Gargaz/Test · Datasets at Hugging Face

text stringlengths 8 3.87k
30.05866813659668 121 WikiText2
23450 On both apparent and absolute magnitude scales , the smaller the magnitude number , the brighter the star ; the larger the magnitude number , the fainter the star . The brightest stars , on either scale , have negative magnitude numbers . The variation in brightness ( ΔL ) between two stars is calculated by subtracting the magnitude number of the brighter star ( mb ) from the magnitude number of the fainter star ( mf ) , then using the difference as an exponent for the base number 2 @.@ 512 ; that is to say :
25.95981216430664 101 WikiText2
23451 <formula>
1999.70263671875 3 WikiText2
23452 <formula>
1999.70263671875 3 WikiText2
23453 Relative to both luminosity and distance from Earth , a star 's absolute magnitude ( M ) and apparent magnitude ( m ) are not equivalent ; for example , the bright star Sirius has an apparent magnitude of − 1 @.@ 44 , but it has an absolute magnitude of + 1 @.@ 41 .
36.28964614868164 60 WikiText2
23454 The Sun has an apparent magnitude of − 26 @.@ 7 , but its absolute magnitude is only + 4 @.@ 83 . Sirius , the brightest star in the night sky as seen from Earth , is approximately 23 times more luminous than the Sun , while Canopus , the second brightest star in the night sky with an absolute magnitude of − 5 @.@ 53 , is approximately 14 @,@ 000 times more luminous than the Sun . Despite Canopus being vastly more luminous than Sirius , however , Sirius appears brighter than Canopus . This is because Sirius is merely 8 @.@ 6 light @-@ years from the Earth , while Canopus is much farther away at a distance of 310 light @-@ years .
23.274019241333008 142 WikiText2
23455 As of 2006 , the star with the highest known absolute magnitude is LBV 1806 @-@ 20 , with a magnitude of − 14 @.@ 2 . This star is at least 5 @,@ 000 @,@ 000 times more luminous than the Sun . The least luminous stars that are currently known are located in the NGC 6397 cluster . The faintest red dwarfs in the cluster were magnitude 26 , while a 28th magnitude white dwarf was also discovered . These faint stars are so dim that their light is as bright as a birthday candle on the Moon when viewed from the Earth .
46.93743133544922 114 WikiText2
23456 = = Classification = =
856.6548461914062 5 WikiText2
23457 The current stellar classification system originated in the early 20th century , when stars were classified from A to Q based on the strength of the hydrogen line . It thought that the hydrogen line strength was a simple linear function of temperature . Rather , it was more complicated ; it strengthened with increasing temperature , it peaked near 9000 K , and then declined at greater temperatures . When the classifications were reordered by temperature , it more closely resembled the modern scheme .
39.83967590332031 86 WikiText2
23458 Stars are given a single @-@ letter classification according to their spectra , ranging from type O , which are very hot , to M , which are so cool that molecules may form in their atmospheres . The main classifications in order of decreasing surface temperature are : O , B , A , F , G , K , and M. A variety of rare spectral types are given special classifications . The most common of these are types L and T , which classify the coldest low @-@ mass stars and brown dwarfs . Each letter has 10 sub @-@ divisions , numbered from 0 to 9 , in order of decreasing temperature . However , this system breaks down at extreme high temperatures as classes O0 and O1 may not exist .
39.25697326660156 142 WikiText2
23459 In addition , stars may be classified by the luminosity effects found in their spectral lines , which correspond to their spatial size and is determined by their surface gravity . These range from 0 ( hypergiants ) through III ( giants ) to V ( main sequence dwarfs ) ; some authors add VII ( white dwarfs ) . Most stars belong to the main sequence , which consists of ordinary hydrogen @-@ burning stars . These fall along a narrow , diagonal band when graphed according to their absolute magnitude and spectral type . The Sun is a main sequence G2V yellow dwarf of intermediate temperature and ordinary size .
79.22908782958984 114 WikiText2
23460 Additional nomenclature , in the form of lower @-@ case letters added to the end of the spectral type to indicate peculiar features of the spectrum . For example , an " e " can indicate the presence of emission lines ; " m " represents unusually strong levels of metals , and " var " can mean variations in the spectral type .
50.00466537475586 66 WikiText2
23461 White dwarf stars have their own class that begins with the letter D. This is further sub @-@ divided into the classes DA , DB , DC , DO , DZ , and DQ , depending on the types of prominent lines found in the spectrum . This is followed by a numerical value that indicates the temperature .
72.82183837890625 61 WikiText2
23462 = = Variable stars = =
992.8522338867188 6 WikiText2
23463 Variable stars have periodic or random changes in luminosity because of intrinsic or extrinsic properties . Of the intrinsically variable stars , the primary types can be subdivided into three principal groups .
69.7124252319336 33 WikiText2
23464 During their stellar evolution , some stars pass through phases where they can become pulsating variables . Pulsating variable stars vary in radius and luminosity over time , expanding and contracting with periods ranging from minutes to years , depending on the size of the star . This category includes Cepheid and Cepheid @-@ like stars , and long @-@ period variables such as Mira .
