Supernovas
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  • Nearest SN candidate: Spica <br />
  • Image: http://maxim.gsfc.nasa.gov/science.html <br />

Supernovas Supernovas Presentation Transcript

  • Supernovas Yaxk'in Ú Kan Coronado IA-UNAM Coronado@astro.unam.mx
  • SUPERNOVA What is a supernova? How dangerous are they to life on Earth? How would the universe be different without supernovae?
  • Life of a Butterfly Caterpillar Eggs Pupa Butterfly 4
  • Life of a Butterfly 5
  • Life of a Sun-like Star Sun-like Star Protostars Red Giant Planetary Nebula Star-Forming Nebula White Dwarf 6
  • Life of a Massive Star Protostars Massive Star Red Supergiant Star-Forming Nebula SUPERNOVA Neutron Star Black Hole 7
  • Death of low-mass star White Dwarf White dwarfs are the remaining cores once fusion stops Electron degeneracy pressure supports them against gravity Cool and grow dimmer over time Pressure is independent of Temperature.
  • A white dwarf can accrete mass from its companion
  • Death of median-mass star Neutron star ● ● ● Compact and dense objects compose of neutrons (10¹⁷ g/cm³) Over 1.44 M sun (Chandrasekhar limit), less to 3 M sun.
  • Neutron stars and pulsars ● In 1967 Jocelyn Bell discovered very rapid pulses of radio emmision coming from a single point on the sky. – The pulses were coming from a spinning neutron star -a pulsar.
  • Pulsar at center of the Crab nebula pulses 30 times per second
  • Pulsars
  • Thought Question Could there be neutron stars that appear as pulsars to other civilizations but not to us? A. Yes B. No
  • Thought Question What happens if the neutron star has more mass than can be supported by neutron degeneracy pressure? 1.It will collapse further and become a black hole 2.It will spin even faster, and fling material out into space 3.Neutron degeneracy pressure can never be overcome by gravity
  • Neutron degeneracy pressure can no longer support a neutron star against gravity if its mass is > about 3 Msun
  • Tycho’s supernova of 1572
  • ● Supernovae outshine the whole galaxy!
  • Two kinds of supernovae Type I: White dwarf supernova White dwarf near 1.4 Msun accretes matter from red giant companion, causing supernova explosion Type II: Massive star supernova Massive star builds up 1.4 Msun core and collapses into a neutron star, gravitational PE released in explosion
  • light curve shows how luminosity changes with time
  • r process and s process elements Nuclear fusion in all stars only produces up to Fe-56 Slow neutron capture (s process) forms up to Bi-209 in low-mass stars High temps in SN creates elements up to Ca-254 Rapid neutron capture (r process) create neutron-rich isotopes which decay into more stable neutron-rich elements Neutron flux during SN is 1022 neutrons per square centimeter per second neutron captures occur much faster than decays
  • Supernovae and nucleosynthesis of elements > Fe Movie
  • Tarea ● ● ● ● Explica en cinco renglones ¿Por qué existen dos tipos de supernovas de acuerdo a las observaciones? ¿Tienen el mismo o diferente origen. Explica como se forma una SN-I A. Investiga ¿Quienes ganaron el premio nobel en 2011? y ¿Cuál es su aporte en relación a las SN-I A? ¿Por que usaron estas SN y no otras? Explica como se generan los elementos más allá del Fe en una SN.
  • Tarea Extra: ● ● Asistir la congreso nacional de astronomía, en el MUTEC del 29 de Oct. al 1° Nov. – Presentar una crónica del evento relatando tres platicas de 20 min o una plenaria – Agregar aparte una opinión de lo que aprendiste de este evento. – Describir en que consistía el poster que más te gusto.
  • Gamma Ray Burst (GRB)
  • Is radiation from supernovae and GRB sources dangerous to Earth? How close would they have to be?
  • Radiation on Earth Radioactive sources emit gamma-rays. If we are too close to a radioactive source, like a chunk of uranium, we cannot see the radiation, but it is still harmful to us! So how far should Earth be from cosmic radiation sources to be safe? 34
  • Death from Exploding Stars?! . Artist’s Conception of the Milky Way Galaxy Location of Solar System 35
  • How close would a Supernova have to be? . Location of Solar System 36
  • How close would a Supernova have to be? . Location of Solar System 37
  • How close would a Supernova have to be to be dangerous? . Supernova: within 30 light years Location of Solar System Nearest Supernova Candidate: over 250 light years away! 38
  • How close would a Gamma-Ray Burst (GRB) source have to be? . Location of Solar System 39
  • How close would a Gamma-Ray Burst (GRB) source have to be? . GRB Danger Zone: within 8,000 light years Location of Solar System 40
  • How close is the nearest Gamma-Ray Burst (GRB) source ? Nearest detected GRB source: over a Billion light years away! . Our galaxy is about 100,000 light years across GRB Danger Zone Location of Solar System 41
  • Today we know the universe is filled with powerful cosmic radiation our eyes cannot see: • Gamma-rays • X-Rays • Fast-moving atomic particles (“Cosmic Rays”) Much of which originates from monstrous black holes in the centers of galaxies and from . . . 42