Earth and Space: Astronomy Flashcards
What does HR stand for in the HR diagram?
Hertzsprung-Russell
What two values does the HR diagram compare?
Luminosity and temperature
A star that is very bright and hot would be found in what part of the HR diagram?
Upper left corner (main sequence)
A star that is dim and somewhat hot would be found in what part of the HR diagram?
Bottom left corner (white dwarves)
A star that is very bright and cool would be found in what part of the HR diagram?
Upper right corner (supergiants and giants)
A star that is dim and cool would be found in what part of the HR diagram?
Bottom right corner (main sequence)
Most stars are classified under what system?
Morgan-Keenan system (MK)
The Morgan-Keenan system classifies stars by letters and numbers, which are?
O, B, A, F, G, K, M (O being hottest and M being coolest).
0 - 9 (0 being hottest and 9 being coolest).
In the MK system, Roman numerals indicate what?
Luminosity
Our sun has the spectral classification of what?
G2V
Several new classifications have been added to the MK system. What are some of these?
Class L (very red dwarf), Class T (brown dwarfs with methane in their emission spectra), Class Y (brown dwarfs with ammonia in their emission spectra), Class C (carbon star).
What is found on the y-axis of the HR diagram?
Luminosity
What is found on the x-axis of the HR diagram?
Temperature
What are Kepler’s three laws of planetary motion?
- All planets move around the sun in elliptical orbits, with the sun as one of the foci.
- A radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time.
- The squares of the sidereal periods (of revolution) of the planets are directly proportional to the cubes of their mean distances from the Sun.
What is the brightest constellation?
Crux (or The Southern Cross)