Stars 2 Flashcards
Problem with making a census
Intrinsically faint stars are hard to see
What’s our nearest star system
Alpha Centauri
Binary stars
More than half of all stars are found in pairs or larger groups
Visual binary
A binary that can be seen through a telescope as two separate stars
Optical double
Two very close stars that are not gravitationally bound to each other
Spectroscopic binary
A binary that shows two sets of spectral lines
Eclipsing binary
A binary in which stars take turns blocking each other in our view
Binary stars orbit____ of the system
The center of mass
What is the most important property of any star
Mass
What is the typical range of mass of stars
100-250
The vast majority of stars have ____ masses
Low
What percent of stars are on the main sequence
90
What percent of stars are white dwarfs
10
What percent of stars are giants or supergiants
Less then 1
In which type of binary do we observe the Doppler shift as stars move around each other
Spectroscopic binary
Why are brown dwarfs not considered stars
They cannot fuse hydrogen to helium in their cores
Which spectral lines are prominent in O type stars
Neutral, ionized helium
What’s the suns luminosity class
V
Which molecules lines are particular to Y type brown dwarfs
Ammonia
In which type of binary does each star periodically block part or all of the other stars light
Eclipsing
What’s on the X axis of the HR diagram
Temp
What’s on the y axis of the HR diagram
Luminosity
