The Story so Far.... t = +380,000 years 1964 The Story so Far.... - PowerPoint PPT Presentation

The Story so Far.... t = +380,000 years 1964

The Story so Far.... t = +600 million years 1964 Galaxy Detected! ? udfy-38135539 z=8.6 WMAP

The Story so Far.... t = ~1 billion years 1964 Large Scale Structure ? WMAP

The Story so Far.... t = +13.73 billion years 1964 ? WMAP

The Story so Far.... t = +13.73 billion years 1964 ? • Structure? • Elements? WMAP

The Story so Far.... 1964 Structure in Early Universe: • Matter concentrated (WMAP) • Formed protogalactic clouds • Clouds collapsed & fragmented to form stars & galaxies STARS are the basic units of structure in the Universe!!

Galactic Recycling ALL HEAVY ELEMENTS ARE FORMED DEEP INSIDE STARS!

PRESSURE Star Formation: The Great Battle Between.... GRAVITY

GRAVITY (Newton’s Law of Gravity)

Thermal Pressure: PRESSURE Depends on Density and Temperature Thermal Energy: Temperature : Kinetic Energy of Measures AVERAGE Kinetic Particles Energy of Particles

The Interstellar Medium (ISM) Gas (99%) and dust (1%) in between stars Stars form in DENSE regions of the ISM.... Current Composition: 70% H, 28% He, 2% Heavy Elements

The Interstellar Medium (ISM) Gas (99%) and dust (1%) in between stars Stars form in DENSE regions of the ISM.... Early Composition: 75% H, 25% He, 0% Heavy Elements

GIANT MOLECULAR CLOUDS (GMCs) Large, Dense, & Cold regions of ISM GMCs are dense RELATIVE to ISM Made of Molecular Gas & Dust Avg. Densities: ISM: 1 atom/cc GMC: 100-1000 atoms/cc (Air: 30 billion billion molecules/cc)

GIANT MOLECULAR CLOUDS (GMCs) Large, Dense, & Cold regions of ISM GMCs are the LARGEST structures in Galaxy 0.1-10 million solar masses Why so big???

GRAVITY • Cloud Core Collapses due to GRAVITY Density Gas Particle Energies Temperature

GRAVITY FUSION!! • Stellar Nucleosynthesis, Phase 1: H-Burning • (H into He, MAIN SEQUENCE ) PRESSURE • Generates Energy & Provides Pressure!

Fusion in Stars Lighter Nuclei combine to produce Heavier Nuclei: • Only process capable of producing required energies to hold up the star against gravity! Mass of 4 H Atoms = 6.693 × 10 -27 kg Annual output of Sun = Mass of 1 He Atom = 6.645 × 10 -27 kg Annual energy used by Difference = 0.048 × 10 -27 kg Vegas every second Mass “lost” (0.7%) is converted to Energy! since the Big Bang! How much energy?

PRESSURE GRAVITY STAR IS NOW STABLE -- Hydrostatic Equilibrium -- balance between gravity & pressure

The Sun is a Mass of Incandescent Gas... Incandescence: Heat-driven light emission... ...random energies for particle collisions leads to CONTINUOUS SPECTRUM

Solar Structure - 4 (+) parts Convection zone 1. Core T~1 Million K and less 2. Radiative Zone 3. Convection Zone T=13.6 Million K 4. Photosphere Radiative zone T~2-7 Million Outer layers (Atmosphere) Photosphere+ Keep spectra in mind - Continuous, Absorption, Emission

The Sun is HOT... The Sun is a Mass of (The Sun Is So Hot That X Incandescent Gas... X Everything On It Is A Gas) core is 13,600,000 K PLASMA - ions & free electrons miasma of plasma!!

Solar Structure - CORE ...a Gigantic Nuclear Furnace (where Hydrogen Is Built Into Helium at a Temperature Of Millions Of Degrees) Energy is Generated in the CORE core is > 10,000,000 K 4 H The Proton-Proton Chain  9.2 x 10 37 reactions per He second!

Solar Structure - CORE ...a Gigantic Nuclear Furnace (where Hydrogen Is Built Into Helium at a Temperature Of Millions Of Degrees) (you don’t need to know numbers, just the idea below) Mass of 4 H Atoms = 6.693 × 10 -24 g Mass of 1 He Atom = 6.645 × 10 -24 g Difference = 0.048 × 10 -24 g Mass “lost” (0.7%) is converted to Energy!  9.2 x 10 37 reactions per second!  A little mass yields A LOT of energy: 1 gram of matter ⇒ 10 14 Joules (J) of energy E = m c 2 (powers a 100 Watt light bulb for ~32,000 years!) Sun: 90 billion Megatons TNT/second !! Albert Einstein 1905

Solar Structure - Radiative Zone ENERGY Convection zone T~1 Million K TRANSPORT BY and less RADIATION ⇒ ions & free electrons T=13.6 Million K ⇒ photons carry energy, Radiative zone interacting on the way out T~2-7 Million “RANDOM WALK” t ~ 1 million Years!

Solar Structure - Convection Zone Convection zone COOLER than T~1 Million K Radiative Zone and less ⇒ electrons bound ⇒ photons absorbed ( heat the gas) T=13.6 Million K Radiative zone ⇒ “bubbles” carry energy T~2-7 Million out

Photosphere: Visible “Surface” of the Sun MUCH COOLER Convection zone T~1 Million K and less T eff ~ 5800 K (Effective Temperature) T=13.6 Million K Radiative zone T~2-7 Million BASE: CONTINUOUS SPECTRUM

Sun is a Typical Main Sequence G Star H-R Diagram: Luminosity vs. Temperature for all stars Sun: G2 V T(surface) = 5800K (yellow) L = 3.85 x 10 26 W