Stars
Stars light up our universe and make it alife. The stars may be grouped by their size and mass, which determine star's properties, longevity and destiny. The smaller the star is the longer it exists, the bigger - the shorter its lifespan. This is because the most massive stars host much higher pressures and temperatures in their cores and nuclear reaction within them proceed at rapid rate. Lower-mass stars, in contrast, burn and consume their fuel slowly. Thus, dwarfs exist for billions and even trillion years, middle size stars like our sun - several billion years, massive and supermassive stars - millions of years.
Dwarfs are not only the most long-lived, but also the most videspread type of stars and billlions of them are scattered around the milky way only.
The core process in the star is nuclear fusion which makes stars shine. The most important property of the star is the balance between internal star's gravity and outward pressure. However, as the star uses its hydrogen, and forms heavy elements, such as iron, in its core, the balance gets disrupted. Finally, the outward pressure is not able to withstand the internal pull, the core of the star collapses to a critical point, where it overcomes even fundamental forces of repulsion between subatomic particles, and the star explodes.
1. Brown dwarfs : Failed stars, did not have enough mass for the constant nuclear reactions to occur. Glow slightly for billions to trillion of years unless fade away.
2. Red dwarf : Shine for billions of years unless use most of their nuclear fuel, then the core collapses into a white dwarf and glows slightly until fades away, for up to 10 in power of 34 years.
3. Middle size stars like our sun : Nuclear reactions within the star transform its hydrogen into helium and heavy elements. This process continues for several billion years. When a star loses balance between internal gravity and outward pressure, it begins to grow in size into a red giant. The core condenses, while the outer layers swell and turn red. When the core collapses to a critical point, the star explodes into planetary nebula (which is formed of various gases). In the centre of planetary nebula the core of the star collapses into a white dwarf. Such white dwarf will glow slightly until decentegrates.
4. Massive stars : Massive stars live for millions of years unless they explode into a supernova. Supernova consists of enriched gases, from which nebula will form and then new generation of stars will ignite. In the centre of supernova the core of the massive star will collapse into a neutron star.
As the balance between internal gravity and outward pressure in massive stars gets disrupted, the core of the star gets pressed to the point where protons and electrons combine and make neutrons. Thus, neutron star is made mostly of neutrons and has extremely large mass. In fact, a cube sugar of neutron star will weigh roughly a hundred million of tonnes on the earth. This is because the matter in the massive star becomes extremely compressed due to the dissruption of the balance between the pull and pressure. Due to such extreme density neutron stars have extreme gravity, incredibly strong magnetic fields and spin at extreme speed.
Some of neutron stars spread beams of radiation and are called pulsars. As neutron stars rotate at exremely high speed and have extreme gravity, spin produces strong magnetic field. Thus, spin axes of Neutron star emit radiation, which may be observed as a constant beam of light. From Earth light appears to pulse as the beam passes.
The other famous kind of neutron stars are magnetars which have the biggest magnetic field. Any disruption of the neutron star's compressed crust can produce an explosive release of electromagnetic radiation. One magnetar burst may release more energy in a second than our sun in a million years.
Neutron star will exist for an infinitely large period of time unless disintegrates.
4. The biggest supermassive stars : The biggest stars shine for million of years unless explode and collapse into black holes. While massive stars collapse into neutron stars with extremely large density and spread enriched gases around; the disruption of the balance between gravity and outward pressure in supermassive stars, makes their core compressed even more than in neutron stars. Their core continues collapsing in on itself until a black core is produced. Thus, black holes are objects where density is infenitenely big. Black holes are the most mysterious and interesting objects in our universe as it seems that within them the laws of physics as we know them stop. In particular, due to the infinite density of black holes nothing, even light cannot escape it.
However, black holes are not eternal. They will exist for 100 in the power of 100 years, but desintegrate slowly by the phenomena known as Hawking radiation.
Stars light up our universe and make it alife. The stars may be grouped by their size and mass, which determine star's properties, longevity and destiny. The smaller the star is the longer it exists, the bigger - the shorter its lifespan. This is because the most massive stars host much higher pressures and temperatures in their cores and nuclear reaction within them proceed at rapid rate. Lower-mass stars, in contrast, burn and consume their fuel slowly. Thus, dwarfs exist for billions and even trillion years, middle size stars like our sun - several billion years, massive and supermassive stars - millions of years.
Dwarfs are not only the most long-lived, but also the most videspread type of stars and billlions of them are scattered around the milky way only.
The core process in the star is nuclear fusion which makes stars shine. The most important property of the star is the balance between internal star's gravity and outward pressure. However, as the star uses its hydrogen, and forms heavy elements, such as iron, in its core, the balance gets disrupted. Finally, the outward pressure is not able to withstand the internal pull, the core of the star collapses to a critical point, where it overcomes even fundamental forces of repulsion between subatomic particles, and the star explodes.
1. Brown dwarfs : Failed stars, did not have enough mass for the constant nuclear reactions to occur. Glow slightly for billions to trillion of years unless fade away.
2. Red dwarf : Shine for billions of years unless use most of their nuclear fuel, then the core collapses into a white dwarf and glows slightly until fades away, for up to 10 in power of 34 years.
3. Middle size stars like our sun : Nuclear reactions within the star transform its hydrogen into helium and heavy elements. This process continues for several billion years. When a star loses balance between internal gravity and outward pressure, it begins to grow in size into a red giant. The core condenses, while the outer layers swell and turn red. When the core collapses to a critical point, the star explodes into planetary nebula (which is formed of various gases). In the centre of planetary nebula the core of the star collapses into a white dwarf. Such white dwarf will glow slightly until decentegrates.
4. Massive stars : Massive stars live for millions of years unless they explode into a supernova. Supernova consists of enriched gases, from which nebula will form and then new generation of stars will ignite. In the centre of supernova the core of the massive star will collapse into a neutron star.
As the balance between internal gravity and outward pressure in massive stars gets disrupted, the core of the star gets pressed to the point where protons and electrons combine and make neutrons. Thus, neutron star is made mostly of neutrons and has extremely large mass. In fact, a cube sugar of neutron star will weigh roughly a hundred million of tonnes on the earth. This is because the matter in the massive star becomes extremely compressed due to the dissruption of the balance between the pull and pressure. Due to such extreme density neutron stars have extreme gravity, incredibly strong magnetic fields and spin at extreme speed.
Some of neutron stars spread beams of radiation and are called pulsars. As neutron stars rotate at exremely high speed and have extreme gravity, spin produces strong magnetic field. Thus, spin axes of Neutron star emit radiation, which may be observed as a constant beam of light. From Earth light appears to pulse as the beam passes.
The other famous kind of neutron stars are magnetars which have the biggest magnetic field. Any disruption of the neutron star's compressed crust can produce an explosive release of electromagnetic radiation. One magnetar burst may release more energy in a second than our sun in a million years.
Neutron star will exist for an infinitely large period of time unless disintegrates.
4. The biggest supermassive stars : The biggest stars shine for million of years unless explode and collapse into black holes. While massive stars collapse into neutron stars with extremely large density and spread enriched gases around; the disruption of the balance between gravity and outward pressure in supermassive stars, makes their core compressed even more than in neutron stars. Their core continues collapsing in on itself until a black core is produced. Thus, black holes are objects where density is infenitenely big. Black holes are the most mysterious and interesting objects in our universe as it seems that within them the laws of physics as we know them stop. In particular, due to the infinite density of black holes nothing, even light cannot escape it.
However, black holes are not eternal. They will exist for 100 in the power of 100 years, but desintegrate slowly by the phenomena known as Hawking radiation.
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