Presentation on theme: "Quick introduction: Supernova ! Visible supernovae are uncommon and of great interest to astronomers. They occur when a massive star has burned up most."— Presentation transcript:
Quick introduction: Supernova ! Visible supernovae are uncommon and of great interest to astronomers. They occur when a massive star has burned up most of its “fuel” and suddenly “collapses”. A shock wave is formed which blows off the outer layers of the star. Supernovae in our own galaxy had not been seen since the 1600’s until ………………………… 1987
One dramatic result of stellar evolution: a supernova remnant
Hydrostatic equilibrium maintains a star’s size during Stage 7
Stellar composition changes as the hydrogen is used up During stage 7 of stellar evolution, hydrogen burning causes a build-up of helium in the star’s core.
Hydrogen shell burning occurs around an “ash” core, which is mostly helium, and the temperature is T = 10 million K
Helium shell burning continues, and carbon burning commences
A Type II Supernova is a “core collapse” and occurs when the core is finally pure iron, which cannot be fused to other elements. The core collapses to a big ball of neutrons, which causes a shock wave to bounce back outward, which blows off the entire envelope of the red giant, to form a supernova remnant.
Supernovae in our galaxy have been infrequent. Historical supernovae in the Milky Way (none observed by telescope !!!!): http://www.seds.org/messier/more/mw_sn.htmlhttp://www.seds.org/messier/more/mw_sn.html Recent supernovae by date: http://cfa- www.harvard.edu/iau/lists/RecentSupernovae.htmlhttp://cfa- www.harvard.edu/iau/lists/RecentSupernovae.html All supernovae since 1885: http://cfa- www.harvard.edu/iau/lists/Supernovae.htmlhttp://cfa- www.harvard.edu/iau/lists/Supernovae.html Links for supernovae on the web: http://rsd- www.nrl.navy.mil/7212/montes/sne.htmlhttp://rsd- www.nrl.navy.mil/7212/montes/sne.html Latest supernovae (by current brightness !): http://www.rochesterastronomy.org/supernova.html http://www.rochesterastronomy.org/supernova.html Supernova SN2005cs in M51 (Whirlpool galaxy): http://www.rochesterastronomy.org/sn2005/sn2005cs.html also see: http://antwrp.gsfc.nasa.gov/apod/ap050719.html http://www.rochesterastronomy.org/sn2005/sn2005cs.htmlhttp://antwrp.gsfc.nasa.gov/apod/ap050719.html
Supernova Remnants Vela supernova remnant Other examples: Cassiopeia A (link) (link)link N63A (link)link Crab nebula
M1 – the Crab Nebula is from a supernova seen in year A.D. 1054 The remnant is 1800 pc away and the diameter is currently 2 pc.
Astronomers have been waiting for hundreds of years for a bright, nearby supernova. Finally, one night in 1987… We learn the story of the observation in the movie “Death of a Star” (from the Nova series on PBS)