What Does a Sun-Like Star Eventually Become?
• Planetary nebula: He shell flashes and ejection of the star’s envelope, ionized by the star’s UV radiation; May look round (Ring Nebula or NGC 3132) but most have bipolar lobes (NGC 2346 or Henize 3-401), probably because of magnetic fields, and possibly due to orbiting companions; [The closest known in the Helix nebula, 450 ly away]. • Dying star: By this time, it has shed almost half its mass, and no more matter remains around it either, including nearby planets it may have had; Distant ones may survive, but they become warmer and ice on their moons or “Kuiper belt” objects may turn to gas. • White dwarf: From the hot remnant of the C core, cooling down; Earth-sized but with the Sun’s mass, stabilized by electron degeneracy pressure. • Examples: The first one discovered was Sirius B (small but very hot); We know other ones, but they are hard to see unless they are in binary systems… • End of evolution: The star becomes a black dwarf (unless more matter falls on it), some of its m
