Stars I
A luminous sphere of gas that undergoes nuclear fusion
Star Colour
Red = cooler
Blue = hotter
Proto Star
A star that has not condensed enough yet to start nuclear fusion
Black Dwarf
Cold remains of a white dwarf star core
Protoplanetary disk
Disk of spinning gas and dust leftover from a collapsing nebula that has NOT become part of a star
Moon
A natural satellite that orbits a planet
Nuclear Fusion
When two smaller elements collide and fuse together to make a larger element, this releases energy
1Msun
One mass of the Sun - a star the same size as the Sun
Red Dwarf
Small main sequence star that is cool and only fuses Hydrogen
Nebula
Cloud of gas and dust that collapses inwards creating a protostar in the centre
Frost Line
Temperature line inside of which it is too warm for ice to stay frozen, outside of which water can freeze into solid ice.
Capture
An asteroid that got too close to the gravitational field of a planet and got caught in orbit
Gas Pressure
Outward force that expands a star caused by heat from the core
Relative Magnitude
How bright a star appears from Earth due to how far away it is AND its luminosity
Brown Dwarf
A proto star that never got big enough to do sustained nuclear fusion
Main Sequence
Stars that are fusing Hydrogen into Helium in their cores these can be a range of different sizes and colours
Terrestrial Planets
Small, made of rock and metal only, form inside the frost line.
Collision
When two planets collide one gets ripped apart and turned into a trail of debris that gets caught in orbit around the other planet and accretes into a spherical large moon
Gravity
Inward force that makes a star smaller and more dense
Absolute Magnitude
How bright a star really is, how bright it would appear from a set distance away from Earth
White Dwarf
Dead core of a small to medium sized star that has run out of fuel and can no longer do nuclear fusion it is luminous due to remnant heat only
Supernova
When a large star fuses heavier elements all the way up to iron in its core then can no longer sustain nuclear fusion it explodes into a supernova
Gas Giants
Large planets made of rock/ice/gas that form outside the frost line - bigger due to more solid stuff that can accrete
Accretion
Moons that form from circumplanetary disks of dust around a gas giant planet, this dust accretes into a spherical moon that orbits close to the planet
Hydrostatic Equilibrium
When gas pressure outwards and gravity inwards are balanced so a star does not get any bigger or smaller
Luminosity
Energy emitted by the surface of a star every second
Red Giant
A sun sized star that has run out of Hydrogen fuel, collapsed, then started to fuse Helium causing outer layers to expand again
Neutron Star
Leftover core of a very large star after it has undergone supernova
Differentiation
When a protoplanet separates out into more and less dense layers eg. metal sinks to core, less dense rock rises to surface of a terrestrial planet
Circumplanetary Disk
Disk of dust and leftover material around a gas giant planet that did not accrete this can become a moon