- G V star
In
astronomy , a G V star is amain-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 1.0solar mass es) and has a surface temperature of between 5,300 and 6,000 K. [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.] , Tables VII, VIII. Like othermain-sequence stars, a G V star is in the process of convertinghydrogen tohelium in its core by means ofnuclear fusion . [http://physics.valpo.edu/courses/a101/notes/070409_LowMass.pdf Stellar Evolution: Main Sequence to Giant] , class notes, Astronomy 101,Valparaiso University , accessed on lineJune 19 ,2007 .] OurSun is the most well-known (and most visible) example of a G V star. Each second, it fuses approximately 600 millionton s ofhydrogen tohelium , converting about 4 million tons ofmatter toenergy . [ [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 lineJune 19 ,2007 .] [ [http://www.ari.uni-heidelberg.de/aricns/cnspages/4c00001.htm Sun] , entry atARICNS , accessedJune 19 ,2007 .] Other G V stars includeAlpha Centauri A ,Tau Ceti , and51 Pegasi . [ [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Alpha+Centauri+A Alpha Centauri A] ,SIMBAD query result. Accessed on lineDecember 4 ,2007 .] [ [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Tau+Ceti Tau Ceti] ,SIMBAD query result. Accessed on lineDecember 4 ,2007 .] [ [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=51+Pegasi 51 Pegasi] ,SIMBAD query result. Accessed on lineDecember 4 ,2007 .]The term "yellow dwarf" is a misnomer, as G stars actually range in color from white, for early types like the Sun, to only slightly yellow for the later types. [http://www.vendian.org/mncharity/dir3/starcolor/ What Color Are the Stars?] , Mitchell N. Charity's webpage, accessed
November 25 ,2007 ] 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 toRayleigh 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 ared giant , such asAldebaran (Alpha Tauri.) [SIMBAD , [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Aldebaran entry] forAldebaran , accessed on lineJune 19 ,2007 .] Eventually the red giant sheds its outer layers of gas, which become aplanetary nebula , while the core cools and contracts into a small, densewhite dwarf .References
External links
* [http://www.enchantedlearning.com/subjects/astronomy/stars/startypes.shtml Star Types] at Enchanted Learning.
See also
*
Solar twin
*Red dwarf
*Brown dwarf
*K V star
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