Spectra as the window on stars Flashcards
Spectra as key to stars
Spectra are the patterns of absorption or emission lines we see
in stars and are very useful
Temperature
The different patterns primarily tell us about the accurate
temperature of a star.
Composition
Once we know the temperature we can work out the composition
as we know how strong the spectral lines from each element
should be
Binary stars
The Doppler effect, shifting of lines was proof that binary stars
exist. Two stars gravitationally bound to orbit around each other
Apparent binaries:
tars seen close together in the sky but not physically connected
Visual binaries
Stars seen close together in the sky and ARE physically connected
as we can see their orbit.
Astrometric binaries:
where we can only see one star but we can see it is orbiting
another object to faint to see
Spectroscopic binaries
Stars seen as one but are physically connected. Only
detected because of the velocity of one or both stars is seen to change.Most times
only one spectrum is observed
Eclipsing binaries:
Seen as one in the sky but rotate about a common centre. Only
detected because each star in turn partially blocks the light from the other
Photometric binaries:
binaries that do not eclipse but we can still infer they are in a
binary due to their magnitude of colour variations over time.
