ASTRONOMY LATEST
SCIENCE OLYMPIAD
MASTER EXAM
Optical double - ANSWERS-not actually binaries
simply two stars lying along same line of sight (similar RA & dec)
Not gravitationally bound
Not usefull in determining stellar masses
Visual binary - ANSWERS-both stars resolved independently
if orbital pd not too long, can monitor motion
provides angular separation from center of mass
If dist known, linear separations can be calculated
Astrometric binary - ANSWERS-If one significantly brighter, not
possible to see both directly
Exitence deduced by observing oscillatory motion of visible member
Spectrum binary - ANSWERS-two superimposed independent
discernible spectra
Doppler effect causes shifting of spectral lines
END OF
PAGE
1
, ASTRONOMY LATEST
SCIENCE OLYMPIAD
MASTER EXAM
Spectroscopic binary - ANSWERS-if period not too long
Orbital motion has component along line of sight
Periodic shift in spectral lines observable
Only 1 set of periodically varying spectral lines seen
Systems able to provide us with mass determination - ANSWERS-
Visual binaries combined with parallax info
Visual binaries with radial velocities available over complete orbit
Eclipsing double-line spectroscopic binaries
O stars - ANSWERS-Hottest blue-white stars with few lines
Strong He II absorption (sometimes emission) lines
He I absorption lines becoming stronger
B stars - ANSWERS-Hot blue-white
He I absorption lines strongest at B2
H I (Balmer) absorption lines getting stronger
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2
, ASTRONOMY LATEST
SCIENCE OLYMPIAD
MASTER EXAM
A stars - ANSWERS-White
Balmer absorption lines strongest at A), becoming weaker later
Ca II absorption lines becoming stronger
F stars - ANSWERS-Yellow-white
Ca II lines continue to increase, Balmer lines decrease
Neutral metal absorption lines (Fe I, Cr I)
G stars - ANSWERS-Yellow
Solar-type spectra
Ca II increase
Fe I, other neutral metal increase
K stars - ANSWERS-Cool orange
Ca II H & K strongest K0, then decrease
dominated by metal absorption
END OF
PAGE
3
, ASTRONOMY LATEST
SCIENCE OLYMPIAD
MASTER EXAM
M stars - ANSWERS-Cool red
Molecular absorption bands (TiO, VO)
Neutral metal absorption lines remain strong
L stars - ANSWERS-Very cool, dark red
Stronger in infrared
Strong molecular absorption bands of metal hydrides, water, CO, Na, K,
Rb, Cs, Alkalis
TiO, VO decrease
T stars - ANSWERS-Coolest, Infrared
Strong methane, CO decrease
Wolf-Rayet stars - ANSWERS-discovered by C.J.E. Wolf and G. Rayet
Paris Observatory in 1867
more than 220 WR identified, most likely more
25,000 to 100,000 K
END OF
PAGE
4
SCIENCE OLYMPIAD
MASTER EXAM
Optical double - ANSWERS-not actually binaries
simply two stars lying along same line of sight (similar RA & dec)
Not gravitationally bound
Not usefull in determining stellar masses
Visual binary - ANSWERS-both stars resolved independently
if orbital pd not too long, can monitor motion
provides angular separation from center of mass
If dist known, linear separations can be calculated
Astrometric binary - ANSWERS-If one significantly brighter, not
possible to see both directly
Exitence deduced by observing oscillatory motion of visible member
Spectrum binary - ANSWERS-two superimposed independent
discernible spectra
Doppler effect causes shifting of spectral lines
END OF
PAGE
1
, ASTRONOMY LATEST
SCIENCE OLYMPIAD
MASTER EXAM
Spectroscopic binary - ANSWERS-if period not too long
Orbital motion has component along line of sight
Periodic shift in spectral lines observable
Only 1 set of periodically varying spectral lines seen
Systems able to provide us with mass determination - ANSWERS-
Visual binaries combined with parallax info
Visual binaries with radial velocities available over complete orbit
Eclipsing double-line spectroscopic binaries
O stars - ANSWERS-Hottest blue-white stars with few lines
Strong He II absorption (sometimes emission) lines
He I absorption lines becoming stronger
B stars - ANSWERS-Hot blue-white
He I absorption lines strongest at B2
H I (Balmer) absorption lines getting stronger
END OF
PAGE
2
, ASTRONOMY LATEST
SCIENCE OLYMPIAD
MASTER EXAM
A stars - ANSWERS-White
Balmer absorption lines strongest at A), becoming weaker later
Ca II absorption lines becoming stronger
F stars - ANSWERS-Yellow-white
Ca II lines continue to increase, Balmer lines decrease
Neutral metal absorption lines (Fe I, Cr I)
G stars - ANSWERS-Yellow
Solar-type spectra
Ca II increase
Fe I, other neutral metal increase
K stars - ANSWERS-Cool orange
Ca II H & K strongest K0, then decrease
dominated by metal absorption
END OF
PAGE
3
, ASTRONOMY LATEST
SCIENCE OLYMPIAD
MASTER EXAM
M stars - ANSWERS-Cool red
Molecular absorption bands (TiO, VO)
Neutral metal absorption lines remain strong
L stars - ANSWERS-Very cool, dark red
Stronger in infrared
Strong molecular absorption bands of metal hydrides, water, CO, Na, K,
Rb, Cs, Alkalis
TiO, VO decrease
T stars - ANSWERS-Coolest, Infrared
Strong methane, CO decrease
Wolf-Rayet stars - ANSWERS-discovered by C.J.E. Wolf and G. Rayet
Paris Observatory in 1867
more than 220 WR identified, most likely more
25,000 to 100,000 K
END OF
PAGE
4
