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30 Cards in this Set
- Front
- Back
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Optical doubles
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stars that appear close together on the sky but are really far apart in space
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what does the lumnisoty of a star depend on?
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the distance from the apparent brightness
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spectra of the star can tell what?
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temperature which is the main perameter that determines all the features
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what does the spectra of the star usually consist on
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a series of absorbtion features
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OBAFGKM is
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temperature order from the hottest to the coolest spectral type
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spectral type O
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30,000 to 50,000K
spectral lines, ionized atoms, blue violet |
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type A
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7,500 to 11,000 spectral lines-balmer lines at maximum strenght, some ionized metals white
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type G
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5,200 to 5900 spectral lines, neutral ionizewd metals yellow
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type M
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2500 to 3900 spectral lines of neutral atoms and molecules red-orange
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Hertzsprung-russell diagram
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stars not scattered at random on lumnisoty vs. surface temp plot
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where do main sequence stars lie?
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populate a relatively narrow curved band that runs approximately diagonal in diagram
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where do supergiant and giant stars lie?
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above and to right of main sequence
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white dwarf where?
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[earth size] below and on left of main sequence
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% of the s.s are class V?most common?
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91% main sequence, M type no O's in ss
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% supergiant?
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1%
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% of stars are white dwarfs?
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9%
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what are bianary stars?
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Binary stars is the general name for gravitationally bound pairs or triplets or other systems of stars. Visual binary stars are one type of binary stars.
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visual bianary star?
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bianary stars that are widely spread so we can measure the distance
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binary stars orbit what?
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center of mass,
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kepplers 3rd law
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semi major axis in AU /and p=earth years is the euation of the two masses. if center of mass can be determined so can relative size
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mass of a star determines
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the lumnosity of a main sequence. high mass=high lumnosity
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a lifetime of a star decreases as
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mass increases
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closely spaced stars reveal themselves by the
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doppler shift
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when do double line spectroscopic bianaries occur
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when lines from both stars in a bianary system are observed
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where must u bee to see a eclipsing bianary
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90 degree edge on earth
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when an eclipsing bianary star is also a double it is possible to solve for
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mass, diameter, brightness, speed of orbit and sepertation
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stellar evolution of main streem stars
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hydrogen burns into helieum
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when will the helieum flash occur
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when stars are less than 2 solar masses
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Asymptotic gain branch
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shell helium burning with an intermittent shell of hydrogen burning
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What happens at the end of the AGB phase
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the helium shell burning comes unstable and goes into a series of helium flashes
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