The formation of type Ia supernova requires abinary star , one isSuperStar, one isWhite dwarf。The massive white dwarf absorbs the material of the giant star (mainlyhydrogen）, when up to 1.44Solar massCarbon detonation will occur, and there is no product left after nuclear explosion.
Chinese name
Ia type supernova
Foreign name
one-A supernova
Conditions
Double star system formed by white dwarfs and giant stars
Purpose
Measuring the distance between two objects in the universe
Cause of explosion
The ejected electron photons transform the outer layer of the heavy element sodium magnesium outer layer of the star, producing high temperature and high pressure, forming more heavy element metal electrostatic metal hail, which continues to impact the center of the star, damaging the outer sheath of the star, thickening the pressure of the outer sodium magnesium layer, forming more heavy elements of gold and strontium, and bursting out suddenly.Type ia supernova.
In the 1960s, scientists proposed thatfixed starOfElectronic degeneracyIt can be approvedthermonuclearCombustion excitationThermonuclear explosionAnd explode the whole celestial body.After nearly 50 years of research, scientists have generally accepted the following picture at the beginning of the 21st century, that is, type Ia supernova comes from carbon and oxygen in the binary systemWhite dwarfThermonuclear explosion.Carbon oxygen white dwarf starscompanionaccretion The material thus increases its own mass. When its mass increases to its maximum stable mass limit, its center will stimulate unstable thermonuclear combustion, releasing enough energy to explode the entire carbon oxygen white dwarf and generate a large amount ofradioactivityelementnickel, nickel and its radioactive nucleonicRadioactive decayThe energy injected into the projectile heats it, making Type Ia supernovae look so bright.
Main conditions
Supernova debris 13000 light-years from Earth
1. There is aSupernovaOfWhite dwarfAnd onecompanion(Another star in the binary system).The so-called white dwarf is the remnant form of a star like the sun after burning up.Another companion star could beMain sequence star(Like the sun, there is stability insidenuclear fusionStar), orRed GiantAnd white dwarfs.
2. There is gas transport from the companion star to the white dwarf star, so the mass of the white dwarf star is increasing
3. When the mass of the white dwarf star increases to 1.4 times of the sun, the nuclear fusion is ignited again. The nuclear fusion reaction in this period is extremely rapid, so a big explosion occurs (similar to the above“Zombie Planet”）Since the mass of the white dwarf is always 1.4 times that of the sun when it explodes, its luminosity is certain.[1]
features
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Halos from Type IA Supernovae
With the improvement of observation technology, researchers have found more and more Type Ia supernovae, and found that about half of Type IA supernovae have a delay time of less than 100 million years (the delay time of Type IA supernovae refers to the time interval from the formation of the binary system to the explosion of Type Ia supernovae).This means that there are still younger IA type supernovae.
Scientists believe that the existence of young IA type supernovae may affect the chemistry of existing galaxiesEvolutionary modelThe impact is caused bySupernova explosionLater, they will produce a large amount of iron earlier and feed it backHost galaxy。[2]
On July 2, 2011, according to foreign media reports, "zombie" stars are usually the lastMartyrdom explosionTo end everything, but it can "bring the dead back to life" by engulfing the surrounding stars.This kindSupernovaIt is a very special kind of celestial body in the universe, which is called type IA supernova in astronomy.The reason why Ia supernovae are called "zombie" stars is that their cores are dead.However, they can eat aroundcompanionThe substance of the dead comes back to life.In the past 50 years, astronomers have found that type IA supernovae are morebinary star Two celestial bodies circle each other, and one of them sucks the material of the other to achieve the goal of reincarnation.At the same time, it is also the epitome of the end of life of the sun, which has shrunk to the size of the earth.
Predecessor star model
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Supernova explosion simulation diagram
The current popular Ia type supernovaPredecessor starThere are two main models, one is carbon and oxygenWhite dwarfOfaccretion The other is the combination model of carbon and oxygen white dwarfs.
The accretion model of carbon and oxygen white dwarfs means that a carbon and oxygen white dwarf starMain sequence star、SubgiantOr oneRed GiantAccretion material, the accreted material burns stably on the surface of the carbon oxygen white dwarf star, gradually increasing the mass of the white dwarf star. When the mass of the white dwarf star reaches its maximum stable mass limit, the carbon in the center of the white dwarf star is ignited, and the released nuclear energy instantly explodes the white dwarf star, resulting in the IA type supernova phenomenon.
The merging model of carbon and oxygen white dwarfs refers to that two carbon and oxygen white dwarfs revolve around each other becauseGravitational waveRADIATION EXTRACTION OF DOUBLE STAR SYSTEM ORBITSangular momentum, make the binary stars close to each other, and finally synthesize a new carbon oxygen white dwarf. If the total mass of this new carbon oxygen white dwarf exceeds the maximum stable mass limit, it will also occur similar to carbon oxygenWhite dwarf accretionModel likenuclear fusion。
Academic status
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Type IA supernova as the universe“Standard candle”The position of "" mainly comes from (or partly depends on) the assumption that they are very similar to each other and form a unified class of celestial bodies.At the beginning of the 21st century, people observed the difference between type IA supernovae.Maeda et al. put forward a new model, which takes into account the recent theoretical and observational data, and interprets the observed spectral diversity as a consequence of random directions - an asymmetric explosion theoretically proposed is observed from these directions.On this basis, spectral evolution diversity is no longer a problem in continuing to use IA type supernovae as "standard candles".
scientific research
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In 2022, American astrophysicists, through the analysis called Pantheon+,Confirming that the universe is composed of about two-thirds of dark energy and one-third of matter,Pantheon+Including more than 1500 stellar explosions called Type Ia supernovae.[3]
On December 20, 2022, it was learned from the Yunnan Astronomical Observatory of the Chinese Academy of Sciences that the researchers of the observatory revealed the material loss mechanism and main observation characteristics of the predecessor star of Type Ia supernova by using hydrodynamic simulation, which provided theoretical guidance for the follow-up observation and search work.Relevant achievements were published in the international journal Astronomy and Astrophysics.[4]
Astronomical significance
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At the end of the 20th century, the ranging research of type IA supernovae made people realize that the universe is expanding at an accelerated speed, thus inferring thatDark energyThe exists of.This is not only a breakthrough in astronomy, but also a breakthrough in physics.Type IA supernova has been listed as one of the main objects of star research in the past decade by the New Millennium Astronomy and Astrophysics of the United States due to its special position in cosmology.
From this point of view, dark energy may be an attribute of a space,Cosmic spaceIt is related to some energies, which can also explain why such large-scale dark energy is distributed in the universe. Of course, this is also a hypothesis.However, the breakthrough of all this lies in type Ia supernovae.The astrophysical community will conduct a detailed study of Ia type supernovae. From the explosion model to the evolution path, the secret of dark energy will be revealed one day.
