SUPERNOVA! What is a supernova? How dangerous are they to life on Earth? How would the universe be different without supernovae? 1
Stellar Evolution: The Deaths of Stars
A hundred years ago, we believed we lived in a quiet, safe universe... 3
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... 4
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 )... neutron stars with powerful magnetic fields and more commonly from... 5
Supernova! 6
SUPERNOVAE Catastrophic explosions that end the lives of stars, Provide the heavy elements on which planets and life as we know it depends, Energize the interstellar gas to form new stars, Produce exotic compact objects, neutron stars and black holes, Provide yardsticks to measure the history and fate of the Universe.
Where does the radiation come from? 8
Life of a Butterfly Caterpillar Eggs Pupa Butterfly 9
Life of a Butterfly 10
Life of a Sun-like Star Sun-like Star Protostars Red Giant Star-Forming Nebula Planetary Nebula White Dwarf 11
Life of a Massive Star Protostars Star-Forming Nebula Massive Star Red Supergiant SUPERNOVA Neutron Star Black Hole 12
SUPERNOVA! Click on image to activate movie 13
A special effect of a stellar explosion... 14
Gamma-Ray Burst (GRB)! 15
Is radiation from supernovae and GRB sources dangerous to Earth? How close would they have to be? 16
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? 17
Death from Exploding Stars?!. Artist s Conception of the Milky Way Galaxy Location of Solar System 18
How close would a Supernova have to be?. Location of Solar System 19
How close would a Supernova have to be?. Location of Solar System 20
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! 21
How close would a Gamma-Ray Burst (GRB) source have to be?. Location of Solar System 22
How close would a Gamma-Ray Burst (GRB) source have to be?. GRB Danger Zone: within 8,000 light years Location of Solar System 23
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 24
Earth s Atmosphere & Magnetic Field Protect Earth from most high-energy radiation... But prevent us from detecting it here on Earth 25
The high view: getting a better look XMM-Newton (X-ray Multi-Mirror Mission) Suzaku Swift GLAST 26
Life from Exploding Stars! Oxygen Scientists have discovered that most of the heavy elements in the universe are dispersed from stars that go supernova. 27
Life from Exploding Stars! Silicon 28
Life from Exploding Stars! Gold 29
Life from Exploding Stars! Iron 30
Life from Exploding Stars! Without supernovae to disperse elements made in stars, there would be no planets, no life as we know it! 31
So aren t you glad we live in a universe where stars explode? Which stars? Orion s stars likely to go supernova! 32 30
33
SN 1987A Bi-polar symmetry Elongated debris
In 1987 a nearby supernova gave us a close-up look at the death of a massive star
SN 1987A SINS Kirshner, et al.
Cassiopeia A by Chandra Jet Compact remnant mass of Sun, size of Houston Counter Jet
Neutrinos emanate from supernovae like SN 1987A More than 99% of the energy from such a supernova is emitted in the form of neutrinos from the collapsing core
Recent Chandra Observatory X-ray Image of Cas A
Crab Nebula Optical Image Chandra X-Ray Image Left-over jet
Most supernovae occurring in our Galaxy are hidden from our view by interstellar dust and gases but a supernova remnant can be detected at many wavelengths for centuries after the explosion
What is a supernova? How dangerous are they to life on Earth? How would the universe be different without supernovae? 50