ASTR 107 Lecture Notes - Lecture 8: Planetary Nebula, Low Mass, Compact Star
Document Summary
Astr 107 lecture 8 low mass stars (cid:862)desti(cid:374)y of stars(cid:863) A low mass star is less than 8 solar masses. A brow(cid:374) dwarf"s (cid:373)ass is less tha(cid:374) . 08 solar (cid:373)asses. Thermonuclear fusion in stars with masses between . 8-8 solar masses produces radiation pressure to balance gravity for about 10 billion years. Eventually helium fuses to carbon in the core. If the conditions are right, the uv photons will ionize the gas in the expanding outer layers. Lasts for about 50,000 years before the gas expands too far and disperses. Ring nebula, m57, in lyra- in 1779 it was as large as jupiter and resembles a planet which is fading. White dwarf sirius b- mass of the sun; size o the earth, sirius a & b. Electrons are packed together as close as physically possible, electron degeneracy pressure- not normal matter. Pressure is not from moving atoms, but from the electrons. High density, compact object: one teaspoonful weights a ton.
