Learning Goals: 4. Complex Knowledge: demonstrations of learning that go aboveand above and beyond what was explicitly taught. 3. Knowledge: meeting the learning goals and expectations. 2. Foundational knowledge: simpler procedures, isolated details, vocabulary. 1. Limited knowledge: know very little details but working toward a higher level. How do stars differ from moons and planets, and from one another? How does the classification of stars help us understand how they evolve over their lifetimes? What are the different types of stars? What happens when different types of stars die? Why is it important for us to understand stars?

What is a planetary nebula and how is it formed? Bell Work 3-14-16 What is a planetary nebula and how is it formed?

Supernovae

M1 – the Crab Nebula – SN1054

2 Types (there are actually like 7 or 8, but we are pretending there are 2) Type 1a Only in Binary Stars One of which has to be a white dwarf Other has to be a red (super)giant Pretty specific setup Not common Type 2 This is what you have heard of before How massive stars die Much more common

Type Ia supernovae Type 1a: These result from some binary star systems in which a carbon-oxygen white dwarf is accreting matter from a companion. so much mass piles up on the white dwarf that its core reaches a critical mass (1.4 solar masses, Chandrasekhar limit) which is enough to result in an uncontrolled fusion of carbon and oxygen, thus detonating the star. Because they ALWAYS happen when the white dwarf gets to 1.4 solar masses, they are ALWAYS the same brightness. When we see them we can tell exactly how far away they are We can use these as galactic measuring sticks as well! Nothing is left over…

Type Ia supernovae

https://www.youtube.com/watch?v=5YZkAo R3WLE

Type II supernovae 95% of stars become white dwarfs 5% explode in Type II supernovae

Type II Supernova Starts with a red supergiant star that is at least 8 times more massive than our sun. (Chandrasekhar Limit) When the star’s internal furnace can no longer sustain nuclear fusion its core collapses under gravity in a fraction of a second It is going a significant fraction of the speed of light! A rebound shockwave from the implosion rushes upward through the star’s layers. Only 60 minutes later the full fury of the shockwave reaches the surface and the doomed star blasts apart as a supernova explosion.

Within a massive, evolved star (a) the onion-layered shells of elements undergo fusion, forming an iron core (b) that reaches Chandrasekhar-mass and starts to collapse. The inner part of the core is compressed into neutrons (c), causing infalling material to bounce (d) and form an outward-propagating shock front (red). The shock starts to stall (e), but it is re-invigorated by a process that may include neutrino interaction. The surrounding material is blasted away (f), leaving only a degenerate remnant.

https://www.youtube.com/watch?v=N5oEVw7lJ1E

https://www.youtube.com/watch?v=kLlILnQj Gfc The brilliant flash of an exploding star’s shockwave—what astronomers call the “shock breakout” -- is illustrated in this cartoon animation. The animation begins with a view of a red supergiant star that is 500 times bigger and 20,000 brighter than our sun. When the star’s internal furnace can no longer sustain nuclear fusion its core to collapses under gravity. A shockwave from the implosion rushes upward through the star’s layers. The shockwave initially breaks through the star’s visible surface as a series of finger-like plasma jets. Only 20 minute later the full fury of the shockwave reaches the surface and the doomed star blasts apart as a supernova explosion. This animation is based on photometric observations made by NASA’s Kepler space telescope. By closely monitoring the star KSN 2011d, located 1.2 billion light-years away, Kepler caught the onset of the early flash and subsequent explosion.

SN 1054 SN 1054 is a supernova that was first observed as a new "star" in the sky on July 4, 1054 AD. lasted for a period of around two years. was recorded in multiple Chinese and Japanese documents and in one document from the Arab world. it has been hypothesized that it was also observed by American-Indian tribes and Europeans, it has not been conclusively proven.

M1 – the Crab Nebula – SN1054

Supernova Candidates Several large stars within the Milky Way have been suggested as possible Type II supernovae within the next million years. Eta Carinae RS Ophiuchi U Scorpii VY Canis Majoris Betelgeuse Antares Spica. UY Scuti The nearest supernova candidate is IK Pegasi (HR 8210), located at a distance of 150 light-years. The binary star system consists of a main sequence star and a white dwarf 31 million kilometers apart. The dwarf has an estimated mass 1.15 times that of the Sun. Within several million years the white dwarf could accrete the critical mass required to become a Type Ia supernova.

A really smart guy explaining the difference between type 1a and type 2 https://www.youtube.com/watch?v=6bNyasANvqU

What is left over??? Supernovas occur when the stars have a mass > 8-10 solar masses. (Chandrasekhar Limit) The explosion can have 3 results: Nothing left. Neutron Stars Black Holes

Nothing left

Neutron Stars Supernova remnants formed by the in-falling matter from the supernova explosion and a rebound of the core (bigger than white dwarf, smaller than black hole) almost incomprehensible density causes protons and electrons to combine into neutrons neutron stars rotate in space as they form. When they compress and shrink, this spinning speeds up due to the conservation of angular momentum Pulsars – 4.3 seconds per rotation – 642rotations per second Very stable. Almost like a space clock!

https://www.youtube.com/watch?v=ZW3aV7 U-aik