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[[Image:Sol.jpg|thumb|right|200px|A star]]
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[[File:Sol.jpg|thumb|A star]]
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{{disambiguation|Earth's sun|Sol|rd=Sun}}
A '''star''' (or "'''sun'''") is an [[energy]]-producing sphere of [[plasma]] and [[gas]]. The region around a star that is held by its [[gravity]], including any [[planet]]s, [[moon]]s, [[comet]]s, and [[asteroid]]s, is called a [[star system]].
 
  +
{{disambiguation|the actress|Star (actress)}}
 
A '''star''' (or "'''sun'''") is a massive [[energy]]-producing sphere of [[plasma]] and [[gas]] located in [[space]]. The region around a star that is held by its [[gravity]], including any [[planet]]s, [[moon]]s, [[comet]]s, and [[asteroid]]s, is called a [[star system]].
   
 
==Stellar life cycle==
 
==Stellar life cycle==
 
===Formation===
 
===Formation===
Stars are born out of huge gaseous [[nebula]]e. Inside these nebulae, centers of higher density form, slowly accumulating more mass as the center's gravity increases, to form a [[protostar]]. Pressure in the interior of the protoster rises, in turn increasing the density and temperature until the gas turns to plasma, where the atomic nuclei and the [[electron]]s are dissociated from each other. At a sufficient temperature and pressure, [[nuclear fusion]] is initiated at the core, producing light: the star is born.
+
Stars are born out of huge gaseous [[nebula]]e. Inside these nebulae, centers of higher density form, slowly accumulating more mass as the center's gravity increases, to form a [[protostar]]. [[Pressure]] in the interior of the protostar rises, in turn increasing the density and temperature until the gas turns to plasma, where the atomic nuclei and the [[electron]]s are dissociated from each other. At a sufficient temperature and pressure, [[nuclear fusion]] is initiated at the core, producing light: the star is born.
[[Image:Risa sunset.JPG|thumb|200px|The two suns of Risa]]
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[[File:Risan_sunset.jpg|thumb|The two suns of Risa]]
  +
 
===Star evolution===
 
===Star evolution===
 
Stars can be made up of various different elements depending on their age.
 
Stars can be made up of various different elements depending on their age.
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Young stars mainly consist of [[hydrogen]], which is fused to [[helium]] thereby increasing the star's helium ratio over time and producing large quantities of energy. This energy, in turn, creates extreme pressure, preventing the star from collapsing under its own gravity.
 
Young stars mainly consist of [[hydrogen]], which is fused to [[helium]] thereby increasing the star's helium ratio over time and producing large quantities of energy. This energy, in turn, creates extreme pressure, preventing the star from collapsing under its own gravity.
   
*Dr. [[Tolian Soran]] used a [[Trilithium]] weapon in [[2371]] to stop all fusion reactions inside the [[Amargosa]] sun, thereby collapsing the star and altering the gravitational conditions in the system. (''[[Star Trek: Generations]]'')
+
*Dr. [[Tolian Soran]] used a [[trilithium]] weapon in [[2371]] to stop all fusion reactions inside the [[Amargosa]] sun, thereby collapsing the star and altering the gravitational conditions in the system. ({{film|7}})
   
 
As a sun gets older it begins to fuse heavier elements, like helium, as the lighter elements like hydrogen are depleted. This, however, releases more energy, causing the star to swell, which increases its surface area from which the energy is emitted. This phase marks the beginning of the star's end.
 
As a sun gets older it begins to fuse heavier elements, like helium, as the lighter elements like hydrogen are depleted. This, however, releases more energy, causing the star to swell, which increases its surface area from which the energy is emitted. This phase marks the beginning of the star's end.
   
*In [[2367]], Dr. [[Timicin]] of the planet [[Kaelon II]] tried to save the dying star [[Kaelon]] by regulating its ever-increasing temperature with the bombardment of [[photon torpedoes]]. However, the experiment failed after testing the procedure with a star in an uninhabited solar system. ([[TNG]]: "[[Half a Life]]")
+
*In [[2367]], Dr. [[Timicin]] of the planet [[Kaelon II]] tried to save the dying star [[Kaelon]] by regulating its ever-increasing temperature with the bombardment of [[photon torpedo]]es. However, the experiment failed after testing the procedure with a star in an uninhabited solar system. ({{TNG|Half a Life}})
   
 
Because of its larger surface area, the star turns red and is then called a [[red giant]]. After the sun runs out of light elements and the number of fusion reactions decreases, its own gravity causes it to collapse and to expel its outer layers of matter, creating beautiful "planetary nebulae". The remnant of the star is called [[white dwarf]].
 
