Image source: European Space Agency (ESA)/ National Aeronautics and Space Administration (NASA) and Hubble Space Telescope Database (HLA), by Judy? Schmidt's creation
This kind of destiny takes a hand, just like all other sun-like stars whose mass is 40%-800% of the mass of the sun. But this picture is not a planetary nebula, but a short special stage before the formation of the nebula: the forward star (or protoplanetary) nebula.
Image source: National Aeronautics and Space Administration (NASA)/Jet Propulsion Laboratory (JPL)
At the end of this huge period, stars begin to shed their outer (hydrogen) layers, which will increase the temperature of the stars, because hydrogen is still merging with the helium shell of the stars.
Image source: European Space Agency (ESA)/Hubble Telescope, National Aeronautics and Space Administration (NASA).
The star in the middle becomes bluer and hotter, causing strong winds.
Image source: European Space Agency (ESA)/National Aeronautics and Space Administration (NASA)
These wind energies lead to bipolar (multi-node) jets and bow shock waves.
Image source: European Space Agency (ESA)/National Aeronautics and Space Administration (NASA)/Hubble Telescope/Jet Propulsion Laboratory (JPL).
When the temperature of a star rises above 30,000 Kelvin, the surrounding ejecta will be ionized, producing radiation and reflection.
Image source: European Space Agency (ESA)/Hubble Telescope, National Aeronautics and Space Administration (NASA).
Although the pre-(protoplanet) period of planetary nebulae is very short (about 10000), it is very common, and there are countless examples in our galaxy alone.
A star is a celestial body composed of luminous spheres formed by plasma gathering together through its own gravity. The nearest star to the earth is the sun. At night on earth, many other stars are also visible to the naked eye, because they are very far away from the earth, so they only appear in the form of a large number of fixed bright spots in the night sky. Historically, some of the most famous stars have been divided into constellations and constellation groups, and the brightest stars in each group have official names. Astronomers put together a list of stars, and use this information to identify known stars and provide standardized star designs. Hubble volume contains about 1? 10 24 stars, but most of them are invisible to the naked eye on earth, covering our galaxy? Galaxy? All the stars except.
At least a part of a star's life is radioactive, because there is a nuclear fusion reaction between hydrogen and helium at its core, which releases energy through the star and then radiates into space. Almost all natural elements heavier than helium are produced by nuclear synthesis during the lifetime of stars, and some of them are produced by nuclear synthesis during supernova explosions. When a star comes to the end of its life, it may also contain degraded matter. Astronomers can determine the mass, age, metallicity (chemical composition) and other properties of a star by observing its trajectory, luminosity and spectrum in space respectively. The total mass of a star is the main factor that determines its evolution and ultimate fate. Other characteristics can also change its life, such as diameter and temperature; At the same time, the environment of a star will also affect its rotation and motion. With the surface temperature of many stars as one coordinate axis and the luminosity as the other coordinate axis, the image is called hertzsprung? Russell diagram (Herotto diagram). There are also some Herodotus diagrams that add the age axis and evolution state axis of some special stars.
In addition to mass, elements heavier than helium also play a vital role in the evolution of stars. Astronomers have labeled all elements heavier than helium? Metal? And determine the chemical concentration of these elements in the star, that is, the degree of metallicity. The metallicity of a star will affect when it starts to burn fuel and control the formation of magnetic field, which will also have an impact on the star wind. In fact, the second group of older stars has lower metal content than the first group of younger stars because the chemical composition of the molecular clouds they form is different. As time goes by, more and more heavy elements appear in these molecular clouds after the long star dies and leaves part of the atmosphere.