Astronomy: Science Unit 1

Vocabulary flashcards defining key stellar concepts, stages of stellar evolution, magnitude types, and elements of the Hertzsprung-Russell Diagram.

Apparent Magnitude

The brightness of a star as seen from Earth. A lower or negative number represents a brighter star (e.g., the Sun is $-26.8$ and Sirius is $-1.46$) and a higher number represents a dim star.

Absolute Magnitude

The actual brightness of stars measured as if all stars were located at the exact same distance from Earth.

Nuclear Fusion

The core process that occurs throughout a star's life where gases fuse together, doing more than just sharing electrons, giving off light and heat at different wavelengths.

Nebula

A giant cloud of dust and gas in space from which stars are created.

Protostar

1st step in the life cycle of a star. formed from nebula, gravity, pulls gas/dust together nuclear fusion happens than light in heat are emitted

Main-Sequence Star

2nd step in the life cycle of a star. Fusion continues longest cycle of a star‘s life light and heat continued to be admitted where our Sun is now.

Red Giant

3rd step of a life cycle of a star, before the low mass and high mass stars split up. Hydrogen all used up, now helium atoms start fusing together core collapses, but atmosphere spreads out as a cooler red star

Supergiant

3rd step of a life cycle of a star, before the low mass and high mass stars split up. A massive star that forms as hydrogen depletes and burns through its fuel so quickly that it dies off relatively faster than other stars.

Supernova

Where high mass stars go after a supergiant. A giant explosion caused by the sudden collapse of a massive star because it’s hydrogen depletes

Neutron Star

A very dense, tiny ball of neutrons that remains after a high-mass star explodes in a supernova.

Pulsar

A rapidly spinning neutron star that sends out pulses of radiation.

Black Hole

The most dense object in the universe, formed when the most massive stars contract so severely that radiation and light cannot escape its massive gravity.

White Dwarf

Where low mass stars go after red giant. A hot, glowing star remnant formed after helium is completely used up and the star shrinks; white dwarfs have less mass than giants but are denser and hotter. Does not explode, instead it fades out.

Black Dwarf

The final remnant stage of a low-mass star that occurs when the light of a white dwarf eventually fades out.

Hertzsprung-Russell Diagram (HR diagram)

A scatter plot showing the relationship between a star's temperature (in Kelvin, decreasing to the right) and its luminosity or absolute magnitude.