A yellow dwarf or main sequence star of spectral class G is a star of spectral class G and luminosity class V. An example of a yellow dwarf is the sun . The yellow dwarfs are located roughly in the middle of the Hertzsprung-Russell diagram . The name yellow dwarf is derived from the relatively small size of these stars (compared to red giants, for example ) and their yellowish color .
Yellow dwarfs with masses of 0.8 to 1.1 solar masses have surface temperatures of around 5300 K to 6000 K. Most of the yellow dwarf stars belong to the star population I. Every second the sun fuses around 600 million tons of hydrogen to form helium , converting around 4 million tons of matter into energy .
Standard spectral stars
The revised Yerkes Atlas (Johnson & Morgan 1953) lists 11 yellow dwarf stars as the standard, with some removed from the list over time. The anchors of the MK system form the following stars:
- Asterion (G0V)
- the sun (G2V)
- Kappa1 Ceti (G5V)
- 61 Ursae Majoris (G8V)
Others add HD 115043 (G1V) and 16 Cygni B (G3V) to this list . The choice of G4V, G6V, G7V, and G9V standard stars is less clear-cut.
A yellow dwarf stays in the main sequence for about 10 billion years during its existence . It is assumed that all yellow dwarfs develop into a red giant in the further course of their existence , whereby a supernova does not occur. Eventually the red giant collapses into a white dwarf .
|Surname||Mass in M ☉||Radius in R ☉||Luminosity in L ☉|
|55 Cancri A.||0.95||0.96||0.63|
|Alpha Centauri A||1.11||1.22||1.52|
- Why Does The Sun Shine? , lecture, Barbara Ryden, Astronomy 162, Ohio State University , accessed on line June 19, 2007.
- Sun ( Memento of the original from June 16, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , entry at ARICNS, accessed June 19, 2007.
- HL Johnson & WW Morgan: Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas , 1953, Astrophysical Journal, 117, 313, bibcode : 1953ApJ ... 117..313J .
- MK ANCHOR POINTS , Robert F. Garrison
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