51.39492416381836 70 WikiText2
23465 Eruptive variables are stars that experience sudden increases in luminosity because of flares or mass ejection events . This group includes protostars , Wolf @-@ Rayet stars , and flare stars , as well as giant and supergiant stars .
91.15422058105469 42 WikiText2
23466 Cataclysmic or explosive variable stars are those that undergo a dramatic change in their properties . This group includes novae and supernovae . A binary star system that includes a nearby white dwarf can produce certain types of these spectacular stellar explosions , including the nova and a Type 1a supernova . The explosion is created when the white dwarf accretes hydrogen from the companion star , building up mass until the hydrogen undergoes fusion . Some novae are also recurrent , having periodic outbursts of moderate amplitude .
49.07268142700195 89 WikiText2
23467 Stars can also vary in luminosity because of extrinsic factors , such as eclipsing binaries , as well as rotating stars that produce extreme starspots . A notable example of an eclipsing binary is Algol , which regularly varies in magnitude from 2 @.@ 3 to 3 @.@ 5 over a period of 2 @.@ 87 days .
44.449127197265625 64 WikiText2
23468 = = Structure = =
1031.75830078125 5 WikiText2
23469 The interior of a stable star is in a state of hydrostatic equilibrium : the forces on any small volume almost exactly counterbalance each other . The balanced forces are inward gravitational force and an outward force due to the pressure gradient within the star . The pressure gradient is established by the temperature gradient of the plasma ; the outer part of the star is cooler than the core . The temperature at the core of a main sequence or giant star is at least on the order of 107 K. The resulting temperature and pressure at the hydrogen @-@ burning core of a main sequence star are sufficient for nuclear fusion to occur and for sufficient energy to be produced to prevent further collapse of the star .
32.264991760253906 132 WikiText2
23470 As atomic nuclei are fused in the core , they emit energy in the form of gamma rays . These photons interact with the surrounding plasma , adding to the thermal energy at the core . Stars on the main sequence convert hydrogen into helium , creating a slowly but steadily increasing proportion of helium in the core . Eventually the helium content becomes predominant , and energy production ceases at the core . Instead , for stars of more than 0 @.@ 4 M ☉ , fusion occurs in a slowly expanding shell around the degenerate helium core .
42.723445892333984 102 WikiText2
23471 In addition to hydrostatic equilibrium , the interior of a stable star will also maintain an energy balance of thermal equilibrium . There is a radial temperature gradient throughout the interior that results in a flux of energy flowing toward the exterior . The outgoing flux of energy leaving any layer within the star will exactly match the incoming flux from below .
51.26933288574219 63 WikiText2
23472 The radiation zone is the region of the stellar interior where the flux of energy outward is dependent on radiative heat transfer , since convective heat transfer is inefficient in that zone . In this region the plasma will not be perturbed , and any mass motions will die out . If this is not the case , however , then the plasma becomes unstable and convection will occur , forming a convection zone . This can occur , for example , in regions where very high energy fluxes occur , such as near the core or in areas with high opacity ( making radiatative heat transfer inefficient ) as in the outer envelope .
35.801422119140625 115 WikiText2
23473 The occurrence of convection in the outer envelope of a main sequence star depends on the star 's mass . Stars with several times the mass of the Sun have a convection zone deep within the interior and a radiative zone in the outer layers . Smaller stars such as the Sun are just the opposite , with the convective zone located in the outer layers . Red dwarf stars with less than 0 @.@ 4 M ☉ are convective throughout , which prevents the accumulation of a helium core . For most stars the convective zones will also vary over time as the star ages and the constitution of the interior is modified .
33.85335159301758 117 WikiText2
23474 The photosphere is that portion of a star that is visible to an observer . This is the layer at which the plasma of the star becomes transparent to photons of light . From here , the energy generated at the core becomes free to propagate into space . It is within the photosphere that sun spots , regions of lower than average temperature , appear .
43.58253860473633 67 WikiText2
23475 Above the level of the photosphere is the stellar atmosphere . In a main sequence star such as the Sun , the lowest level of the atmosphere , just above the photosphere , is the thin chromosphere region , where spicules appear and stellar flares begin . Above this is the transition region , where the temperature rapidly increases within a distance of only 100 km ( 62 mi ) . Beyond this is the corona , a volume of super @-@ heated plasma that can extend outward to several million kilometres . The existence of a corona appears to be dependent on a convective zone in the outer layers of the star . Despite its high temperature , and the corona emits very little light , due to its low gas density . The corona region of the Sun is normally only visible during a solar eclipse .
