Yellow dwarf


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Size and temperature comparison between the sun , Gliese 229 A + B , Teide 1 and Jupiter

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 .

properties

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.

development

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 .

Examples

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
Alpha Mensae 0.87 0.85 0.82
51 pegasi 1.06 1.15 1.34
18 Scorpii 1.01 1.03 1.08
Sun 1.00 1.00 1.00
Tau Ceti 0.77 0.82 0.52

Web links

Commons : Yellow dwarfs  - collection of images, videos and audio files

Individual evidence

  1. Why Does The Sun Shine? , lecture, Barbara Ryden, Astronomy 162, Ohio State University , accessed on line June 19, 2007.
  2. 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.  @1@ 2Template: Webachiv / IABot / www.ari.uni-heidelberg.de
  3. 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 .
  4. MK ANCHOR POINTS , Robert F. Garrison
  5. PC Keenan & RC McNeil: The Perkins Catalog of Revised MK Types for the Cooler Stars . In: Astrophysical Journal Supplement Series , 71 (October 1989), pp. 245-266. bibcode : 1989ApJS ... 71..245K