AS102 Study Guide - Final Guide: Main Sequence, Triple-Alpha Process, Subgiant
Document Summary
Because the star can never get hot enough. Such stars, known as red dwarfs, because they are red and not very bright, consume their hydrogen very slowly and live very long lives, up to 100 billion years so it"s likely that no red dwarfs have ever died. Now we get to those stars with masses between. Just to review let"s summarize events so far: Core hydrogen gets used up so gravitational collapse commences. The star moves off main sequence becoming a subgiant and then a red giant as the outer layer begins to expand. As the core collapses it heats up sufficiently to generate a new h-he fusion furnace in the outer, hydrogen- rich layer creating outward thermal pressure resulting in expansion. The core continues to heat up, gaining he from outer-layer fusion, to high enough temperature to commence a core helium fusion reaction. The dominant product in a helium fusion furnace is carbon.
