| A | B |
|---|
| Associations | Loosely bound groups of new born stars with in a nebula. |
| Brown Dwarf | Small, faint, and cool proto stars that did not become stars. |
| Evolutionary Track | The movement of a star along the H-R diagram as it evolves. |
| Protostar | The dense opaque region in the center of the stars birth. |
| Shock Wave | A rapid rush of gas going through space from stellar formation. |
| T Tauri Stars | A young Protostar on the verge of becoming a main sequence star. |
| Zero-Age Main Sequence | The time during a main sequence star when the properties stabilize. |
| Asymptotic Giant Branch | Similar to the horizontal branch this is a much fiercer burning of the red giant. |
| Black Dwarf | The cooled, burned out remnants of a main sequence star. |
| Contract Binary | If two stars overlap their Roche Lobe. |
| Core-Hydrogen Burning | Happens during the time the star is a resident of the main sequence, where hydrogen fuses to helium. |
| Electron Degeneracy Pressure | The pressure associated with the contact of tiny electrons into spheres. |
| Helium Flash | A temperature increased in a rapid runaway explosion in a red giant. |
| Horizontal Branch | The movement of an unstable red giant on the H-R diagram to a stable red giant fusing helium in the core. |
| Hydrogen-Shell Burning | When the hydrogen in the shell around the core begins to burn rapidly. |
| Main-Sequence Turnoff | Highly luminous end observed by main sequence stars. |
| Mass-Transfer Binary | When stellar mass of the stars in a binary system flows to another. |
| Planetary Nebula | The gas roughly the size of the solar system left behind from a dying main sequence star. |
| Red Supergiant | A large extremely luminous main sequence star. |
| Red-Giant Branch | Vertically up from the main sequence star where the star has cooled and expanded dramatically. |
| Roche Lobe | Tear drop shape in a binary system where the star has gravitational influence. |
| Subgiant Branch | A sub stage when a sun like star is cooling and expanding. |
| Triple-Alpha Process | The process which helium will become carbon. |
