Stars Birth lines

The B-N object may be considered to be a zero-age main sequence star that evolves with increasing surface temperature and luminosity at optical wavelengths. The descent from the right-hand upper quarter of the HR diagram, along with what has been called the Hayashi track or birth lines, precedes the entrance onto the... 

Figure 4.4 Birth Lines for stars descending onto the main sequence, where M0. denotes solar mass...

The plot of luminosity versus temperature for all stars, resulting in the main sequence, red giants and white dwarfs. Stellar evolution leads to mass - dependent birth lines onto the main sequence... 

Sketch the HR diagram and identify the four major classes of stars. A star with radius 7 x 109 m has a surface temperature of 10000 K. Plot its position on the HR diagram and indicate a birth line for this star. 

Birth lines The track of stars as they evolve from red giants onto the main sequence of the Herzprung-Russell diagram. 

Figure 3 Evolution of the central temperature and density in stars of 15M and 25M from birth as hydrogen burning stars until iron core collapse (Table 1). In general, the trajectories follow a line of p oc but with some deviation downward (towards higher p at a given T) due to the decreasing entropy of the core. Nonmonotonic behavior is observed when nuclear fuels are ignited and this is exacerbated in the 5Mq model by partial degeneracy of the gas (source Woosley et al., 2002).

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