Astro 101 Exam 2 Questions And Answers 100% Pass
Revolutions in the solar system - ✔✔✔Mostly Counterclockwise- comets can be both
Rotations in the solar system - ✔✔✔Mostly Counterclockwise. Clockwise=Venus Between=Uranus
Milky Way rotation - ✔✔✔200 km/s
Two clouds that are on adjacent circular orbits around the galaxy. What happens as they orbit? - ✔✔✔The inside cloud will eventually pass the outside one
Molecular Clouds - ✔✔✔Cool and dense-short lived-can collapse and fragment
Cloud Core - ✔✔✔Contain a protostar-small and hot
Accretion disks - ✔✔✔dense, hot, short-lived
Protostar - ✔✔✔dense, compressed interior. stable structure due to Hydrostatic Equilibrium: no more collapse when pressure matches weight of star
Hydrostatic Equilibrium - ✔✔✔Weight of material above pushes in an inward direction. gravity and pressure balance out
Solar Nebular Theory - ✔✔✔• An enormous cloud of dust and gas collapses into multiple cores. • cores starts to form a disk around a protostar. • Material in the
disk clumps. • These clumps (also called cores) draw in gas, turn into planets. • The protostar grows large enough to turn into a young star, blowing away the disk,
leaving the planets.
The temperature of the proto-Earth was about 600 K, thus the Earth formed out of: - ✔✔✔All substances that can condense at temperatures below 600 K.
The composition of the solar nebula is likely similar to: - ✔✔✔The Sun
F=ma - ✔✔✔external forces F on an object is equal to the mass m of that object multiplied by the acceleration
William Herschel - ✔✔✔Discovered- Uranus and 4 Moons, Infrared Light • Telescopes made: >400 • Symphonies written: 24
Ole Romer - ✔✔✔Ole Romer- Measured speed of light- 131,000 mpsecond
Hipparchus - ✔✔✔First comprehensive star catalog, rated stars on a six point scale of brightness--which we still use.
Apparent Magnitude - ✔✔✔- smaller numbers= brighter (m)
, Luminosity vs Brightness - ✔✔✔• Brightness is apparent—what we see. • Luminosity is energy output/second—an intrinsic (absolute) measure
Absolute luminosity+magnitude - ✔✔✔Absolute luminosity is defined as the same as apparent
Absolute magnitude (M) most negative= most luminous (brightest)
Brightness = Luminosity / distance2 • BUT! Don't use magnitudes in this equation • Use solar luminosities instead - ✔✔✔Brightness=l/d^2
Black body/thermal radiation - ✔✔✔absorbs all incident electromagnetic radiation The color of a black body is a quick measure of its temperature. • red = ~3000 K
• yellow = ~5500 K • blue = ~30,000 K
Wien's displacement law - ✔✔✔states that the black body radiation curve for different temperatures peaks at a wavelength inversely proportional to the
temperature.
Two stars same size and distance which is hotter - ✔✔✔Which peak is higher
Which of these stars in
Orion is most luminous?