33.98017120361328 151 WikiText2
23476 From the corona , a stellar wind of plasma particles expands outward from the star , until it interacts with the interstellar medium . For the Sun , the influence of its solar wind extends throughout a bubble @-@ shaped region called the heliosphere .
57.49843978881836 47 WikiText2
23477 = = Nuclear fusion reaction pathways = =
682.2861938476562 8 WikiText2
23478 A variety of nuclear fusion reactions take place in the cores of stars , that depend upon their mass and composition . When nuclei fuse , the mass of the fused product is less than the mass of the original parts . This lost mass is converted to electromagnetic energy , according to the mass @-@ energy equivalence relationship E = mc2 .
40.2259521484375 65 WikiText2
23479 The hydrogen fusion process is temperature @-@ sensitive , so a moderate increase in the core temperature will result in a significant increase in the fusion rate . As a result , the core temperature of main sequence stars only varies from 4 million kelvin for a small M @-@ class star to 40 million kelvin for a massive O @-@ class star .
39.00300216674805 70 WikiText2
23480 In the Sun , with a 10 @-@ million @-@ kelvin core , hydrogen fuses to form helium in the proton @-@ proton chain reaction :
143.03733825683594 32 WikiText2
23481 41H → 22H + 2e + + 2νe ( 2 x 0 @.@ 4 MeV )
397.0766906738281 18 WikiText2
23482 2e + + 2e- → 2γ ( 2 x 1 @.@ 0 MeV )
496.7121276855469 16 WikiText2
23483 21H + 22H → 23He + 2γ ( 2 x 5 @.@ 5 MeV )
376.552490234375 17 WikiText2
23484 23He → 4He + 21H ( 12 @.@ 9 MeV )
609.7614135742188 13 WikiText2
23485 These reactions result in the overall reaction :
452.8577880859375 8 WikiText2
23486 41H → 4He + 2e + + 2γ + 2νe ( 26 @.@ 7 MeV )
587.9017333984375 18 WikiText2
23487 where e + is a positron , γ is a gamma ray photon , νe is a neutrino , and H and He are isotopes of hydrogen and helium , respectively . The energy released by this reaction is in millions of electron volts , which is actually only a tiny amount of energy . However enormous numbers of these reactions occur constantly , producing all the energy necessary to sustain the star 's radiation output . In comparison , the combustion of two hydrogen gas molecules with one oxygen gas molecule releases only 5 @.@ 7 eV .
38.14534378051758 101 WikiText2
23488 In more massive stars , helium is produced in a cycle of reactions catalyzed by carbon called the carbon @-@ nitrogen @-@ oxygen cycle .
146.3300323486328 29 WikiText2
23489 In evolved stars with cores at 100 million kelvin and masses between 0 @.@ 5 and 10 M ☉ , helium can be transformed into carbon in the triple @-@ alpha process that uses the intermediate element beryllium :
151.573974609375 43 WikiText2
23490 4He + 4He + 92 keV → 8 * Be
1053.1519775390625 10 WikiText2
23491 4He + 8 * Be + 67 keV → 12 * C
990.353271484375 12 WikiText2
23492 12 * C → 12C + γ + 7 @.@ 4 MeV
666.370849609375 14 WikiText2
23493 For an overall reaction of :
666.8641357421875 6 WikiText2
23494 34He → 12C + γ + 7 @.@ 2 MeV
712.5584716796875 12 WikiText2
23495 In massive stars , heavier elements can also be burned in a contracting core through the neon burning process and oxygen burning process . The final stage in the stellar nucleosynthesis process is the silicon burning process that results in the production of the stable isotope iron @-@ 56 , an endothermic process that consumes energy , and so further energy can only be produced through gravitational collapse .
90.51050567626953 71 WikiText2
23496 The example below shows the amount of time required for a star of 20 M ☉ to consume all of its nuclear fuel . As an O @-@ class main sequence star , it would be 8 times the solar radius and 62 @,@ 000 times the Sun 's luminosity .
87.58284759521484 55 WikiText2
23497 = Perry the Platypus =
632.8494262695312 5 WikiText2
23498 Perry the Platypus , also known as Agent P or simply Perry , is an anthropomorphic platypus from the animated series Phineas and Ferb . Perry was created by the series ' co @-@ founders , Dan Povenmire and Jeff " Swampy " Marsh . He first appeared along with the majority of the main cast in the pilot episode " Rollercoaster . " Perry is featured as the star of the B @-@ plot for every episode of the series , alongside his nemesis Dr. Heinz Doofenshmirtz . A mostly silent character , his lone vocal characteristic ( a rattling of Perry 's beak ) was provided by Dee Bradley Baker .
45.35612106323242 117 WikiText2
23499 Perry is the pet platypus of the Flynn @-@ Fletcher family , and is perceived as mindless and domesticated . In secret , however , he lives a double life as a member of an all @-@ animal espionage organization referred to as O.W.C.A. ( The Organization Without a Cool Acronym ) . Many secret entrances to his underground lair exist all around the house ; such as the side of the house , most notably the tree that his owners sit under in the backyard , and several other everyday objects that seem to elude the family 's attention . He engages in daily battles with Dr. Heinz Doofenshmirtz , an evil scientist who desires to take over the Tri @-@ state area with obscure contraptions that work perfectly according to his intended function but fail in his application of them every time .

