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star formation f
Question | Answer |
---|---|
3 basic Nebula Types | Emission(HII regions), Reflection, Dark(Bok Globules) |
Emission | Red colours due to hydrogen emission lines. Hot hydrogen gas. |
Reflection | Blue colour: starlight reflected by dust into our line of sight |
Dark (Bok Globules) | Dust cloud absorbs light in our line of sight. |
Dust clouds | 1% mass of ISM - 99% in the form of gas |
Inter Stellar Medium | Gas and dust that fills the space between stars. |
Interstellar Reddening | Stars look reddish because their blue light component has been scattered out of our line of sight by intervening dust clouds |
Schematic Dust Nebula | Diagram |
Giant Molecular Cloud (GMC) | Have complicated structures, contain complex molecular species (water, ethanol, benzene) |
Filaments, strands, and dense cores | where gas clouds are contracting under their own gravity |
Dynamical Structure | Complex gas motions (turbulence) produced by newly forming stars and supernova. They contain (HII regions) that identify active star region |
Star Formation | Stars form within low temperature molecular clouds. Key mechanism is gravitational collapse. |
Star formation formula | Large, low temperature, low density clouds + gravitational collapse + rotation = Small, high density, high temperature stars. Collapse is more rapid down the spin axis which cause a rotating disk to form around the star. Gas falls onto disk and spirals in |
Stars and Planet Formation diagram | Draw until you get it right |
Building Planets | Accretion disk and newly formed star. Planets will eventually form in the accretion disk. |
Planetary Systems | Planets grow in the accretion disks about newly formed low mass stars - the process is a natural part of star formation. We see disks about many stars. Our solar system has disk like characteristics |
Our Solar System | All planets orbit the Sun and in the same direction. They also orbit on the same plane (ecliptic plane). Planets and Sun have same age (4.5 billion years) and same chemical composition. |
Recipe for solar system | Diagram |
Planetary Types | Jovian, Terrestial |
Jovian | Large, gaseous, mostly hydrogen and helium with ice moons. In the outer solar system |
Terrestial | Small, solid 'Earth like'. In the inner solar system |
Final Growth of Terrestrial Planets | Collision of Proto-planets (sizes are close to Mars 6-7000km across where incredible amounts of energy are liberated. |
Solar Nebula Hypothesis | Division of types at boundary where ice can form. The ice line = terrestrial planets are inside of this line and Jovian planets are outside. |
Giant Impact Hypothesis Steps | 1) off centre impact by Mars sized proto-planet 2)Debris cloud forms about Earth 3)Debris begins to interact and accretion 4) Numerous small moonlets form 5) Finally one moonlet wins the accretion race and ends up being our moon 6)Timescale to form months |
Planets around other Stars | Jupiter mass planets have been found around many near-by stars like the sun. |
Doppler Shift Method | Measurement of stellar absorption lines. Period of motion of parent star caused by planet. Wobble of parent star due to large companion planet. Period of wobble = orbital period of planet. |
Doppler Shift Method diagram | diagram |
Shadow World Method | In addition to Doppler Method. Look for changes in star brightness as planet moves across its disk. |
How do hot Jupiters form | They do not. This is do to planetary migration caused by gravitational interaction with the nebula disk. |