Presentation on theme: "Astronomy 100 Death and Black Holes (Two things you cant escape?)"— Presentation transcript:
Astronomy 100 Death and Black Holes (Two things you cant escape?)
Quiz Today! You have until 6:40 to complete 3 questions. WRITE NEATLY! PLEASE, Im begging you!
We Grow Accustomed to the Dark We grow accustomed to the Dark When light is put away As when the Neighbor holds the Lamp To witness her Goodbye A MomentWe uncertain step For newness of the night Thenfit our Vision to the Dark And meet the Roaderect And so of largerDarkness Those Evenings of the Brain When not a Moon disclose a sign Or Starcome outwithin The Bravestgrope a little And sometimes hit a Tree Directly in the Forehead But as they learn to see Either the Darkness alters Or something in the sight Adjusts itself to Midnight And Life steps almost straight. Emily Dickinson
Answer Now: What do you know about black holes? Draw me a picture of one. Goal: – Understand special types of stars and star death – Know why stellar clusters are important for learning about star life cycles Vocabulary: Mass-luminosity relationship, Helium flash, degenerate matter, Chandrasekhar limit, Lagrangian point, Roche lobes, SN II, SN Ia, SN Ib, neutrinos, neutron star, pulsar, escape velocity, singularity, Schwarzschild radius, time dilation, spaghettification, gamma ray bursts, black hole
Planck Curve (Color-Temp Relationship) There is a relationship between peak wavelength and temperature
Mass-Luminosity Relationship We also have a relationship between MASS and Luminosity 162/lect/binaries/masslum.html 162/lect/binaries/masslum.html
Things you can tell from spectra (so far) Color Composition Motion (red shift) Rotation (red shift) Temperature Luminosity Mass Color Star type (O, B, A, F, G, K, M) Star luminosity class (we didnt really go into this – but it tells you regular star, dwarf, giant, or supergiant) ?
Stellar Cluster Evolution Stars in a cluster were born at the same time They often have very similar composition So differences are because of their mass Snapshot of one age of a bunch of similar stars
Degenerate Matter – Helium Flash
Chandrasekhar Limit If what is left after a star begins to die is: Greater than 1.4 solar masses neutron star Less than 1.4 solar masses white dwarf
Life Expectancy Giant stars – burn fast – die young – 10s of millions of years Medium stars – burn – die middle-aged – 10s of billions of years Tiny stars – burn like forever – die ANCIENT – Well, the universe has only been around 14 billion years, so no white dwarfs have really died yet.
Death from the Skies
Mass is related to weight. Weight is what we call mass on EARTH Mass is how much stuff Weight is how much that stuff weighs on EARTH. I have to use mass now, but if thats confusing, say weight in your head.
Lagrangian Points!! Gravity More massive objects pull more strongly Closer objects pull more strongly
Roche Lobes What happens to the Sun as it dies? Gravity More massive objects pull more strongly Closer objects pull more strongly
Supernovae (plural of Supernova) Supernova II – What we talked about last week: – collapseexplode Supernova Ia – White dwarf gains mass, collapseexplodes – Roche lobes Supernova Ib (less important) – Regular supernova, but happens to a star with no outer layer.
Neutrinos When SN 1987a exploded we detected a huge flood of neutrinos 4 hours before we detected the light. How is that possible? Cross-section Detectors Super Kamiokande:
Neutron Star 8-20 Solar masses Smaller – generally does Sun-like collapse Bigger – ends up with a black hole
Pulsars (a special type of Neutron Star) Jocelyn Bell Burnell Highly magnetized New research: – Alice Harding – Roger Romani
Black Holes escape velocity singularity Schwarzschild radius Time dilation (relativity) Spaghettification Getting energy out of a black hole (how do we detect them then?)
WAYS TO DIE Jpg Jpg on_Death_by_Black_Hole on_Death_by_Black_Hole
Gamma Ray Bursts Gamma-ray bursts are the universe's most luminous explosions. Most occur when massive stars run out of nuclear fuel. As a star's core collapses, it creates a black hole or neutron star that, through processes not fully understood, drive powerful gas jets outward. These jets punch through the collapsing star. As the jets shoot into space, they strike gas previously shed by the star and heat it. That generates bright afterglows.stars neutron star
Sketch, Write, Answer Im doing this so that I know if Im effective as a teacher. This helps me be sure if I should review something or move on. Please answer these questions in any way you prefer. If youd like to be verbal, come chat with me quietly. – How do we detect black holes if light cannot escape? – Why cant degenerate matter heat up normally? – If 8 million billion quadrillion (a lot) of neutrinos hit you RIGHT NOW, would you feel it? Would you get cancer later in life? – What is the ONE factor that determines how a star will live its life and die?