30.05866813659668 121 WikiText2

23450 On both apparent and absolute magnitude scales , the smaller the magnitude number , the brighter the star ; the larger the magnitude number , the fainter the star . The brightest stars , on either scale , have negative magnitude numbers . The variation in brightness ( ΔL ) between two stars is calculated by subtracting the magnitude number of the brighter star ( mb ) from the magnitude number of the fainter star ( mf ) , then using the difference as an exponent for the base number 2 @.@ 512 ; that is to say :

25.95981216430664 101 WikiText2

23451 <formula>

1999.70263671875 3 WikiText2

23452 <formula>

1999.70263671875 3 WikiText2

23453 Relative to both luminosity and distance from Earth , a star 's absolute magnitude ( M ) and apparent magnitude ( m ) are not equivalent ; for example , the bright star Sirius has an apparent magnitude of − 1 @.@ 44 , but it has an absolute magnitude of + 1 @.@ 41 .

36.28964614868164 60 WikiText2

23454 The Sun has an apparent magnitude of − 26 @.@ 7 , but its absolute magnitude is only + 4 @.@ 83 . Sirius , the brightest star in the night sky as seen from Earth , is approximately 23 times more luminous than the Sun , while Canopus , the second brightest star in the night sky with an absolute magnitude of − 5 @.@ 53 , is approximately 14 @,@ 000 times more luminous than the Sun . Despite Canopus being vastly more luminous than Sirius , however , Sirius appears brighter than Canopus . This is because Sirius is merely 8 @.@ 6 light @-@ years from the Earth , while Canopus is much farther away at a distance of 310 light @-@ years .

23.274019241333008 142 WikiText2

23455 As of 2006 , the star with the highest known absolute magnitude is LBV 1806 @-@ 20 , with a magnitude of − 14 @.@ 2 . This star is at least 5 @,@ 000 @,@ 000 times more luminous than the Sun . The least luminous stars that are currently known are located in the NGC 6397 cluster . The faintest red dwarfs in the cluster were magnitude 26 , while a 28th magnitude white dwarf was also discovered . These faint stars are so dim that their light is as bright as a birthday candle on the Moon when viewed from the Earth .