Because of its larger surface area, the star turns red and is then called a [[red giant]]. After the sun runs out of light elements and the number of fusion reactions decreases, its own gravity causes it to collapse and to expel its outer layers of matter, creating beautiful "planetary nebulae". The remnant of the star is called [[white dwarf]].
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Every star has to pass these stages of evolution. However, depending on their masses, some suns experience further changes.
 
Every star has to pass these stages of evolution. However, depending on their masses, some suns experience further changes.
   
Below 1.5 [[Sol]] masses: After 1-10 billion years any nuclear reactions inside the white dwarf finally cease and the star turns to a "black dwarf", a very small stellar corpse.
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Below 1.5 [[Sol]] masses: After one to ten billion years any nuclear reactions inside the white dwarf finally cease and the star turns to a "black dwarf", a very small stellar corpse.
   
*In [[2370]], the [[USS Prometheus|USS ''Prometheus'']] hosted Dr. [[Gideon Seyetik]]'s succesful attempt to re-ignite the stellar corpse [[Epsilon 199]] by using a [[protomatter]]-laden shuttlepod remotely sent into the star. In the case of a failure, the star could have exploded in a supernova instead. ([[DS9]]: "[[Second Sight]]")
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*In [[2370]], the {{USS|Prometheus|NCC-71201}} hosted Dr. [[Gideon Seyetik]]'s successful attempt to re-ignite the stellar corpse [[Epsilon 119]] by using a [[protomatter]]-laden shuttlepod remotely sent into the star. In the case of a failure, the star could have exploded in a supernova instead. ({{DS9|Second Sight}})
   
Above 1.5 Sol masses: The white dwarf swells again, fusing all elements up to [[iron]]. After the last iron is depleted, the star turns into a [[supernova]], where the outer layers of the sun explode, which, in turn, causes a massive shock wave. The remains of this explosion are a vast matter nebula and a tiny [[neutron star]], which is so dense, that all [[proton]]s and [[electron]]s are neutralized to [[neutron]]s. A special form of neutron stars are [[pulsar]]s.
+
Above 1.5 Sol masses: The white dwarf swells again, fusing all elements up to [[iron]]. After the last iron is depleted, the star turns into a [[supernova]], where the outer layers of the sun explode, which, in turn, causes a massive [[shock wave]]. The remains of this explosion are a vast matter nebula and a tiny [[neutron star]], which is so dense, that all [[proton]]s and [[electron]]s are neutralized to [[neutron]]s. A special form of neutron stars are [[pulsar]]s.
   
*In [[2269]], the star [[Beta Niobe]] turned to a supernova, when crewmembers of the [[Federation]] [[starship]] [[USS Enterprise (NCC-1701)|USS ''Enterprise'']] were almost trapped on its planet [[Sarpeidon]]. ([[TOS]]: "[[All Our Yesterdays]]")
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*In [[2269]], the star [[Beta Niobe]] turned to a supernova, when crewmembers of the [[Federation]] [[starship]] {{USS|Enterprise|NCC-1701}} were almost trapped on its planet [[Sarpeidon]]. ({{TOS|All Our Yesterdays}})
   
*The resulting electro-magnetic pulse from the supernova of [[Beta Magellan]] in [[2364]] was so feared by the computer-dependent [[Bynar]] in the nearby [[Beta Magellan system]] that they commandeered the [[USS Enterprise (NCC-1701-D)|USS ''Enterprise''-D]] as a temporary dump for their planetary [[computer]]. ([[TNG]]: "[[11001001]]")
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*The resulting electromagnetic pulse from the supernova of [[Beta Magellan]] in [[2364]] was so feared by the computer-dependent [[Bynar]] in the nearby [[Beta Magellan system]] that they commandeered the {{USS|Enterprise|NCC-1701-D|-D}} as a temporary dump for their planetary [[computer]]. ({{TNG|11001001}})
   
*In [[2373]], a series of supernovae witnessed by the [[USS Voyager|USS ''Voyager'']] in the [[Delta Quadrant]] turned out to be the real-time result of "battles" during a civil war in the [[Q Continuum]]. They were actually created by spatial disruptions in the Continuum, which created a negative-density false vacuum that sucked nearby matter into the Continuum. ([[VOY]]: "[[The Q and the Grey]]")
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*In [[2373]], a series of supernovae witnessed by the {{USS|Voyager}} in the [[Delta Quadrant]] turned out to be the real-time result of "battles" during a civil war in the [[Q Continuum]]. They were actually created by spatial disruptions in the Continuum, which created a negative-density false vacuum that sucked nearby matter into the Continuum. ({{VOY|The Q and the Grey}})
   
 
If the remnant of a supernova is more massive than 2.5 Sol masses, it collapses to a [[black hole]].
 
If the remnant of a supernova is more massive than 2.5 Sol masses, it collapses to a [[black hole]].
   
