Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
40 Cards in this Set
- Front
- Back
|
Flux |
A measure of the flow of energy out of a surface, usually applied to light |
|
|
Absolute visual magnitude |
Intrinsic brightness of a star; the apparent visual magnitude the star would have if it were 10 parsecs away |
|
|
Luminosity |
The total amount of energy a star radiates in one second |
|
|
Hertzsprung-Russell (H-R) Diagram |
A plot of intrinsic brightness vs. Surface temperature of stars |
|
|
Main sequence |
The region of the H-R diagram running from upper left to lower right |
|
|
Giant |
Large, cool, highly luminous star in the mid-to-upper right of the H-R diagram |
|
|
Supergiant |
Exceptionally luminous star whose diameter is 10 to 1,000 times greater than that of the sun |
|
|
Red dwarf |
A faint, cool, low-mass, main-sequence star |
|
|
White dwarfs |
Dying star that has collapsed to the size of Earth and is slowly sooling off; found in lower left of the H-R diagram |
|
|
Stellar parallax |
A way to measure stellar distamce by how far it shifts against the background stars |
|
|
Parsec (pc) |
The distance to a star whose parallax is one second of arc |
|
|
Luminosity classes |
Categories of stars of similar luminosity, determined by the widths of lines in their spectra |
|
|
Spectroscopic parallax |
Method of determining a star's distance by comparing its apparent magnitude with its absolute magnitude as estimated from its spectrum |
|
|
Binary stars |
Pairs of stars that orbit around their common center of mass |
|
|
Visual binary system |
A binary star system in which thr two stars are separately visible in the telescope |
|
|
Spectroscopic binary system |
A star system in which the stars are too close together to be visible separately, but we determine that there are two stars by seeing two spectra |
|
|
Eclipsing binary system |
A binary star system in which the stars eclipse each other |
|
|
Light curve |
A graph of brightness vs. Time |
|
|
Mass-luminosity relation |
The relationship which states that the more massive a main-sequence star is, the more luminous it is |
|
|
The H-R diagram is a plot of the ______ vs the ______ of stars. |
Luminosity, temperature |
|
|
You see a si gle point of light, but can detect thr spectra of two stars in a ____ binary system |
Spectroscopic |
|
|
The large size of the giants and superfiants means their spectra have sharper spectra lines and their atmospheres have _________ densities |
Low |
|
|
For main-sequence stars the greater the luminosity, the _______ the mass |
Greater |
|
|
Red dwarfs are found in the ________ part of the H-R diagram |
Lower right-hand |
|
|
White dwarfs are found in the _______ part of the H-R diagram |
Lower left-hand |
|
|
The main sequence includes roughly what percentage of all normal stars? |
90% |
|
|
The brightest luminosity class is |
Ia |
|
|
If you moved three times farther from a star, the star would appear to be how many times fainter? |
9 |
|
|
A light curve measures |
Brightness vs time |
|
|
Which best deacribes the percentage of stars that are in binary systems? |
Greater than 50% |
|
|
If you measure apparent visual magnitude and you know absolute visual magnitude, you can solve directly for the |
Distance |
|
|
A parsec is the |
The distance to a star with a parallax of one second of arc |
|
|
The most common spectral class of main-sequence stars is |
M |
|
|
The most common spectral class of main-sequence stars is |
M |
|
|
The most luminous main-sequence stars are spectral class |
O |
|
|
The most massive main-sequence stars are spectral class |
O |
|
|
A star has a parallax of 0.01 arc seconds. How far is it? |
100 parsecs |
|
|
Which star has the largest diameter? |
G2 Ib |
|
|
A star's classification is K5 III. What is the temperature of this star? |
3000 K |
|
|
A star's classification is K5 III. What type of star is this? |
Giant |