46.93743133544922 114 WikiText2

23456 = = Classification = =

856.6548461914062 5 WikiText2

23457 The current stellar classification system originated in the early 20th century , when stars were classified from A to Q based on the strength of the hydrogen line . It thought that the hydrogen line strength was a simple linear function of temperature . Rather , it was more complicated ; it strengthened with increasing temperature , it peaked near 9000 K , and then declined at greater temperatures . When the classifications were reordered by temperature , it more closely resembled the modern scheme .

39.83967590332031 86 WikiText2

23458 Stars are given a single @-@ letter classification according to their spectra , ranging from type O , which are very hot , to M , which are so cool that molecules may form in their atmospheres . The main classifications in order of decreasing surface temperature are : O , B , A , F , G , K , and M. A variety of rare spectral types are given special classifications . The most common of these are types L and T , which classify the coldest low @-@ mass stars and brown dwarfs . Each letter has 10 sub @-@ divisions , numbered from 0 to 9 , in order of decreasing temperature . However , this system breaks down at extreme high temperatures as classes O0 and O1 may not exist .

39.25697326660156 142 WikiText2

23459 In addition , stars may be classified by the luminosity effects found in their spectral lines , which correspond to their spatial size and is determined by their surface gravity . These range from 0 ( hypergiants ) through III ( giants ) to V ( main sequence dwarfs ) ; some authors add VII ( white dwarfs ) . Most stars belong to the main sequence , which consists of ordinary hydrogen @-@ burning stars . These fall along a narrow , diagonal band when graphed according to their absolute magnitude and spectral type . The Sun is a main sequence G2V yellow dwarf of intermediate temperature and ordinary size .

79.22908782958984 114 WikiText2

23460 Additional nomenclature , in the form of lower @-@ case letters added to the end of the spectral type to indicate peculiar features of the spectrum . For example , an " e " can indicate the presence of emission lines ; " m " represents unusually strong levels of metals , and " var " can mean variations in the spectral type .

50.00466537475586 66 WikiText2

23461 White dwarf stars have their own class that begins with the letter D. This is further sub @-@ divided into the classes DA , DB , DC , DO , DZ , and DQ , depending on the types of prominent lines found in the spectrum . This is followed by a numerical value that indicates the temperature .

72.82183837890625 61 WikiText2

23462 = = Variable stars = =

992.8522338867188 6 WikiText2

23463 Variable stars have periodic or random changes in luminosity because of intrinsic or extrinsic properties . Of the intrinsically variable stars , the primary types can be subdivided into three principal groups .

69.7124252319336 33 WikiText2

23464 During their stellar evolution , some stars pass through phases where they can become pulsating variables . Pulsating variable stars vary in radius and luminosity over time , expanding and contracting with periods ranging from minutes to years , depending on the size of the star . This category includes Cepheid and Cepheid @-@ like stars , and long @-@ period variables such as Mira .

51.39492416381836 70 WikiText2

23465 Eruptive variables are stars that experience sudden increases in luminosity because of flares or mass ejection events . This group includes protostars , Wolf @-@ Rayet stars , and flare stars , as well as giant and supergiant stars .

91.15422058105469 42 WikiText2

23466 Cataclysmic or explosive variable stars are those that undergo a dramatic change in their properties . This group includes novae and supernovae . A binary star system that includes a nearby white dwarf can produce certain types of these spectacular stellar explosions , including the nova and a Type 1a supernova . The explosion is created when the white dwarf accretes hydrogen from the companion star , building up mass until the hydrogen undergoes fusion . Some novae are also recurrent , having periodic outbursts of moderate amplitude .

49.07268142700195 89 WikiText2

23467 Stars can also vary in luminosity because of extrinsic factors , such as eclipsing binaries , as well as rotating stars that produce extreme starspots . A notable example of an eclipsing binary is Algol , which regularly varies in magnitude from 2 @.@ 3 to 3 @.@ 5 over a period of 2 @.@ 87 days .

