Henyey line

In astronomy, the Henyey line is the evolutionary path of a star in the Hertzsprung-Russell diagram from the Hayashi line to the main sequence . Along the Henyey track rise luminosity and effective temperature at. The energy transport takes place through radiation diffusion.

The rise in the effective temperature and thus the length of the Henyey line is less in low-mass stars than in high-mass stars, which spend less time on the line. Caused by the onset of nuclear fusion , the luminosity of a star drops slightly shortly before reaching the main sequence.

The line is named after the American astronomer Louis G. Henyey (1910–1970).

Development paths of young pre-main sequence stars (blue lines)

Development paths of young pre-main sequence stars:

• The development paths (blue) from the birth of a star (black line top right) to entry into the main sequence (black line bottom left) are shown.
• The end of each path is labeled with the star's mass in units of the solar mass.
• The red curves (labeled in years) are isochrones, i.e. H. Lines of constant age whose intersections with the evolutionary paths indicate the respective age of the stars.
• The nearly vertical sections are hayashi lines .
• Light stars with stay on the Hayashi Line until they reach the main sequence. ${\displaystyle \mathrm {M} /\mathrm {M} _{\odot }\lesssim 0{,}5}$
• Heavier stars turn onto the almost horizontal Henyey line. ${\displaystyle 0{,}5\lesssim \mathrm {M} /\mathrm {M} _{\odot }\lesssim 3}$
• Very heavy stars with are born directly on the Henyey line. ${\displaystyle \mathrm {M} /\mathrm {M} _{\odot }\gtrsim 3}$

Individual evidence

1. ↑ LG Henyey, L. Wilets, KH Boehm, R. Lelevier, RD Levee: A Method for Automatic Computation of Stellar Evolution. In: Astrophysical Journal . 129: 628-636 (1959).
2. ^ Steven W. Stahler: Understanding Young Stars: A History. In: Publications of the Astronomical Society of the Pacific. 100: 1474-1485 (1988).