Fundamentals of Newtonian Physics and Stellar Science

Newton

Invented calculus
Laws that govern earth Also govern the universe

Newton's First Law

A body remains at rest or moves in a straight line at a constant speed unless acted upon by an outside force.

Newton's Second Law

F = m × a

Newton's Third Law

Force from one body causes an equal and opposite reaction in the other body

Aristotelian View

Lighter objects fall slower than heavier objects

Newton's Universal Law of Gravity

Every mass attracts every other mass; attraction is directly proportional to mass and inversely proportional to the distance between their centers squared.

Gravitational Force Formula

F = G (M1 × M2) / R^2

The Bohr Model

Electrons orbit atoms in orbitals (levels)

Hydrogen Atom

Composed of 1 proton and 1 electron

Electron Transitions

Move an electron from one orbital to another; gains energy to move up, loses energy to move down.

Ionization

Electron is ejected from the atom

Photons (Light Waves)

Light emitted when electrons move between orbitals

Stefan-Boltzmann Law

Luminosity is the total energy emitted by an object each second

Blackbody

Absorbs all radiation

Blackbody Curve

Shows an object's energy output versus wavelength; peak indicates temperature and color; bluer = higher energy.

Wien's Law

Higher temperature of the object, shorter the wavelength emitted on the blackbody curve; only applies to objects that emit light.

Kirchhoff's Third Law

Light from a hot, dense object passing through cooler gas creates black lines in the spectrum.

Absorption Spectrum

Dark spectral lines within the rainbow of the spectrum, e.g., the sun.

Continuous Spectrum

No spectral lines, all rainbow.

Doppler Effect

Change in wavelength due to motion between source and observer along the line of sight.

Radial Velocity

Velocity of an object along the line of sight of an observer.

Blueshift

Shorter wavelength, moving towards the observer.

Redshift

Longer wavelength, moving away from the observer.

Stars

Self-luminous gas held by gravity, generates light through thermonuclear reactions.

What is the core of the Sun?

The source of energy and 30% of the Sun's mass.

What is the function of the Radiative Zone in the Sun?

Photons transport energy outward.

What occurs in the Convection Zone of the Sun?

Hot gas rises and dumps energy on the surface.

What is the suns visible surface?

Photosphere: Visible surface;

what is the suns chromosphere

Chromosphere: Observed using hydrogen, reddish color;

What is the sun's corona?

Corona: Visible during eclipses.

Sunspots

Cooler regions on the photosphere, discovered by Galileo.

Solar Prominences

Magnetic solar plasma loops above the surface.

Solar Flares

Release of magnetic energy, exploding charged particles.

Coronal Mass Ejections

Eruption of magnetic field in corona, particles go into space.

Magnetosphere

Earth's magnetic shield against solar particles.

Northern Lights

Charged particles interacting with Earth's magnetic field.

Apparent Magnitude (m)

Brightness observed from Earth; more negative = brighter.

Absolute Magnitude (M)

True brightness (luminosity).

Inverse Square Law

Brightness decreases with square of distance.

H-R Diagram

Temperature vs. luminosity.

Main Sequence

90% of a star's life.

Red Giants

Large but cool stars, upper-right on H-R diagram.

White Dwarfs

Small, hot, dense stars, bottom-left on H-R diagram.

Star Life Determinant

Mass affects fuel and fusion rate.

Interstellar Medium

Matter and radiation between stars.

Protostar

Early stage of a star.

Collapse Results

Heats up, rotates faster, and flattens.

Fusion Process

Hydrogen atoms fuse into helium.

Proton-Proton Chain

Fusion process in stars.

Hydrostatic Equilibrium

Balance in stars between gravity and radiation pressure.

Stellar Evolution

Star's life cycle as core fuel depletes.

Supernova Types

Type I: Star collapse due to iron core depletion; Type II: Similar collapse with more energy.

Neutron Star

Dense core of neutrons post-supernova.

Black Hole

Gravitational collapse with light unable to escape.

Who discovered solar absorption lines?

Joseph von Fraunhofer

Who recorded stellar spectra with absorption lines?

Henry Draper

Who refined spectral types by temperature?

Annie Jump Cannon

Who demonstrated that spectral lines vary with star size?

Antonia Maury

What equation did Meghnad Saha develop linking absorption lines to temperature?

Saha equation

Who proved that stars are mostly hydrogen?

Cecilia Payne-Gaposchkin