44.449127197265625 64 WikiText2

23468 = = Structure = =

1031.75830078125 5 WikiText2

23469 The interior of a stable star is in a state of hydrostatic equilibrium : the forces on any small volume almost exactly counterbalance each other . The balanced forces are inward gravitational force and an outward force due to the pressure gradient within the star . The pressure gradient is established by the temperature gradient of the plasma ; the outer part of the star is cooler than the core . The temperature at the core of a main sequence or giant star is at least on the order of 107 K. The resulting temperature and pressure at the hydrogen @-@ burning core of a main sequence star are sufficient for nuclear fusion to occur and for sufficient energy to be produced to prevent further collapse of the star .

32.264991760253906 132 WikiText2

23470 As atomic nuclei are fused in the core , they emit energy in the form of gamma rays . These photons interact with the surrounding plasma , adding to the thermal energy at the core . Stars on the main sequence convert hydrogen into helium , creating a slowly but steadily increasing proportion of helium in the core . Eventually the helium content becomes predominant , and energy production ceases at the core . Instead , for stars of more than 0 @.@ 4 M ☉ , fusion occurs in a slowly expanding shell around the degenerate helium core .

42.723445892333984 102 WikiText2

23471 In addition to hydrostatic equilibrium , the interior of a stable star will also maintain an energy balance of thermal equilibrium . There is a radial temperature gradient throughout the interior that results in a flux of energy flowing toward the exterior . The outgoing flux of energy leaving any layer within the star will exactly match the incoming flux from below .

51.26933288574219 63 WikiText2

23472 The radiation zone is the region of the stellar interior where the flux of energy outward is dependent on radiative heat transfer , since convective heat transfer is inefficient in that zone . In this region the plasma will not be perturbed , and any mass motions will die out . If this is not the case , however , then the plasma becomes unstable and convection will occur , forming a convection zone . This can occur , for example , in regions where very high energy fluxes occur , such as near the core or in areas with high opacity ( making radiatative heat transfer inefficient ) as in the outer envelope .

35.801422119140625 115 WikiText2

23473 The occurrence of convection in the outer envelope of a main sequence star depends on the star 's mass . Stars with several times the mass of the Sun have a convection zone deep within the interior and a radiative zone in the outer layers . Smaller stars such as the Sun are just the opposite , with the convective zone located in the outer layers . Red dwarf stars with less than 0 @.@ 4 M ☉ are convective throughout , which prevents the accumulation of a helium core . For most stars the convective zones will also vary over time as the star ages and the constitution of the interior is modified .

33.85335159301758 117 WikiText2

23474 The photosphere is that portion of a star that is visible to an observer . This is the layer at which the plasma of the star becomes transparent to photons of light . From here , the energy generated at the core becomes free to propagate into space . It is within the photosphere that sun spots , regions of lower than average temperature , appear .

43.58253860473633 67 WikiText2

23475 Above the level of the photosphere is the stellar atmosphere . In a main sequence star such as the Sun , the lowest level of the atmosphere , just above the photosphere , is the thin chromosphere region , where spicules appear and stellar flares begin . Above this is the transition region , where the temperature rapidly increases within a distance of only 100 km ( 62 mi ) . Beyond this is the corona , a volume of super @-@ heated plasma that can extend outward to several million kilometres . The existence of a corona appears to be dependent on a convective zone in the outer layers of the star . Despite its high temperature , and the corona emits very little light , due to its low gas density . The corona region of the Sun is normally only visible during a solar eclipse .

33.98017120361328 151 WikiText2

23476 From the corona , a stellar wind of plasma particles expands outward from the star , until it interacts with the interstellar medium . For the Sun , the influence of its solar wind extends throughout a bubble @-@ shaped region called the heliosphere .

57.49843978881836 47 WikiText2

23477 = = Nuclear fusion reaction pathways = =

682.2861938476562 8 WikiText2

23478 A variety of nuclear fusion reactions take place in the cores of stars , that depend upon their mass and composition . When nuclei fuse , the mass of the fused product is less than the mass of the original parts . This lost mass is converted to electromagnetic energy , according to the mass @-@ energy equivalence relationship E = mc2 .

40.2259521484375 65 WikiText2

23479 The hydrogen fusion process is temperature @-@ sensitive , so a moderate increase in the core temperature will result in a significant increase in the fusion rate . As a result , the core temperature of main sequence stars only varies from 4 million kelvin for a small M @-@ class star to 40 million kelvin for a massive O @-@ class star .

