and one to dozens of planets of various types running around it.All star systems follow one of the most important conditions: the center is a huge and hot star.Of course, individual star systemsChina CouncilIt has two stars, the so-calledDouble star system。However, from now on, the above point of view will have to be modified - Spitzer infraredSpace telescopeA star system composed of four "suns" has been discovered for the first time.At first, Spitzer telescope observed an unusually large gaseous dust disk revolving around the binary star system.In general, such disc structures are stored for breeding planetsasteroidAnd other celestial bodies.However, the subsequent observation shocked scientists: there were two stars in the disk structure, and their gravity also had a significant impact on the operation of the disk.
NASA astronomers said that the disk structure discovered by Spitzer telescope consists of two rings.This means that two planetary belts will be distributed in this star system with four "suns" in the future.If there is life on a planet in the solar system, they will see four "suns" at the same time.It is reported that the number of this unique star system isHD 98800B，It is about 10 million light years away from the earth.At the same time, the system appears very "lonely" - the nearest constellation, Serpent, is 150 light-years away.
NASAIt is pointed out that although the four stars in HD 98800B system have gravitational effects, the distance between each pair of stars is very large, close to 50Astronomical unit(One astronomical unit is equivalent to the average distance between the earth and the sun, about 150 million kilometers), andPlutoThe distance to the sun is equal.Further observation of this strange system shows that in the two rings forming the disk, one is about 5.9 astronomical units away from the two stars in the center, and the other is about 1.2 astronomical units away.However, planets may not evolve in the near ring structure, which is most likely to become the cradle of asteroids and comets.In another ring structure, it is very likely to breed planets.
University Of California Ellis Felland, an astrobiologist ofPlanetary diskThe formation of free passage means the formation of planets.But there are two relatively independent primitive planetary disks in HD 98800B system, and they are also affected by the gravity of four stars. "
The calculation results show that the first batch of HD 98800B will be born in millions of yearsPlanetary systemSystem.
