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Astronomy
York University
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Michael De Robertis, Alireza Rafiee

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Class Notes

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NATS 1740 Lecture Notes - Lecture 1: Nuclear Fusion, Convection Zone, Radiation Zone

Gravitational equilibrium: gravity pulling in balances pressure pushing out. Energy balance: thermal energy released by fusion in core balances radiati

NATS 1740 Lecture Notes - Lecture 2: Fusion Power, Radiation Zone, Thermostat

Fission: big nucleus splits into smaller pieces (nuclear power plants) Fusion: small nuclei stick together to make bigger one (sun, stars) High tempera

NATS 1740 Lecture 3: 9th January 2019

*understanding goals: - the cause of solar activity. Like weather on earth (1) sunspots: they are not cold, the temperature 4000k (if you fall into in,

NATS 1740 Lecture Notes - Lecture 4: Apparent Magnitude

Have a camera to measure the luminosities, and to know how far is the star. As the star gets bigger and bigger, the star gets less energy. The further

NATS 1740 Lecture 5: 14th January 2019

Absorption lines in a star"s spectrum tell us its ionization level. Lines in a star spectrum correspond to a spectral type that reveals its temperature

NATS 1740 Lecture 6: 16th January 2019

+sun"s life expectancy: 10 billion years (until core hydrogen 10% of total is used up it burns. 10 times as much fuel, uses it 10^4 times as fast. 10 m

NATS 1740 Lecture Notes - Lecture 9: Molecular Cloud, Solar System, Flattening

Star-forming clouds: stars form in a dark clouds of dusty gas in interstellar space. + the gas between the stars is called the interstellar medium (+)

NATS 1740 Lecture Notes - Lecture 10: Brown Dwarf, Triple-Alpha Process, Main Sequence

Fusion create thermal temperature (+) brown dwarfs. A brown dwarf is hot, emits infrared light because of the internal heat left over from the contract

NATS 1740 Lecture Notes - Lecture 11: Triple-Alpha Process, Cno Cycle, Super Giant

How do high-mass stars make the elements necessary for life. How it dies: life stages of a high-mass star? (+) cno cycle. High-mass main sequence stars

NATS 1740 Lecture Notes - Lecture 12: White Dwarf, Degenerate Matter, Binary System

Very tiny in size but huge in mass. White dwarfs are the remaining cores of dead stars. Electron degeneracy pressure supports them against gravity. Whi

NATS 1740 Lecture Notes - Lecture 13: Crab Nebula, Degenerate Matter, Escape Velocity

A ball of neutron left behind from a massive star supernova. The neutrons are not stable, they can stay around millions. The degeneracy pressure of neu

NATS 1740 Lecture 14: 4th February 2019

If you drop a mass there, the mass will fall into the curve line. Techniqually, an object whose gravity is so powerful that not even light can escape i

NATS 1740 Lecture 16: 8th February 2019

Hadean period: the whole planet is extremely hot, molten. Life perhaps arose more than 3. 85 billion years ago, after the end of heavy bombardment. Fos

NATS 1740 Lecture Notes - Lecture 17: Cambrian Explosion, Tardigrade, Cyanobacteria

Microscopic, enclosed membranes or pre-cells have been created in the lab (+) chemicals to life (+) life migrated to earth. Venus, earth and mars have

NATS 1740 Lecture 23: 25th February 2019

We see a band of stars in our sky (in the milky way galaxy), appear in out sky as a faint band of light. Milky way: because ancient people has story ab

NATS 1740 Lecture Notes - Lecture 24: Galaxy Formation And Evolution, X-Ray, Event Horizon

The light of is blocked by the dust in clouds. => in the visible light, most of our view of the galaxy is blocked by opaque dust clouds. Short wavel

NATS 1740 Lecture Notes - Lecture 25: Lenticular Galaxy, Spiral Galaxy, Barred Spiral Galaxy

Hubble suggest the galaxy is 2 times bigger. Most evolutionary and precious image from the universe: hubble extreme deep field great variety of galaxie

NATS 1740 Lecture Notes - Lecture 26: Cosmic Distance Ladder, White Dwarf, Light Curve

NATS 1740 Lecture Notes - Lecture 27: Galaxy Formation And Evolution, Redshift, Cosmological Principle

NATS 1740 Lecture Notes - Lecture 28: Starburst Galaxy, Elliptical Galaxy, Spiral Galaxy

Balloon example, galaxy has no center not edge. Everything you see belongs in the past as we look back in distance. As the universe expands, the wavele