Supergiant: star name, located atHerotuThey are one of the brightest stars.TheirAbsolute magnitudeBrighter than - 2, etc.The brightest blue (hot) supergiant seen by the naked eye isRigelandTianjin IV, the brightest red (cold) supergiant isBetelgeuseandAntares 。
Chinese name
Supergiant
Foreign name
Supergiant star
Classification
fixed star
Quality
5 times solar mass to 100 times solar mass
Diameter
20 times the diameter of the sun to 1000 (or more) times the diameter of the sun
Supergiant stars are the most massive starsHerotuOccupies the top of the figure on theYork spectral classificationMedium belongs to Ia (very bright supergiant) or Ib (not very bright supergiant), but the brightest supergiant is sometimes classified as 0.The mass of supergiant stars is 5 to 150 times that of the sun, and the brightness is 2000 to millions of times that of the sun. Their radii also vary greatly, usually 20 to 500 times that of the sun, or even more than 1000 times that of the sun.Stefan Boltzmann law displayRed supergiantThe radiation energy per unit area is lower on the surface of the blue supergiant, so the temperature is cooler than that of the blue supergiant, so the red supergiant with the same brightness will be larger than the blue supergiant.Because their mass is so huge, they only have a short life of 10 to 50 million years, so they only exist in young cosmic structures, such as open star clusters, spiral galaxy spiral arms, and irregular galaxies.They are rare in the core sphere of spiral galaxies, nor in elliptical galaxies orGlobular clusterIt is observed in, because these objects are composed of old stars.
The spectrum of a supergiant occupies all types, from the O type spectrum of the early type of a blue supergiant to the M type spectrum of the late type of a red supergiant.Rigel, the brightest star in Orion, is a blue and white supergiant, while Betelgeuse and Antares in Scorpio are red supergiants.The modeling of supergiant models is still an active and difficult area in the research field, for example, the problem of star mass loss remains to be solved.New trends and research methods are not only to model a star, but also to model the entire star cluster, and to compare the distribution and changes of supergiant stars in it, such as the distribution state in the galaxy Magellanic Cloud.
The first star in the universe is believed to be brighter and larger than the stars in the universe.These stars are considered to be the third generation, and their existence is necessary to explain the spectral lines of only hydrogen and helium in the observation of quasars.The predecessor of most type II supernovae is considered to be a red supergiant. However,Supernova 1987AIts predecessor is a blue superstar.However, he may be a red supergiant before the strong stellar wind blows away several layers of gas shells outside.The largest stars known are sorted according to their volume as follows:Shield base UY、Cygnus NML、RW Cephei 、WOH G64、Cassiopeia PZ、Westelu 1-26、Sagittarius VX、Canis Major VY（the Garnet Star）。The above ranking is independent of brightness and weight.
The brightness of a supergiant is very large, indicating that its surface area is obviously larger than that of a non supergiant with the same spectral type.for exampleRed Superstar Shield UYIts radius is about 1708 ± 192 times of the sun's radius, the absolute magnitude is below - 7, about 50000 times brighter than the sun, and the total radiation energy is up to 340000 times of the sun.andBlue supergiantThe absolute magnitude of Tianjin IV is -8.37, about 230000 times brighter than the sun.Some blue supergiants have been detected,Huang Super GiantAnd the radio radiation of the red supergiant, which is important for the study of its atmospheric structure and activity,Peristellar matter, Xingfenghemass loss And other issues are very important.
High-energy observatorySatellite 2 has measuredOrionε. κ isostellarX-ray, this and theircoronae 、Stellar windAnd so on.Supergiants are obviously concentrated inGalactic surfaceandSwivel armNearby.Their dynamic characteristics andGalaxyThe gaseous substances in are similar.60% of superstars belong to O, BStar AssociationOr the Milky Waycluster。The age and evolution of supergiant stars are very important research topics, and there are many controversies.
radius
Supergiant stars are huge stars relative to the sun, but there are also significant differences in the radii of supergiant stars.The hottest and brightestType O supergiantOn the contrary, they are the smallest. They are generally 15 to 30 times larger than the sun.The coldest M-type red supergiant is usually more than 500 times of the sun, such asShield base UYThe diameter of this red supergiant is 1708 times that of the sun[1]。
Mass and luminosity
Traditional supergiant stars are all massive stars, and they have at least 5 times the mass of the sun.Some O - type supergiant stars can have more than 30 times the mass of the sun.For example, Betelgeuse in Orion has at least 40 times the mass of the sun.Because of its huge mass, supergiant stars are also very bright. Even the darkest yellow supergiant has more than 1000 times the thermal luminosity of the sun.Type O supergiant is the hottest and brightest supergiant, and the luminosity of a massive type O supergiant can exceed that of the sun by a million times.
Photometric changes of supergiant stars
Supergiants are unstable stars, and most of them are light variable.
Quite a few of the blue supergiants belong toAlpha Cygni variables And most of the Lante supergiant stars belong to LBV bright blue variable stars (also known as high luminosity blue variable stars)
There are numerousCepheid variable, and SRdSemiregular variable star。Among them, SRd type variable stars include the brightest yellow supergiant and super giant, which are giants of stars.
Almost all red supergiants are variable stars, and they generally belong to SRc and Lc types. The former has multiple periods, and the latter is explosive dimming without fixed dimming periods.
classification
Announce
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Supergiants are divided into blue supergiant (type O to type A), yellow supergiant (type F to type K early), and red supergiant (type K late to type M)
The temperature range of a supergiant is very wide. The hottest blue supergiant, such as WR25 in the Carina nebula, has a surface temperature of nearly 50000K, and the coldestM-type supergiantMost of them are located near 3500K.The coldest known supergiant isSagittarius VXThe average surface temperature of the star is only 2900K.
