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Chapters 11, 12, 13

Apparent Magnitude

the brightness of a star when viewed from Earth

Absolute Magnitude

(astronomy) the magnitude that a star would have if it were viewed from a distance of 10 parsecs (32.62 light years) from the earth

Inverse Square Law

gravitational force varies inversely with the square of the distance between two objects

Stellar Spectroscopy

the study of the properties of stars encoded in their spectra

Spectral Lines

Called the element's bright lines spectrum used to identify an element

H-R Diagram

Hertzsprung-Russell diagram, a graph that shows the relationship between a star's surface temperature and absolute magnitude


the quality of being luminous

Brown Dwarf

"Failed" star; Star not massive enough to sustain nuclear fusion.

Interstellar Medium

Gases (mainly hydrogen and helium) and dust grains (silicates, carbon and iron) filling the space in between stars. The density of interstellar mass is very low. There is about one atom of gas in every cubic centimeter of space. The density of dust is a trillion times smaller. The temperature of the gas is about 100 K.

Stellar Evolution

the changes in size, luminosity, temperature, and chemical composition that occur as a star ages

Red Dwarf

a small cool star

Supernova Remnant

An expanding shell of gas ejected at high speeds by a supernova explosion. Supernova remnants are often visible as diffuse gaseous nebulae usually with a shell-like structure. Many resemble "bubbles" in space.


a star that ejects some of its material in the form of a cloud and become more luminous in the process

Planentary Nebula

A luminous shell of gas ejected from an old, low-mass star.


a degenerate neutron star


When a high mass star tries to fuse Iron (Fe) can't because it takes more energy that it can it explodes.

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