PHYS 183 Chapter Notes - Chapter 15: Spectral Sequence, Main Sequence, Escape Velocity
Document Summary
Amount of power that is being emitted into space inverse square law for light: apparent brightness = luminosity / 4 x distance2. Highly ionized spectral lines must be fairly hot spectral lines of molecules relatively cool: spectral type: determined from spectral lines present in star"s spectrum. Hottest stars are blue, called spectral type o followed by b, a, f, g, k, When neither star eclipsed, see the combined light of both stars. When one eclipses the other, apparent brightness drops since some light blocked to measure orbital period, measure time between eclipses. Very luminous stars must be extremely large and/or have unusually high surface temperature since mass, surface temperature & luminosity are all related, we can estimate a main-sequence star"s mass by knowing the spectral type. Giants and supergiants are stars nearing the ends of their lives since have exhausted. H in core: since they have exhausted fuel, they release fusion energy at furious rate (high luminosities) & they expand.
