Mass Versus Radius for Zero-Age Main Sequence Stars (0.1-2.0 Msun)

Mass vs. radius for zero-age main sequence (ZAMS) stars using the PARSEC evolutionary tracks of Bressan et al. (2012; MNRAS, 427, 127) for adopted protosolar composition (helium mass fraction Y = 0.279, metals mass fraction Z = 0.017). Here, the ZAMS point was defined as the HR diagram point for each evolutionary track with minimum radius.

The ZAMS radius for a 1.00 solar mass star is 0.8709 solar radii (Rsun), corresponding to Teff = 5663K, log(L/Lsun) = -0.1532 dex at age 43.9 million years. Hence, this is the predicted radius for the Sun after it ceased its contraction to the main sequence ~4,524 million years ago and began its main sequence phase (having spent its first ~44 million years as a pre-main sequence star).