| A | B |
|---|
| Absolute Brightness | This is the luminosity no matter where an observer is located. |
| Absolute Magnitude | Is the brightness of a star if it were to be viewed from 10pc away. |
| Apparent Brightness | The amount of energy striking a unit area of some light sensitive surface or device per unit time. |
| Apparent Magnitude | System set for magnitude on Earth to measure brightness. |
| Binary-star Systems | Two stars with in a system orbiting around a center point. |
| Blue Giants | Large stars at the top end of the main sequence, blue in color. |
| Blue Supergiants | Stars with a size 1000 times larger than the sun and blue in color. |
| Color Index | The ratio of its Blue to Visual intensities. |
| Color Magnitude Diagrams | Plot of stars luminosity by its absolute magnitude. |
| Dwarf | A star that’s radius is comparable or smaller to our suns. |
| Eclipsing Binaries | The orbit plane of the pair of stars is almost edge-on to our line of sight. |
| Giants | Stars that have a radius that is 10 to 100 times larger than our sun. |
| Globular Cluster | Tightly bound, roughly spherical collection of hundreds f thousands, and sometimes millions, of stars spanning about 50 pc. Globular clusters are distributed in the halos around the Milky Way and other galaxies. |
| H-R Diagram | A plot of luminosity verses temperature for well known stars. |
| Light Curve | The variations of stars brightness of a star over time. |
| Magnitude Scale | Brightness of stars based on the Greek system set down by Hipparchus. |
| Main Sequence | The major band found in the H-R diagram. |
| Open Cluster | Loosely bound collection of tens to hundreds of stars, a few parsecs across, generally found in the plane of the Milky Way. |
| Parallax | To measure distance to terrestrial and solar system objects. |
| Parsec | “Parallax in arc seconds” a distance used to measure how far away stars are from Earth or the solar system, about 3.3 light years. |
| Photometry | “Light measurement” a non spectral line analysis, measured with standard filters. |
| Proper Motion | The movement of other stars transverse and radial motion. |
| Radius-Luminosity-Temperature Relationship | The equation used to calculate the size and temperature of a distant star. |
| Red Dwarfs | Small cool stars located at the bottom end of main sequence stars. |
| Red Giant Region | Large stars in the upper right hand corner of the H-R diagram. |
| Red Giant | A star with a temperature of 3000K and red in color. |
| Spectral Classes | Classification scheme, based on the strength of the stellar spectral lines, which indicated the temperature of the star. |
| Spectroscopic Binaries | The binary components can not be resolved into two different stars. |
| Star Cluster | A group of stars orbiting a common point. |
| Supergiants | Stars that have a radius that is 1000 times the solar radii. |
| Visual Binaries | Binary systems which space is easily seen. |
| White Dwarf Region | A type stars at the bottom left hand side of the H-R diagram. |
| White Dwarf | A star smaller or comparable to that of our suns, but has a temperature of 24,000K. |
