| Term |
 |
|
| Definition |
|
|
| star |
a large celestial body that is composed of gas and that emits light |
| Doppler effect |
an observed change in the frequency of a wave when the source or observer is moving |
| light-year |
the distance that light travels in one year |
| parallax |
an apparent shift in the position of an object when viewed from different locations |
| apparent magnitude |
the brightness of a star as seen from the Earth |
| absolute magnitude |
the brightness that a star would have at a distance of 32.6 light-years from Earth |
| dark-line spectra |
another name for absorption spectra |
| absorption spectra |
spectra composed of individual lines at specific frequencies characteristic of the gas |
| emmission spectra |
a spectrum consisting of a series of bright lines against a dark background |
| continuous spectra |
spectrum formed from white light contains all colors, or frequencies |
| bright-line spectra |
another name for emmission spectra |
| Sol |
the Latin name of our sun |
| hydrogen |
most-common element in stars |
| helium |
second most-common element in stars |
| apparent motion of stars |
motion visible to the unaided eye, caused by the movement of Earth |
| circumpolar stars |
stars that are always visible in the night sky |
| red-shift |
wavelength distortion caused by a star moving AWAY from Earth |
| blue-shift |
wavelength distortion caused by a star moving TOWARD Earth |
| spectrograph |
instrument used to separate light into its different colors or wavelengths |
| absorption spectra |
the kind of spectra produced by stars when observed by astronomers |
| O-blue |
class and color of hottest stars |
| M-red |
class and color of coolest stars |
| OBAFGKM |
the spectral classes, in order from hottest to coolest |
| G-yellow |
official class and color of the sun |
| circumpolar motion |
type of motion where stars appear to revolve around the North Star |
| circumpolar, constellation shift, parallax |
What are the three apparant types of stellar motion? |
| rotation, revolution (binary), and toward/away from Earth |
What are the three actual motions of stars? |
| parallax |
Scientists use this apparent motion to calculate the distance of stars that are within 1,000 light-years from Earth |
| emmission spectra |
the type of spectra we observed in the light-tubes lab |
| the gasses the star is made of |
What does a star's spectrum tell us about the star? |
Science Vocab 147928
