Formation of Stars and Planets

Stellar Formation and the Solar System

Earth and Life Science 11

Theories on the origin of the universe

• Creationist Origin

• Steady State Model

• Big Bang

Multiple Choice

[From Monday's session]

What observation did scientists use to show that the Universe is expanding?

• Red Shift

• Blue Shift

• White Shift

• Yellow Shift

Creation Stories across cultures

• Egyptians - World arose from an infinite sea when the sun first rose

• Kuba People (Africa) - Ther god felt a stomach ache and vomitted the stars sun and moon

• India - The Primal man's body parts were turned into the sky, earth, sun, and moon

• Monotheistic religions - Supreme creator

Steady State Model

• 1948, Bondi, Gould, Hoyle

• Matter is created as the universe expands

• Disproven by the discovery of the CMB

Big Bang Theory

• 13.8B years ago, big something

• Small space, High energy density towards diffuse space, Lower energy density

• E=mc²

Cosmic Evolution

The CMB

• Remnants of energy from the early universe

• Visible in the microwave spectrum

• "Relic radiation"

Multiple Choice

What mechanism allows stars to emit light and heat?

• Combustion

• Fusion

• Fission

• Oxidation

Stellar Formation

• Nebula (molecular clouds)

• Regions of a nebula can increase in density and reach a critical mass for gravitational collapse

Multiple Choice

Which of the following elements are unlikely to be found in a star?

• Hydrogen

• Lithium

• Helium

• Uranium

Multiple Choice

[True / False] The Solar System is part of the Andromeda Galaxy

• TRUE

• FALSE

Multiple Choice

[True / False] Galaxies are composed of a few hundred stars

• TRUE

• FALSE

Multiple Choice

[True / False] All the planets are equidistant from the Sun

• TRUE

• FALSE

Our Solar System

• Mass concentrated in center

• Planets orbit elliptically around the same plane

• Period of planetary revolution increases with distance

Quick Video Break

https://www.youtube.com/watch?v=KsF_hdjWJjo

Solar System Characteristics

• Most planets rotate prograde (counterclockwise)

• Inner planets are terrestrial in nature

• Outer planets are gassy

(1700's)The Nebular Hypothesis

• Self gravity contracts a gas cloud

• Conservation of angular momentum pulls cloud into a disk

• Disk rotates

• Central mass forms into proto-sun

• Centrifugal forces form rings of matter

• Rings of matter forms planets

Encounter Hypotheses

• (1749) Sun-Comet encounter deposited matter to form planets

• (1917) Sun-Star encounter draws matter from sun that formed planets

• (1904) Sun-Star encounter that drew matter from both stars that formed planets

• (1940) Sun collides with a companion star and forms proto planets

• (Accretion theory) Sun encounters a dense interstellar cloud and gets matter for planets

• (Capture theory) Sun captures a proto-star filament

(Current) Protoplanet Hypothesis

• Proto-sun forms from dust cloud

• Remaining materials from dust cloud form disks

• Collisions between dust particles and solid matter form larger bodies (proto-planets)