Chapter 10 - Slides ONLY

• Type II: Hydrogen lines in the spectrum
• Planetary Nebulae are the remnants of stars with 1 Msun to a few Msun, with radii from 0.2 to 3 light years, expanding at 10 to 20 km/s, and their phase lasts less than 10,000 years.
• Planetary Nebulae have nothing to do with planets.
• The formation of Planetary Nebulae involves a two-stage process: a slow wind from a red giant blows away cool, outer layers of the star, and a fast wind from hot, inner layers of the star overtakes the slow wind and excites it, forming a Planetary Nebula.
• White Dwarfs are degenerate stellar remnants with a C,O core, extremely dense, and a mass of 1 teaspoon of material would weigh 16 tons.
• White dwarfs have a mass of ~1 solar mass, a temperature of 25,000 K, and a luminosity of 0.01 Lsun.
• A chunk of white dwarf material the size of a beach ball would outweigh an ocean liner.
• White dwarfs are found in the lower center/left of the Herzsprung-Russell diagram due to their low luminosity and high temperature.
• The Chandrasekhar Limit states that the more massive a white dwarf, the smaller it is, until electron degeneracy pressure can no longer hold it up against gravity.
• In a binary system, each star controls a finite region of space, bounded by the Roche Lobes (or Roche surfaces).
• Lagrange points are points of stability, where matter can remain without being pulled towards one of the stars.
• Matter can flow over from one star to another through the Inner Lagrange Point, L1.
• Mass transfer in a binary system can significantly alter the stars’ masses and affect their stellar evolution.
• In a binary system consisting of a white dwarf and a main sequence or red giant star, the white dwarf accretes matter from the companion.
• Angular momentum conservation in a binary system means that the accreted matter forms a disk, called an accretion disk.
• Matter in the accretion disk heats up to ~1 million K, resulting in X-ray emission, which is an “X-ray binary”.
• The Sun may form a planetary nebula, but the outcome is uncertain.
• Type I Supernovae have no hydrogen lines in the spectrum.
• In many cases, the mass transfer cycle resumes after a nova explosion, leading to a cycle of repeating explosions every few years to decades.
• Heavy-Element Fusion in high-mass stars (> 8 MSun), leading to the formation of an inert iron core, occurs in the final stages of fusion and ends extremely rapidly, converting 2 M⊙ of Si into Fe in just ~1 day.
• Nova explosion.
• Supernovae can be seen easily in distant galaxies.
• Explosive onset of Hydrogen fusion.
• If an accreting White Dwarf exceeds the Chandrasekhar mass limit, it collapses, triggering a Type I Supernova.
• T Pyxidis is a recurrent nova.
• Iron core ultimately collapses, triggering an explosion that destroys the star: A supernova.
• The Sun’s Carbon and Oxygen core will become a White Dwarf.
• The Remnant of SN 1987A is a ring, created by stellar wind, but made to glow brightly by the X-rays released during the first hour of the Supernova explosion.
• Type I Supernovae are caused by the collapse of an accreting White Dwarf exceeding the Chandrasekhar mass limit.
• Very hot, dense layer of non-fusing hydrogen on the White Dwarf surface.
• The Sun will expand to a red giant approximately 5 billion years from now, expanding to the size of Earth’s orbit and incinerating Earth.
• Accretion disk accumulates on the surface of the White Dwarf.
• In the next decade, the expanding SN debris will reach the inner ring, causing the ring to brighten as it is obliterated by the collision.
• SN 1987A was an unusual type II Supernova in the Large Magellanic Cloud in February 1987, one of only 7 SN in all of history that were bright enough to see without a telescope.
• Eighteen hours before SN 1987A was first seen at optical wavelengths, detectors on Earth recorded 19 neutrinos arriving from the direction of the supernova, a burst that dramatically exceeded the background of low-energy sporadic neutrinos normally detected.
• Type II Supernovae are caused by the explosive onset of Hydrogen fusion.