39.00300216674805 70 WikiText2

23480 In the Sun , with a 10 @-@ million @-@ kelvin core , hydrogen fuses to form helium in the proton @-@ proton chain reaction :

143.03733825683594 32 WikiText2

23481 41H → 22H + 2e + + 2νe ( 2 x 0 @.@ 4 MeV )

397.0766906738281 18 WikiText2

23482 2e + + 2e- → 2γ ( 2 x 1 @.@ 0 MeV )

496.7121276855469 16 WikiText2

23483 21H + 22H → 23He + 2γ ( 2 x 5 @.@ 5 MeV )

376.552490234375 17 WikiText2

23484 23He → 4He + 21H ( 12 @.@ 9 MeV )

609.7614135742188 13 WikiText2

23485 These reactions result in the overall reaction :

452.8577880859375 8 WikiText2

23486 41H → 4He + 2e + + 2γ + 2νe ( 26 @.@ 7 MeV )

587.9017333984375 18 WikiText2

23487 where e + is a positron , γ is a gamma ray photon , νe is a neutrino , and H and He are isotopes of hydrogen and helium , respectively . The energy released by this reaction is in millions of electron volts , which is actually only a tiny amount of energy . However enormous numbers of these reactions occur constantly , producing all the energy necessary to sustain the star 's radiation output . In comparison , the combustion of two hydrogen gas molecules with one oxygen gas molecule releases only 5 @.@ 7 eV .

38.14534378051758 101 WikiText2

23488 In more massive stars , helium is produced in a cycle of reactions catalyzed by carbon called the carbon @-@ nitrogen @-@ oxygen cycle .

146.3300323486328 29 WikiText2

23489 In evolved stars with cores at 100 million kelvin and masses between 0 @.@ 5 and 10 M ☉ , helium can be transformed into carbon in the triple @-@ alpha process that uses the intermediate element beryllium :

151.573974609375 43 WikiText2

23490 4He + 4He + 92 keV → 8 * Be

1053.1519775390625 10 WikiText2

23491 4He + 8 * Be + 67 keV → 12 * C

990.353271484375 12 WikiText2

23492 12 * C → 12C + γ + 7 @.@ 4 MeV

666.370849609375 14 WikiText2

23493 For an overall reaction of :

666.8641357421875 6 WikiText2

23494 34He → 12C + γ + 7 @.@ 2 MeV

712.5584716796875 12 WikiText2

23495 In massive stars , heavier elements can also be burned in a contracting core through the neon burning process and oxygen burning process . The final stage in the stellar nucleosynthesis process is the silicon burning process that results in the production of the stable isotope iron @-@ 56 , an endothermic process that consumes energy , and so further energy can only be produced through gravitational collapse .

90.51050567626953 71 WikiText2

23496 The example below shows the amount of time required for a star of 20 M ☉ to consume all of its nuclear fuel . As an O @-@ class main sequence star , it would be 8 times the solar radius and 62 @,@ 000 times the Sun 's luminosity .

87.58284759521484 55 WikiText2

23497 = Perry the Platypus =

632.8494262695312 5 WikiText2

23498 Perry the Platypus , also known as Agent P or simply Perry , is an anthropomorphic platypus from the animated series Phineas and Ferb . Perry was created by the series ' co @-@ founders , Dan Povenmire and Jeff " Swampy " Marsh . He first appeared along with the majority of the main cast in the pilot episode " Rollercoaster . " Perry is featured as the star of the B @-@ plot for every episode of the series , alongside his nemesis Dr. Heinz Doofenshmirtz . A mostly silent character , his lone vocal characteristic ( a rattling of Perry 's beak ) was provided by Dee Bradley Baker .

45.35612106323242 117 WikiText2

23499 Perry is the pet platypus of the Flynn @-@ Fletcher family , and is perceived as mindless and domesticated . In secret , however , he lives a double life as a member of an all @-@ animal espionage organization referred to as O.W.C.A. ( The Organization Without a Cool Acronym ) . Many secret entrances to his underground lair exist all around the house ; such as the side of the house , most notably the tree that his owners sit under in the backyard , and several other everyday objects that seem to elude the family 's attention . He engages in daily battles with Dr. Heinz Doofenshmirtz , an evil scientist who desires to take over the Tri @-@ state area with obscure contraptions that work perfectly according to his intended function but fail in his application of them every time .