ASTRONOMY C10 EXAM QUESTIONS WITH
DETAILED VERIFIED ANSWERS (100% CORRECT
ANSWERS) A+ GRADE ASSURED
Photosphere - correct answer-
visibleP"surface" of the sun (lowest level of the atmosphere); where the atmosphere becomes dense
Chromosphere - correct answer-sun's thinPlayer; hotter than photosphere; red due to hydrogen emission
Corona - correct answer-large, low density envelope with lots of x-rays
Solar Wind - correct answer-
electrons and positive ions streaming from the sun; interacts with planet magnetic fields and with comets
Solar Flare - correct answer-violent release of energy from the sun
Coronal Mass Ejection - correct answer-
large outburst that produces auroras in N&S longitudes on earth and can cause power outages
Prominence - correctPanswer-
more gentle eruption on sun's surface: loops of gas above chromosphere, glowing pinkish/red
Sunspots - correct answer-
black/grey b/c 2000K cooler than surroundings; can measure rotation period of the sun (about 1mo) by m
onitoring long-lived sunspots
Stars - correct answer-huge opaque luminous balls of gas held together by gravity-
400 billion in milky way only; wavelength at which spectrum peaks = measure of its surface temp
Stellar Spectrum - correct answer-
Blue: O greater than 30,000K
B 10,000-30,000
,White:
A 7,500-10,000
F 6,000-7,500
G 5,000-6,000
Red
K 3,500-5,000
M 2,200-3,500
L less than 2,200
Parallax - correct answer-distance(parsec) = 1/parallax(arc
sec) d(pc) = 1/p(arc sec)
angle subtended (covered) by 1AU (half diameter of earth's orbit); if earth to sun distance were longer an
gle would be greater and star further away
Apparent Brightness - correct answer-b = L/4πrd
energy received from a star, per unit area, per unit time
Inverse Square Law of Light - correct answer-b = L/4πd^2
luminosity and distance = proportional
Sizes of Stars - correct answer-L = 4πR^2σT^4
luminosity = (surface area)x(energy emitted/cm^2-s)
measure T from spectrum, deduce L from brightness & distance, then derive radius R
*as R changes, LPvaries*
, Mass Luminosity Relation - correct answer-L ≈ M^4
massive stars have shorter lives compared withPlow mass stars
Open Stellar Clusters - correct answer-1000 known, 20-1000 stars-
rather sparse, often many youngPstars, often in spiral arms of the galaxy
*all stars in same cluster have same distance, age and initial chemical composition
Globular Stellar Clusters - correct answer-150 known, 10^4-
10^6 stars (densely packed), all old stars, in spherical halo of the galaxy
HRPDiagram of a Cluster - correct answer-
the turn off point on the main sequence gives age of an open cluster
(see CS-163)
Evolution of a Star: Step 1 - correct answer-nebula/molecular cloud
collapse of gas and dust, pressure increases, heats up, and collapse slows down
Evolution of a Star: Step 2 - correct answer-protostar
pressure and temp. increasing, begin to radiate energy via gravitational contraction, when high temp. beco
mes high enough = nuclear reactions
Evolution of a Star: Step 3 - correct answer-brown dwarf- M<0.08 M of thePsun
if not hot enough, can't reach temp. to fuse hydrogen and helium, "failed stars", sometimes startPfusion bu
t stop
OR
main sequence star- M>0.08 M of the sun
DETAILED VERIFIED ANSWERS (100% CORRECT
ANSWERS) A+ GRADE ASSURED
Photosphere - correct answer-
visibleP"surface" of the sun (lowest level of the atmosphere); where the atmosphere becomes dense
Chromosphere - correct answer-sun's thinPlayer; hotter than photosphere; red due to hydrogen emission
Corona - correct answer-large, low density envelope with lots of x-rays
Solar Wind - correct answer-
electrons and positive ions streaming from the sun; interacts with planet magnetic fields and with comets
Solar Flare - correct answer-violent release of energy from the sun
Coronal Mass Ejection - correct answer-
large outburst that produces auroras in N&S longitudes on earth and can cause power outages
Prominence - correctPanswer-
more gentle eruption on sun's surface: loops of gas above chromosphere, glowing pinkish/red
Sunspots - correct answer-
black/grey b/c 2000K cooler than surroundings; can measure rotation period of the sun (about 1mo) by m
onitoring long-lived sunspots
Stars - correct answer-huge opaque luminous balls of gas held together by gravity-
400 billion in milky way only; wavelength at which spectrum peaks = measure of its surface temp
Stellar Spectrum - correct answer-
Blue: O greater than 30,000K
B 10,000-30,000
,White:
A 7,500-10,000
F 6,000-7,500
G 5,000-6,000
Red
K 3,500-5,000
M 2,200-3,500
L less than 2,200
Parallax - correct answer-distance(parsec) = 1/parallax(arc
sec) d(pc) = 1/p(arc sec)
angle subtended (covered) by 1AU (half diameter of earth's orbit); if earth to sun distance were longer an
gle would be greater and star further away
Apparent Brightness - correct answer-b = L/4πrd
energy received from a star, per unit area, per unit time
Inverse Square Law of Light - correct answer-b = L/4πd^2
luminosity and distance = proportional
Sizes of Stars - correct answer-L = 4πR^2σT^4
luminosity = (surface area)x(energy emitted/cm^2-s)
measure T from spectrum, deduce L from brightness & distance, then derive radius R
*as R changes, LPvaries*
, Mass Luminosity Relation - correct answer-L ≈ M^4
massive stars have shorter lives compared withPlow mass stars
Open Stellar Clusters - correct answer-1000 known, 20-1000 stars-
rather sparse, often many youngPstars, often in spiral arms of the galaxy
*all stars in same cluster have same distance, age and initial chemical composition
Globular Stellar Clusters - correct answer-150 known, 10^4-
10^6 stars (densely packed), all old stars, in spherical halo of the galaxy
HRPDiagram of a Cluster - correct answer-
the turn off point on the main sequence gives age of an open cluster
(see CS-163)
Evolution of a Star: Step 1 - correct answer-nebula/molecular cloud
collapse of gas and dust, pressure increases, heats up, and collapse slows down
Evolution of a Star: Step 2 - correct answer-protostar
pressure and temp. increasing, begin to radiate energy via gravitational contraction, when high temp. beco
mes high enough = nuclear reactions
Evolution of a Star: Step 3 - correct answer-brown dwarf- M<0.08 M of thePsun
if not hot enough, can't reach temp. to fuse hydrogen and helium, "failed stars", sometimes startPfusion bu
t stop
OR
main sequence star- M>0.08 M of the sun