Supergiants can be classified into Ia (bright supergiant, such as Tianjin IV), Iab (medium brightness supergiant, such asTianjin I）, Ib (weaker supergiant, such asEndangered Sleeping Three）。In addition, there are some stars between super giant stars and bright giant stars, forming a transition zone (most of these stars have shorter periodsClassical Cepheid Variable, for examplePolaris、Cepheid I）。
In addition to the traditional young and massive typical super giant stars, some small and medium-sized stars will also have some super giant properties at the end of their evolution, so the spectral classification of super giant stars is obtained.But in essence, they are totally different from the typical supergiant stars.for exampleTaurus RV type variableThey are often classified as bright yellow to orange supergiants, but in fact their brightness is much smaller than that of Ia type (F8Ia typeWezen It has more than 80000 times the brightness of the sun, while most of the Taurus RV type variable stars are not more than 10000 times the brightness of the sun), and its mass is only 60% of the sun.These stars only have supergiant like spectra due to the extreme low surface gravity at the end of their evolution.In fact, they used to be ordinary stars similar to the sun.
Other similar pseudo supergiants include Virgo W-type variable stars, some of which are extremely expansiveLong-period variable star，Telescope pedestalPV type variable stars andR-type variable star of northern corona。Their common feature is that they are of low quality, with ages up to billions or even tens of billions of years. They are late stars that are about to evolve into white dwarfs[2]。
dwarf star
Dwarf star: A small main sequence star like the sun. If it is a white dwarf star, it is the remains of a star like the sun.Brown dwarfThere is not enough material for melting reaction.Originally refers to a star with weak luminosity, now specifically refers toStellar spectral classificationThe star with luminosity level V in is equal toMain sequence star。Dwarfs with spectral types O, B and A are calledBlue dwarf(such as Weaver 1 and Sirius). The dwarf stars with spectral types F and G are calledYellow dwarf(such as the sun), dwarf stars with spectral type K and later are calledRed dwarf(e.gAlpha B star).But white dwarfsSub dwarf、“Black dwarf”It is not a dwarf star.A class of stars with weak luminosity whose matter is in the degenerate state“Degenerate dwarf”It is also not a dwarf star.
“Black dwarf”It is theoretically estimated that there is an object, which is finally evolved from a star whose mass is roughly the mass of a sun or smaller, and it is in a cold degenerate state and no longer emits radiant energy;Others specifically refer to those with insufficient mass (less than about 0.08 solar mass) and no nuclear reaction energyAstral body。
SuperStar
In astronomy, it refers to a star whose luminosity is larger than that of an ordinary star (main sequence star) and smaller than that of a supergiant starfixed star。
Supergiant is the star with the largest mass, occupying the top of the Herro diagram. It belongs to Ia (very bright supergiant) or Ib (not very bright supergiant) in the York spectral classification, but the brightest supergiant is sometimes classified as Ia0.The mass of a supergiant is 8 to 30 times that of the sun, and its brightness is 10000 to millions of times that of the sun. Its radius also varies greatly, usually 20 to 500 times that of the sun, or even more than 1000 times that of the sun.
Stefan Boltzmann's law shows that the surface of a red supergiant has a low radiant energy per unit area, so the temperature is relatively cold relative to a blue supergiant. Therefore, a red supergiant with the same brightness will be larger than a blue supergiant.Because their mass is so huge, their life span is only 10 million to 50 million years, so they only exist in youngCosmic structureMedium, likeOpen cluster、spiral galaxyThe vortex arm of, andIrregular galaxy。
It is rare in the nuclear sphere of spiral galaxies, and has never beenElliptical galaxyOr globular clusters, because these objects are composed of old stars.The spectrum of a supergiant occupies all types, from the O type spectrum of the early type of a blue supergiant to the M type spectrum of the late type of a red supergiant.Rigel, inOrionThe brightest star in the sky is a blue and white supergiant, while Betelgeuse and Antares in the constellation Scorpius are red supergiants.
The modeling of supergiant models is still an active and difficult area in the research field, for example, the problem of star mass loss remains to be solved.New trends and research methods are not just to shape the model of a star, but to shape the wholeclusterAnd to compare thedistributionAndchange, for example, in galaxiesMagellanic Clouds Distribution status in.The first star in the universe is believed to be brighter and larger than the stars in today's universe.These stars are considered to be the third generation, and their existence is explained bya quasarIn our observation, only the spectral lines of hydrogen and helium are necessary.
Most of the second typeSupernovaThe predecessor of supernova 1987A is considered to be a red supergiant, while the predecessor of supernova 1987A is a blue supergiant.However, it is possible thatStellar windHe was a red supergiant before blowing away the outer layers of gas crust.Then look for<pre>, of course, the density of neutron star is large, and the formula is ρ (density)=M (mass)/V (volume).The density of neutron star is 1 billion tons/cubic centimeter,White dwarf1 million tons/cubic centimeter, supergiant less than 1 g/cubic centimeter, metallic osmium 22 g/cubic centimeter[3]。
Red supergiant
In 2022, Joe Diego of Cantabria UniversityThe team found a red supergiant, a star that has never been seen outside our universe. The Webb Space Telescope can identify it with its infrared sensor.[4]
