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23 Cards in this Set

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  • Back
Stellar Spectra
Hydrogen strongest b/w A&C (Blue & Green)
Absolute visual magnitude
The "intrinsic" visual magnitude of a star; A property of the star, will not change regardless of distance.
1)distance to a star
2)apparant magnitude
hot ionized gas trapped in magnetic field lines.
Apparent Visual Magnitude
Visual magnitude of a star as it appears from Earth. Depends on...
-location of star (distance from Earth)-can change.
Apparent Visual magnitude = Absolute Visual Magnitude if the star is located 10pc away
Active regions
regions of disturbed activity.
observed in different layers.
Distance modules
The difference b/w the apparent and absolute magnitude of a star. A measure of how far away a star is.
Apparant Brightness
power/unit area perpendicular to path of light @ Earth. (l)
Stellar Temperature
Wien's Law-The hotter the star, the shorter the wavelength of peak emission.
Differential rotation drags the equatorial part of the magnetic field ahead. The sun rotates and the magn. field is dragged all the way around. Differential rotation wraps the sun in many turns of its magn. field.
Where loops of tangled magnetic field rise through the surface, sunspots occur.
Absolute Luminosity
Total power radiated by a star. (L) l=L/4(pi)(d*d)
Zeeman effect
Sunspots show a splitting of emmission lines, due to presence of a magnetic field.
Prohibits rising gas from delivering heat to surface.
Visible surface.
Low density.
Layer above photosphere.
Radiates in Hydrogen Balmer.
Temperature increases rapidly w/ height.
Apparant change is position of an object due to a change in the location of th observer. Measured in seconds of arc. Closer the star, the greater the shift.
View stars 6 months apart.
Problem: further away from sun, longer to calculate measurements.
Energy per second falling on a unit area.
Layer above the chromosphere.
Image extends out 10% distance to Earth.
Observed during solar eclipses or w/ X-Rays
The Solar Wind
Gas follows magnetic field lines.
Sometimes magn. field lines break apart, sending gas streaming outward in a solar wind.
"Coronal holes" : Source of wind
Solar flares
Magnetic field lines become too twisted, they cancel eachother out and reconnect.
Stored energy is released as photons and charged particles.
Nuclear fusion
Lighter nuclei combine to create heavier nuclei, releasing energy in the process. (in the sun) Mass in converted into energy.
Positions and # change over time.
11-yr. cycle of sunspot activity (2001-max yr)
22-yr. cycle of sunspot activity. Polarity of spots "flip" every 11 yrs., so a full cycle is 22 yrs.
Granules (size Texas).
Lasts 10-20 minutes.
Center hotter than edges, center rises, edges sink..
Convection occurs when hot fluids rise and cool fluids sinks. (ie-boiling water)
Inverse square law of light
Star twice as far as another will appear 4x as dim.
(luminosity=1/d squared)
Hydrogen fusion
(proton-proton chain)
Set of 3 reactions which convert 4 hydrogen nuclei in 1 helium nucleus. Gamma rays created, makes light.