Eta Carinae, known in the west asShip baseη (η Carinae) star is a very high qualityHigh luminosity blue variable star[1], should be abinary star 。The mass is about 100 M ⊙, and the brightness is about 4.6 million L ⊙, which is about 7500 ly away from the earth.The activity is extremely unstable, and there are often huge eruptions, during which even its shape will change fromsphericalIt becomes a flat dumbbell.This one was taken in 1996 through the complicatedimage processing The later image can show the fine parts of the cloud around the naughty star, including two clear round projections, a hot central region, and some strange radial stripes.Two round projections filled with gas and dust are absorbing blue light andultraviolet rays。Those strange radial stripes are still unexplained.Maybe these clues will tell us how the nebula was formed, or maybe they will tell us when Haishan II will explode.
Chinese name
Haishan II/ship base η star
Foreign name
Eta Carinae
Alias
Eta Car / η Carinae / η Car
Classification
A: High luminosity blue variable star B: main sequence star
Haishan II（Eta Carinae）Is located inShip baseOne ofStellar system(Right ascension 10 h 45.1 mDeclination− 59 ° 41m), which is about 7500 to 8000 light years away from the sun. It is difficult to see in the area north of 27 ° north latitudeSouth Latitude30 ° is oneArched polar star。This system has at least two stars, one of which is located in the early stage of star life, and its mass is about 150 times that of the sunHigh luminosity blue variable star(LBV), and at least 30 have been lostSolar mass。Although it is believed that there is anotherWolf RayetSurrounded by its largercompanionHowever, it is difficult to directly discover the huge and thick red nebula surrounding the seamount.Its overall luminosity is about 5.5 million times that of the sun, and the mass of the system is estimated to be more than 150 times that of the sun[2]。Due to its mass and life stage, it is expected that it will explode into aPolar supernovaThe estimate is one million years from now.
Seamount II is the closest star to the Earth among the massive stars, located inShip base。The distance from the earth is 7500~8000 ly, so astronomers can learn many details about this object.According to the data of various wave bands, Haishan II is determined to be one of the objects with the highest brightness known.Sent by Haishan IIultravioletThe color is purple by reflection, and the expanding gas double valve is streaked with dark dust.[3]
The brightness of Haishan II is close toEddington luminosityThe external radiation pressure is almost strong enough to counteract gravity.If the mass of stars exceeds the limit of Eddington luminosity, their gravity can only barely restrain radiation and gas, and may lead toSupernovaOr extreme supernovae.
Two seamountsHigh qualityThe stars of.In the past history, Seamount II has several records of sharp brightening and then darkening.During the short period of April 1843, Haishan II became the second bright star in the earth's night sky, with brightness only less thanSirius, although its distance is 7500ly, or 870 times the distance of Sirius.Astronomers believe that Haishan Two Stars will probably happen in the next few hundred thousand yearsSupernova explosion。 In addition, the massive Hasan II star is also a possible candidate object for Hypernova, that is, it may be the futuregamma ray Source of explosion.1841 was the highest recorded activity peak of Haishan Two Stars.During this period, the brightness was even higher than Sirius, so that people could see this star in the daytime.Haishan Erxing is in the late stage of development and its activities are declining.A largePlanetary nebula——OneHomunculus Nebula 。However, Haishan II continues to erupt violently.It is generally believed that it will eventually become a gorgeousSupernova, debris is black hole or no debris
Observation history
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X-ray composite image of Haishan II (blue and orange)
The most striking feature of Hasan II is the change of brightness, which is divided into Luminous Blue Variable (LBV) binary stars.
Haishan II was first recorded by Edmund Halley in 1677, when it was a fourth class star, but by 1730,ObserverNotice that it has become quite bright, becoming one of the most dazzling stars in Carina.Seamount II then darkened again, returning to its original gloom in 1782, but it began to brighten again in 1820.By 1827, Hasan II had become more than 10 times brighter, and reached its peak in April 1843, with a brightness of -0.83, ranking the second brightest star in the sky, second only to the star with a distance of 8.6 lySirius。
The activity of Haishan-2 is extremely unstable, and it often occurs an extraordinary eruption, during which even its shape will become irregular.The most recent eruption of Hasan II almost reached its peak in 1841, but the cause of the eruption is still unknown.Astronomers speculate that it may be caused by the huge luminosity on the seamountRadiation pressureCaused by.Haishan II became dark again after 1843. During 1900~1940, its brightness was only 87.9, so it could not be usedVisual observationTo.
