G-type main-sequence star: Difference between revisions
Noted that "yellow" dwarf is technically incorrect |
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[[Image:Sun920607.jpg|right|thumb|The [[Sun]], a typical example of a G V star]] |
[[Image:Sun920607.jpg|right|thumb|The [[Sun]], a typical example of a G V star]] |
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In [[astronomy]], a '''G V star''' is a [[main-sequence]] [[star]] of [[spectral classification|spectral type]] G and luminosity class V. Such a star, which can also be called a '''yellow dwarf''', is small (about 0.8 to 1.0 [[solar mass]]es) and has a [[effective temperature|surface temperature]] of between 5,300 and 6,000 [[Kelvin|K]].<ref name="hh">[http://adsabs.harvard.edu/abs/1981A&AS...46..193H Empirical bolometric corrections for the main-sequence], G. M. H. J. Habets and J. R. W. Heintze, ''Astronomy and Astrophysics Supplement'' '''46''' (November 1981), pp. 193–237.</ref><sup>, Tables VII, VIII.</sup> Like other [[main-sequence]] stars, a G V star is in the process of converting [[hydrogen]] to [[helium]] in its core by means of [[nuclear fusion]].<ref name="valpo">[http://physics.valpo.edu/courses/a101/notes/070409_LowMass.pdf Stellar Evolution: Main Sequence to Giant], class notes, Astronomy 101, [[Valparaiso University]], accessed on line [[June 19]], [[2007]].</ref> Our [[Sun]] is the most well-known (and most visible) example of a G V star. Each second, it fuses approximately 600 million [[ton]]s of [[hydrogen]] to [[helium]], converting about 4 million tons of [[matter]] to [[energy]].<ref>[http://www.astronomy.ohio-state.edu/~ryden/ast162_1/notes2.html Why Does The Sun Shine?], lecture, Barbara Ryden, Astronomy 162, [[Ohio State University]], accessed on line [[June 19]], [[2007]].</ref><ref>[http://www.ari.uni-heidelberg.de/aricns/cnspages/4c00001.htm Sun], entry at [[ARICNS]], accessed [[June 19]], [[2007]].</ref> |
In [[astronomy]], a '''G V star''' is a [[main-sequence]] [[star]] of [[spectral classification|spectral type]] G and luminosity class V. Such a star, which can also be called a '''yellow dwarf''', is small (about 0.8 to 1.0 [[solar mass]]es) and has a [[effective temperature|surface temperature]] of between 5,300 and 6,000 [[Kelvin|K]].<ref name="hh">[http://adsabs.harvard.edu/abs/1981A&AS...46..193H Empirical bolometric corrections for the main-sequence], G. M. H. J. Habets and J. R. W. Heintze, ''Astronomy and Astrophysics Supplement'' '''46''' (November 1981), pp. 193–237.</ref><sup>, Tables VII, VIII.</sup> Like other [[main-sequence]] stars, a G V star is in the process of converting [[hydrogen]] to [[helium]] in its core by means of [[nuclear fusion]].<ref name="valpo">[http://physics.valpo.edu/courses/a101/notes/070409_LowMass.pdf Stellar Evolution: Main Sequence to Giant], class notes, Astronomy 101, [[Valparaiso University]], accessed on line [[June 19]], [[2007]].</ref> Our [[Sun]] is the most well-known (and most visible) example of a G V star. Each second, it fuses approximately 600 million [[ton]]s of [[hydrogen]] to [[helium]], converting about 4 million tons of [[matter]] to [[energy]].<ref>[http://www.astronomy.ohio-state.edu/~ryden/ast162_1/notes2.html Why Does The Sun Shine?], lecture, Barbara Ryden, Astronomy 162, [[Ohio State University]], accessed on line [[June 19]], [[2007]].</ref><ref>[http://www.ari.uni-heidelberg.de/aricns/cnspages/4c00001.htm Sun], entry at [[ARICNS]], accessed [[June 19]], [[2007]].</ref> |
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Actually, the term "yellow" dwarf is actually a misnomer, as G stars actually range in color from white (early type, like the Sun) to only slightly yellow for the later types.<ref name="vend">[http://www.vendian.org/mncharity/dir3/starcolor/ What Color Are the Stars?], Mitchell N. Charity's webpage, accessed [[November 25]], [[2007]]</ref> See [[Stellar_classification#Yerkes_spectral_classification|Spectral Classification]] for a diagram of star color by spectral type. Our own Sun is in fact white. The misconception that it is yellow stems from contrast with the blue sky (which makes it appear yellow) and the reddening of the Sun close to the horizon due to [[Rayleigh Scattering]] by the atmosphere. |
