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53 Cards in this Set
- Front
- Back
Light as a wave
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Electric and magnetic fields that travel=Electromagnetic wave
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What EM waves can human eyes detect?
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400nm-700nm
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Light as a particle (photon)
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Photon energy is proportional to 1/wavelenth
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Longer wavelength equals...
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less energy
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The electromagnetic spectrum
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Gamma ray, xray, ultraviolet, visible, infared, microwave, radio
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Two atmospheric windows
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visible, radio
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Telescopic Functions
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Light gathering Power
Resolving Power Magnifying power |
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Issac Newton
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Cut a slit in a curtain and passed the light through a prism for the colors
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Fraunhofer
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Passed light through curtain onto a diffraction grating and found dark lines. Labeled them.
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Bunsen and Kirchoff
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Passed light through heated chemicals and found bright lines. Discovered sodium on the sun
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Kirchoff's 1st Law
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If light passes through a hot, hig density solid, liquid, or gas, you get a continuous spectrum
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Kirchoff's 2nd Law
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Hot, low density gas gives off a bright line spectrum
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Kirchoff's 3rd Law
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Source of continous spectrum light passes through a cooler, low density gas creating a dark line spectrum
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Bohr
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Spectral lines are due to atomic electrons changing energy levels
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Photons are Absorbed
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dark line spectrum
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Photons are Emitted
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Bright Line Spectrum
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Balmer Series
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Electrons jumping up or down from energy level 2
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Parallax
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apparent change in an objects position due to a change in the observers location
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Parallax Method
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distance in parsecs=1/parallax angle in arc seconds
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Parallex Measurements Largest to smallest
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0.77 arc sec-0.002 arc sec
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Apparent Magnitude
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how bright a star appears to be (negative is brighter)
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Absolute Magnitude
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measure of the light output of a star
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When does (m) = (M)?
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When the distance is 10pc
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Range of M for stars
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-10 to +20
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Luminosity
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measure of the light output of a star
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Rangle of L for stars
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10 to the power of 6-10 to the power of -6
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Proper Motion
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motion perpendicular to the line of sight-moving side to side
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Radial motion
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motion along the line of sight-moving toward or away
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Doppler Effect-Moving towards
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Blue
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Moving away
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Red
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Black Body
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hot solid, liquid, or a hot, high density gas
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Black Body Radiation
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light emitted by a hot object
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Wien's Law
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temperature is proportional to 1/wavelength max
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What is Wien's law saying?
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cool stars are red, hot stars are blue
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Stefan Boltzmann Law
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L is proportional to radius squared * temperature to the fourth power
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Are stars black bodies?
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Almost, they have valleys in the dark line
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What type of spectra does a star give off?
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A dark line
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What can we find from a stars spectrum?
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Chemical Composition
Radial Motion Surface Temperature |
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Chemical composition
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by line patterns
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Radial Motion
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Shift in line patterns
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Surface Temperature
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strength of spectral lines
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Stellar Spectral Types
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OBAFGKM
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Hertzsprung-Russell Diagram
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M vs. Spectral Type
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Stellar Size
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Stefan Boltzmann law-range from 0.01R Sun-1000R Sun
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Stellar Mass
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mass a/mass b=distance b/distance a
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Newton's form of Kepler's 3rd Law
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mass a + mass b= a AU cubed/P years squared
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Range of masses
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0.08 solar masses-100 solar masses
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Stellar density range
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10 to the -6g/cm cubed-10 to the 7 g/cm cubed
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Innerstellar Medium Composition
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3/4 hydrogen, 1/4 helium, 2% heavier elements
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ISM Density
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1 atom/cm cubed
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Giant Molecular Clouds density, size, and temperature
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100 atoms/cm cubed
big cold |
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Hydrostatic Equilibrium
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balance between inward gravity and outward energy released from fusion
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How do stars form
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Shockwave goes through giant moecular cloud creating dense cores. Gravity starts to collapse these dense cores. A protostar (nucleus) forms in the dense core. Protostar gives off heat and creates energy. Hydrostatic Equilibrium occurs.
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