 
==Stellar classification==
 
==Stellar classification==
Stars are assigned to different [[Spectral class|spectral classes]].
+
Stars are assigned to different [[spectral class]]es.
  +
===Parts of stars===
 
  +
* [[corona]]
Furthermore, a plot of stellar luminosities versus stellar spectral types on two axes, is called the [[Hertzsprung-Russell diagram]].
 
  +
* [[stellar core]]
  +
* [[chromosphere]]
   
 
===Types of stars===
 
===Types of stars===
 
*[[Protostar]]
 
*[[Protostar]]
 
*Star
 
*Star
**[[Red giant]]
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**[[Flare star]]
**[[White dwarf]]
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**[[F-type star]]
**[[Red dwarf]]
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**[[G-type star]]
  +
**[[Hypergiant]]
 
**[[Neutron star]]
 
**[[Neutron star]]
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**[[O-type star]]
 
**[[Pulsar]]
 
**[[Pulsar]]
**[[Flare star]]
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**[[Red dwarf]]
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**[[Red giant]]
 
**[[Supergiant]]
 
**[[Supergiant]]
  +
**[[T-Tauri type|T-Tauri type star]]
  +
**[[White dwarf]]
  +
**[[Yellow dwarf]]
 
*[[Black hole]]
 
*[[Black hole]]
   
 
==See also==
 
==See also==
 
*[[Stars and stellar bodies]]
 
*[[Stars and stellar bodies]]
  +
*[[Unnamed stars]]
  +
   
 
[[Category:Astronomical objects]]
 
[[Category:Astronomical objects]]
  +
[[Category:Stars| Star]]
 
 
[[de:Stern]]
 
[[de:Stern]]
  +
[[fr:Étoile]]
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[[it:Stella]]
  +
[[ja:恒星]]
  +
[[nl:Ster]]
  +
[[sr:Звијезда]]

Revision as of 18:46, 23 October 2015

Sol

A star

Sun redirects here; for Earth's sun, please see Sol.
For the actress, please see Star (actress).

A star (or "sun") is a massive energy-producing sphere of plasma and gas located in space. The region around a star that is held by its gravity, including any planets, moons, comets, and asteroids, is called a star system.

Stellar life cycle

Formation

Stars are born out of huge gaseous nebulae. Inside these nebulae, centers of higher density form, slowly accumulating more mass as the center's gravity increases, to form a protostar. Pressure in the interior of the protostar rises, in turn increasing the density and temperature until the gas turns to plasma, where the atomic nuclei and the electrons are dissociated from each other. At a sufficient temperature and pressure, nuclear fusion is initiated at the core, producing light: the star is born.

Risan sunset

The two suns of Risa

Star evolution

Stars can be made up of various different elements depending on their age.

Young stars mainly consist of hydrogen, which is fused to helium thereby increasing the star's helium ratio over time and producing large quantities of energy. This energy, in turn, creates extreme pressure, preventing the star from collapsing under its own gravity.

As a sun gets older it begins to fuse heavier elements, like helium, as the lighter elements like hydrogen are depleted. This, however, releases more energy, causing the star to swell, which increases its surface area from which the energy is emitted. This phase marks the beginning of the star's end.

  • In 2367, Dr. Timicin of the planet Kaelon II tried to save the dying star Kaelon by regulating its ever-increasing temperature with the bombardment of photon torpedoes. However, the experiment failed after testing the procedure with a star in an uninhabited solar system. (TNG: "Half a Life")

Because of its larger surface area, the star turns red and is then called a red giant. After the sun runs out of light elements and the number of fusion reactions decreases, its own gravity causes it to collapse and to expel its outer layers of matter, creating beautiful "planetary nebulae". The remnant of the star is called white dwarf.

Every star has to pass these stages of evolution. However, depending on their masses, some suns experience further changes.

Below 1.5 Sol masses: After one to ten billion years any nuclear reactions inside the white dwarf finally cease and the star turns to a "black dwarf", a very small stellar corpse.

Above 1.5 Sol masses: The white dwarf swells again, fusing all elements up to iron. After the last iron is depleted, the star turns into a supernova, where the outer layers of the sun explode, which, in turn, causes a massive shock wave. The remains of this explosion are a vast matter nebula and a tiny neutron star, which is so dense, that all protons and electrons are neutralized to neutrons. A special form of neutron stars are pulsars.

  • In 2373, a series of supernovae witnessed by the USS Voyager in the Delta Quadrant turned out to be the real-time result of "battles" during a civil war in the Q Continuum. They were actually created by spatial disruptions in the Continuum, which created a negative-density false vacuum that sucked nearby matter into the Continuum. (VOY: "The Q and the Grey")

If the remnant of a supernova is more massive than 2.5 Sol masses, it collapses to a black hole.

Stellar classification

Stars are assigned to different spectral classes.

Parts of stars

Types of stars

See also