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A G V star will fuse [[hydrogen]] for, very approximately, 10 billion years, until it is exhausted at the center of the star. When this happens, the star expands to many times its previous size and becomes a [[red giant]], such as [[Aldebaran]] (Alpha Tauri.)<ref>[[SIMBAD]], [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Aldebaran entry] for [[Aldebaran]], accessed on line [[June 19]], [[2007]].</ref> Eventually the red giant sheds its outer layers of gas, which become a [[planetary nebula]], while the core cools and contracts into a small, dense [[white dwarf]].<ref name="valpo" /> |
A G V star will fuse [[hydrogen]] for, very approximately, 10 billion years, until it is exhausted at the center of the star. When this happens, the star expands to many times its previous size and becomes a [[red giant]], such as [[Aldebaran]] (Alpha Tauri.)<ref>[[SIMBAD]], [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Aldebaran entry] for [[Aldebaran]], accessed on line [[June 19]], [[2007]].</ref> Eventually the red giant sheds its outer layers of gas, which become a [[planetary nebula]], while the core cools and contracts into a small, dense [[white dwarf]].<ref name="valpo" /> |
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Revision as of 22:41, 25 November 2007
In astronomy, a G V star is a main-sequence star of spectral type G and luminosity class V. Such a star, which can also be called a yellow dwarf, is small (about 0.8 to 1.0 solar masses) and has a surface temperature of between 5,300 and 6,000 K.[1], Tables VII, VIII. Like other main-sequence stars, a G V star is in the process of converting hydrogen to helium in its core by means of nuclear fusion.[2] Our Sun is the most well-known (and most visible) example of a G V star. Each second, it fuses approximately 600 million tons of hydrogen to helium, converting about 4 million tons of matter to energy.[3][4]
Actually, the term "yellow" dwarf is actually a misnomer, as G stars actually range in color from white (early type, like the Sun) to only slightly yellow for the later types.[5] See Spectral Classification for a diagram of star color by spectral type. Our own Sun is in fact white. The misconception that it is yellow stems from contrast with the blue sky (which makes it appear yellow) and the reddening of the Sun close to the horizon due to Rayleigh Scattering by the atmosphere.
A G V star will fuse hydrogen for, very approximately, 10 billion years, until it is exhausted at the center of the star. When this happens, the star expands to many times its previous size and becomes a red giant, such as Aldebaran (Alpha Tauri.)[6] Eventually the red giant sheds its outer layers of gas, which become a planetary nebula, while the core cools and contracts into a small, dense white dwarf.[2]
References
- ^ Empirical bolometric corrections for the main-sequence, G. M. H. J. Habets and J. R. W. Heintze, Astronomy and Astrophysics Supplement 46 (November 1981), pp. 193–237.
- ^ a b Stellar Evolution: Main Sequence to Giant, class notes, Astronomy 101, Valparaiso University, accessed on line June 19, 2007.
- ^ Why Does The Sun Shine?, lecture, Barbara Ryden, Astronomy 162, Ohio State University, accessed on line June 19, 2007.
- ^ Sun, entry at ARICNS, accessed June 19, 2007.
- ^ What Color Are the Stars?, Mitchell N. Charity's webpage, accessed November 25, 2007
- ^ SIMBAD, entry for Aldebaran, accessed on line June 19, 2007.
External links
- Star Types at Enchanted Learning.
See also
 | This main-sequence-star-related article is a stub. You can help Wikipedia by expanding it. |