Fig8_7 Convection inside stars of different mass

Fig8_7 Convection inside stars of different mass

Fig. 8.7 . Most stars have convective zones in which energy is transported by the wheeling motion of convection, denoted here by closed curves with arrows for stars of different mass, designated by M and compared to the Sunís mass designated M-. The symbol < means less than, and > denotes greater than. Low-mass stars, with less than half a solar mass, are fully convective from core to visible disk and thus of uniform composition. Their low temperatures result in a high opacity to radiation. In intermediate-mass stars, such as the Sun, radiation transport dominates convection in the hot central regions, which are enveloped by a cooler convective region. The visible disks of these stars do not include the nuclear fusion products from their core, but retain the same composition as the interstellar medium from which these stars formed. High-mass stars, with more than 1.5 times the mass of the Sun, have a large radiative zone that is not enveloped by a convective zone. The temperature-sensitive hydrogen burning reactions of the CNO cycle causes the development of a convective core in these stars.

Copyright 2010, Professor Kenneth R. Lang, Tufts University