Presentation on theme: "At the Heart of a Supernova Sarah Silva Program Manager Sonoma State University E/PO."— Presentation transcript:
At the Heart of a Supernova Sarah Silva Program Manager Sonoma State University E/PO
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
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 and answer questions 18-27.
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.
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 M o 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. 12 C + 12 C --> 24 Mg OR 12 C + 4 H --> 16 O 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.
Resources XMM-Newton Education and Public Outreach site: http://xmm.sonoma.eduhttp://xmm.sonoma.edu Supernova and Magnetic Globe –http://xmm.sonoma.edu/edu/supernovahttp://xmm.sonoma.edu/edu/supernova GLAST Education and Public Outreach site: http://glast.sonoma.eduhttp://glast.sonoma.edu Downloadable GLAST materials for: –http://glast.sonoma.edu/teachers/teachers.htmlhttp://glast.sonoma.edu/teachers/teachers.html My Email: email@example.com
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/Eagle Nebula in M16
Classifying Stars Hertzsprung-Russell diagram Stars spend most of their lives on the Main Sequence
Pro Fusion or Con Fusion? The core of the Sun is 15 million degrees Celsius Fusion occurs 10 38 times a second Sun has 10 56 H atoms to fuse 10 18 seconds = 32 billion years 2 billion kilograms converted every second Sun’s output = 50 billion megaton bombs per second
10 18 seconds is a long time… but it’s not forever. What happens then? Don’t Let the Sun Go Down on Me
The Beginning Of The End: Red Giants After Hydrogen is exhausted in core... Energy released from nuclear fusion counter-acts inward force of gravity. Core collapses, and kinetic energy of collapse converted into heat. This heat expands the outer layers. Meanwhile, as core collapses, Increasing Temperature and Pressure...
More Fusion ! At 100 million degrees Celsius, Helium fuses: 3 ( 4 He) --> 12 C + energy (Be produced at an intermediate step) (Only 7.3 MeV produced) Energy sustains the expanded outer layers of the Red Giant
A Burst By Any Other Name… Neutron star: dense core leftover from a supernova Possess incredibly strong magnetic fields Soft Gamma Ray Repeater: violent energy release due to starquake Accretion: neutron star draws matter off binary companion Matter piles up, undergoes fusion: bang! Cycle repeats: X-Ray Burster