star m M distance
1 Rigel 0.18 -6.69 773
2 Betelgeuse 0.42 -6.02 643
3 Bellatrix 1.64 -2.72 242
4 Alnilam 1.69 -6.38 - ✔✔✔1. Rigel- Most negative=most luminous
Two stars at the same distance, which is more
luminous? - ✔✔✔Whichever is putting out more light at all wavelengths
Two stars at the same distance, which looks redder? - ✔✔✔Which peak is in the red section 600-700nm
Two stars at the same distance, which emits more red
light? - ✔✔✔Which is higher in the red section
Which spectrum is from the
hottest object? - ✔✔✔peak furthest to the left
Kirchhoff and Bunsen - ✔✔✔Study spectral lines. spectroscope- studied emission lines- took advantage of a convenient industrial fire, and measured the amount of
sodium burning
Spectral lines - ✔✔✔show atoms have high energy levels. Blue photons=more energy than red
Revolutions in the solar system - ✔✔✔Mostly Counterclockwise- comets can be both
Rotations in the solar system - ✔✔✔Mostly Counterclockwise. Clockwise=Venus Between=Uranus
Milky Way rotation - ✔✔✔200 km/s
Two clouds that are on adjacent circular orbits around the galaxy. What happens as they orbit? - ✔✔✔The inside cloud will eventually pass the outside one
Molecular Clouds - ✔✔✔Cool and dense-short lived-can collapse and fragment
Cloud Core - ✔✔✔Contain a protostar-small and hot
Accretion disks - ✔✔✔dense, hot, short-lived
Protostar - ✔✔✔dense, compressed interior. stable structure due to Hydrostatic Equilibrium: no more collapse when pressure matches weight of star
Hydrostatic Equilibrium - ✔✔✔Weight of material above pushes in an inward direction. gravity and pressure balance out
Solar Nebular Theory - ✔✔✔• An enormous cloud of dust and gas collapses into multiple cores. • cores starts to form a disk around a protostar. • Material in the
disk clumps. • These clumps (also called cores) draw in gas, turn into planets. • The protostar grows large enough to turn into a young star, blowing away the disk,
leaving the planets.
The temperature of the proto-Earth was about 600 K, thus the Earth formed out of: - ✔✔✔All substances that can condense at temperatures below 600 K.
The composition of the solar nebula is likely similar to: - ✔✔✔The Sun
F=ma - ✔✔✔external forces F on an object is equal to the mass m of that object multiplied by the acceleration
William Herschel - ✔✔✔Discovered- Uranus and 4 Moons, Infrared Light • Telescopes made: >400 • Symphonies written: 24
Ole Romer - ✔✔✔Ole Romer- Measured speed of light- 131,000 mpsecond
Hipparchus - ✔✔✔First comprehensive star catalog, rated stars on a six point scale of brightness--which we still use.
Apparent Magnitude - ✔✔✔- smaller numbers= brighter (m)
, Luminosity vs Brightness - ✔✔✔• Brightness is apparent—what we see. • Luminosity is energy output/second—an intrinsic (absolute) measure
Absolute luminosity+magnitude - ✔✔✔Absolute luminosity is defined as the same as apparent
Absolute magnitude (M) most negative= most luminous (brightest)
Brightness = Luminosity / distance2 • BUT! Don't use magnitudes in this equation • Use solar luminosities instead - ✔✔✔Brightness=l/d^2
Black body/thermal radiation - ✔✔✔absorbs all incident electromagnetic radiation The color of a black body is a quick measure of its temperature. • red = ~3000 K
• yellow = ~5500 K • blue = ~30,000 K
Wien's displacement law - ✔✔✔states that the black body radiation curve for different temperatures peaks at a wavelength inversely proportional to the
temperature.
Two stars same size and distance which is hotter - ✔✔✔Which peak is higher
Which of these stars in
Orion is most luminous?
star m M distance
1 Rigel 0.18 -6.69 773
2 Betelgeuse 0.42 -6.02 643
3 Bellatrix 1.64 -2.72 242
4 Alnilam 1.69 -6.38 - ✔✔✔1. Rigel- Most negative=most luminous
Two stars at the same distance, which is more
luminous? - ✔✔✔Whichever is putting out more light at all wavelengths
Two stars at the same distance, which looks redder? - ✔✔✔Which peak is in the red section 600-700nm
Two stars at the same distance, which emits more red
light? - ✔✔✔Which is higher in the red section
Which spectrum is from the
hottest object? - ✔✔✔peak furthest to the left
Kirchhoff and Bunsen - ✔✔✔Study spectral lines. spectroscope- studied emission lines- took advantage of a convenient industrial fire, and measured the amount of
sodium burning
Spectral lines - ✔✔✔show atoms have high energy levels. Blue photons=more energy than red
