Evolution of Single Stars. I. Stellar Evolution from Main Sequence to White Dwarf or Carbon Ignition

Model evolutionary calculations have been made for Population I stars (X=0.7, Z=0.03) with masses 0.8, 1.5, 3, 5, 7, 10 and 15 M_odot. Neutrino losses were taken into account. First the computations were made under the assumption that the stars do not lose mass. These computations were started on the main sequence and carried out through the phases of hydrogen and helium exhaustion in the center. Models of 10 and 15 M_odot ignited carbon in the center nonviolently. Stars of 3, 5 and 7 M_odot ignited carbon in the center at the density of 3x10^9 g/cm^3. This will probably lead to the type of thermonuclear supernova explosion suggested by Arnett. Also, the 1.5 M_odot model is expected to ignite carbon under similar conditions. When dynamical instability of red supergiant envelopes was taken into account, the models of 0.8, 1.5 and 3 M_odot lost their envelopes during the double shell burning phase. The masses of the remaining cores were 0.6, 0.8 and 1.2 M_odot respectively. These cores evolved through the part of the H-R diagram occupied by the nuclei of planetary nebulae, and were finally cooling down and evolving towards thewhite dwarf region.