At the Heart of a Supernova

Your name and affiliation here

The NASA E/PO Program at Sonoma State University

• A group of eight people working collaboratively to educate the public about current and future NASA high energy astrophysics/astronomy missions.

• Led by Prof. Lynn Cominsky Swift

GLAST

XMM-Newton

What is XMM-Newton?• A joint NASA-European Space

Agency (ESA) orbiting observatory, designed to observe high-energy X-rays emitted from exotic astronomical objects such as pulsars, black holes, and active galaxies.

• XMM Newton Science Goals– When and where are the chemical

elements created?

– How does nature heat gas to X-ray emitting temperatures?

Launched in 1999!

What is GLAST?

• GLAST: Gamma-Ray Large Area Space Telescope

• Planned for launch in 2007

• GLAST has two instruments:

– Large Area Telescope (LAT)

– GLAST Burst Monitor (GBM)

• GLAST will look at many different objects within the energy range of 10keV to 300GeV.

LAT

GBM

Supernova !

Life Cycle of a Supernova

Stellar evolution made simple

Stars like the Sun go gentle into that good night

More massive stars rage, rage against the dying of the light

Puff!

Bang!

BANG!

0.077 ~8 Mo

~8 ~20 Mo

~20 ~100 Mo

Magnetic Fields Across the Universe

Magnetic Globe Demo

Neutron Stars and Pulsars

At the Heart of a Supernova

• Experiment: Using the materials provided; design and create a model of a pulsing neutron star. Describe it on the page provided.

• Suggested Materials:• Small laser lights• Diodes• Tape• Small batteries (3 V)• Modeling clay• Aluminum foil

You have 20 minutes to put your pulsar together!

Neutron Stars and Pulsars

If neutron stars are made of neutral particles, how can they have magnetic fields?

• Neutron stars are not totally made of neutrons-- the interiors have plenty of electrons, protons, and other particles.

• These charged particles can maintain the magnetic field.

• Plus, a basic property of magnetism is that once a magnetic field is made, it cannot simply disappear.

• Stars have magnetic fields because they are composed of plasma, very hot gas made of charged particles.

Crab nebula and pulsar

X-ray/Chandra

Reprise: the Life Cycle

Sun-like Stars Massive Stars

Supernova Educator Guide

Resources• XMM-Newton Education and Public

Outreach site: http://xmm.sonoma.edu

• Supernova and Magnetic Globe– http://xmm.sonoma.edu/edu/supernova

• GLAST Education and Public Outreach site: http://glast.sonoma.edu

• Downloadable GLAST materials:– http://glast.sonoma.edu/teachers/teachers.html

Additional slides

HR Diagram

Main Sequence Stars

• Stars spend most of their lives on the “main sequence” where they burn hydrogen in nuclear reactions in their cores

• Burning rate is higher for more massive stars - hence their lifetimes on the main sequence are much shorter and they are rather rare

• Red dwarf stars are the most common as they burn hydrogen slowly and live the longest

• Often called dwarfs (but not the same as White Dwarfs) because they are smaller than giants or supergiants

• Our sun is considered a G2V star. It has been on the main sequence for about 4.5 billion years, with another ~5 billion to go

How stars die• Stars that are below about 8 Mo form red giants at the

end of their lives on the main sequence• Red giants evolve into white dwarfs, often

accompanied by planetary nebulae• More massive stars form red supergiants• Red supergiants undergo supernova explosions, often

leaving behind a stellar core which is a neutron star, or perhaps a black hole

Red Giants and Supergiants

Hydrogen burns in outer shell around the core

Heavier elements burn in inner shells

Fate of high mass stars• After Helium exhausted, core collapses again

until it becomes hot enough to fuse Carbon into Magnesium or Oxygen.

12C + 12C --> 24Mg

OR 12C + 4H --> 16O

• Through a combination of processes, successively heavier elements are formed and burned.

Heavy Elements from Large Stars• Large stars also fuse Hydrogen into

Helium, and Helium into Carbon.

• But their larger masses lead to higher temperatures, which allow fusion of Carbon into Magnesium, etc.

Molecular clouds and protostars• Giant molecular clouds are

very cold, thin and wispy– they stretch out over tens of light years at temperatures from 10-100K, with a warmer core

• They are 1000s of time more dense than the local interstellar medium, and collapse further under their own gravity to form protostars at their cores

BHR 71, a star-forming cloud(image is ~1 light year across)

Protostars• Orion nebula/Trapezium stars (in the sword)• About 1500 light years away

HST/ 2.5 light years Chandra/10 light years

Stellar nurseries • Pillars of dense gas

• Newly born stars may emerge at the ends of the pillars

• About 7000 light years away

HST/EagleNebula in M16

Classifying Stars

Hertzsprung-Russell diagram

Stars spend most of their lives on the Main Sequence