In the summer of 2003, Haishan II experienced a spectral minimum.Scientists once organized a huge observation activity, including using all available ground (such asCCDPhotometric analysis）AndSpace telescope, such as the Hubble Space Telescope, Chandra X-rayobservatory、International Gamma Ray Astrophysics LaboratoryAndVery large telescope。The main purpose of these observation activities is to determine whether Haishan-2 is a pairKonductraIf it is a pair of binary stars, try to identify their companion stars, determine the cause of this phenomenon, and understand the relationship between them (if they are binary stars) and the 19th century explosion.
The spectral observation of Hasan II shows that some divergenceSpectral lineIn the past, it darkened periodically every 5.52 years, and this period lasted steadily for decades.The radio divergence spectrum and X-ray luminosity of Hasan II will also decline when these "events" occur.These changes are related toultraviolet raysThe observation of Haishan-2 shows that it is very likely that Haishan-2 is indeed a pair of binary stars, and the companion star is a hot but small star with a period of 5.52 yearsEccentricityOfElliptical orbit。
The brightness of Haishan-2 suddenly doubled between 1998 and 1999, but in 2007, it was easily observed with the naked eye, and the brightness of Haishan-2 was close to 5.
In 2012, the Hubble Space Telescope released the full picture of the Homunculus Nebula formed by the eruption of Haishan II.[9]
Future forecast
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Haishan II is in the late stage of development and its activities are declining.A large dumbbell shaped planetary nebula has formed on its periphery[4]
The evolutionary path and age of seamount II have not been determined, so the explosionPossibleMillions of years later, or tens of thousands of years later, the light of explosion may already be spreading.For example, Haishan II may be an evolutionary stage of super massive stars, and the main theory is that they will show extreme mass loss, andSupernova explosionPreviously, they took off their shells and became a hot Wolf Rayet star, but if they could not retain their mass, they would become extremely supernovae.
Huge stars like Hyacinth II will run out of fuel very quickly because they must emit a high degree of light.Haishan II is predicted to become a supernova or extreme supernova, but its evolutionary path and age have not yet been determined, so the explosion may occur 1 million years later or tomorrow.Luminous Blue Variables such as Hasan II may be an evolutionary stage of stars with super large mass. The main theory is that they will show extreme mass loss and become a Wolf Rayet star before the supernova explosion. However, if they cannot retain their mass, they will become extremely supernovae[5]。
Except Haishan II,SN 2006jcIs the closest known star of this type to the Earth, 77 million light-years away, located atlynxOfUGC 4904[6]。It suddenly brightened on October 20, 2004, when a JapaneseAmateur astronomerYoichi Itagaki exploded as a supernova.However, it did not really explode at that time, but did not explode until two years later (October 9, 2006).So at first it was aPseudosupernovaAt first, the eruption ejected 0.01 solar mass (more than 20 timesJupiterMass) into space.
Because Haishan II is quite similar to SN 2006jcNASAStefan Immler of Goddard Launch Center believes that this star will explode in decades or even years.howeverUniversity Of California Stanford Woosley disagrees with this statement. He thinks that Seamount II may be in the early stage of evolution, because it still has several elements that cannuclear fusion。
Another recently observed supernova explosion isSN 2006gyIt is located at a distance of 238 million light years from the earthNGC 1260spiral galaxyWas found on September 18, 2006.Many astronomers believe that the explosion mechanism of SN 2006gy may be quite similar to the fate that Admiral Haishan II will face.
Haishan-2 is only 7500 light-years away from Earth, so when it has a supernova explosion or extreme supernovaDuring explosionIt may affect the earth, but it is unlikely to directly affect human beings, becauseatmosphereIt will block the outsideGamma ray。The impact scope of this impact is likely to be limited to the upper atmosphere, which includesozone layer、spacecraft、Artificial satelliteAnd astronauts.At least one scientist claims that if Haishan II evolves into a supernova or extreme supernova, "it will be bright enough to be seen even in the daytime, and even to read books by the light it produces at night[7]”。The supernova or extreme supernova explosion caused by Haishan II is likely to be emitted from the polesGamma ray burst。Since scientists found that Haishan-2 is at least onebinary star , evenTriadAfter the system, this may increase or decrease its strength when it becomes a supernova or extreme supernova[8]。
