AST-220 EXAM QUESTIONS WITH
ANSWERS 100% CORRECT
absolute magnitude - ANSWER The apparent magnitude a star would have if it were
placed at a standard distance of 10 parsecs from Earth.
absorption line - ANSWER Dark line in an otherwise continuous bright spectrum, where
light within one narrow frequency range has been removed.
active Sun - ANSWER The unpredictable aspects of the Sun's behavior, such as sudden
explosive outbursts of radiation in the form of prominences and flares.
apparent magnitude - ANSWER The apparent brightness of a star, expressed using the
magnitude scale.
blue giant - ANSWER Large, hot, bright star at the upper-left end of the main sequence
on the Hertzsprung-Russell diagram. Its name comes from its color and size.
chromosphere - ANSWER The Sun's lower atmosphere, lying just above the visible
atmosphere.
convection cell - ANSWER Circulating region of upwelling hot fluid and sinking cooler
fluid in convective motion.
convection zone - ANSWER Region of the Sun's interior, lying just below the surface,
where the material of the Sun is in constant convection motion. This region extends into
the solar interior to a depth of about 20,000 km.
core (of the Sun) - ANSWER The central region of the Sun where nuclear reactions
produce the Sun's energy.
corona - ANSWER One of numerous, large, roughly circular regions on the surface of
Venus, though to have been caused by upwelling mantle material causing the planet's
crust to bulge outward.
coronal hole - ANSWER Vast regions of the Sun's atmosphere where the density of
matter is about 10 times lower than average. The gas there streams freely into space at
high speeds, escaping the Sun completely.
coronal mass ejection - ANSWER Giant magnetic "bubble" of ionized gas that separates
from the rest of the solar atmosphere and escapes into interplanetary space.
Doppler effect - ANSWER Any motion-induced change in the observed wavelength (or
frequency) of a wave.
, flare - ANSWER Explosive even occurring in or near an active region on the Sun.
dwarf - ANSWER Any star with radius comparable to, or smaller than, that of the Sun
(including the Sun itself).
eclipsing binary - ANSWER Rare binary star system that is aligned in such a way that
from Earth we observe one star pass in front of the other, eclipsing the other star.
Fraunhofer line - ANSWER The collection of over 600 absorption lines in the spectrum of
the Sun, first categorized by Joseph Fraunhofer in 1812.
giant - ANSWER A star with a radius between 10 and 100 times that of the Sun.
GONG project - ANSWER The most extensive study of solar vibrations.
granulation - ANSWER Mottled appearance of the solar surface, caused by rising (hot)
and falling (cool) material convective cells just tbelow the photosphere.
H-R diagram - ANSWER Also known as the Hertzsprung-Russell diagram, a plot of
luminosity against temperature (or spectral class) for a group of stars.
helioseismology - ANSWER The study of conditions far below the Sun's surface through
the analysis of internal "sound" waves that repeatedly cross the solar interior.
inverse-square law - ANSWER The law that a field follows if its strength decreases with
the square of the distance. Fields that follow this decrease rapidly in strength as the
distance increases, bet never quite reach zero.
luminosity - ANSWER One of the basic properties used to characterize stars, luminosity
is defined as the total energy radiated by a star each second, at all wavelengths.
luminosity class - ANSWER A classification scheme that groups stars according to the
width of their spectral lines.
main sequence - ANSWER Well-defined band on the Hertzsprung-Russell diagram on
which most stars are found, running from the top left of the diagram to the bottom right.
Maunder minimum - ANSWER Lengthy period of solar inactivity that extended from 1645
to 1715.
neutrino - ANSWER Virtually massless and chargeless particle that is one of the
products of fusion reactions in the Sun. Neutrinos move at close to the speed of light
and interact with matter hardly at all.
neutrino oscillation - ANSWER Possible solution to the solar neutrino problem, in which
the neutrino has a very tiny mass. In this case, the correct number of neutrinos can be
produced in the solar core, but on their way to Earth some can "oscillate," or become
transformed into other particles, and thus go undetected.
ANSWERS 100% CORRECT
absolute magnitude - ANSWER The apparent magnitude a star would have if it were
placed at a standard distance of 10 parsecs from Earth.
absorption line - ANSWER Dark line in an otherwise continuous bright spectrum, where
light within one narrow frequency range has been removed.
active Sun - ANSWER The unpredictable aspects of the Sun's behavior, such as sudden
explosive outbursts of radiation in the form of prominences and flares.
apparent magnitude - ANSWER The apparent brightness of a star, expressed using the
magnitude scale.
blue giant - ANSWER Large, hot, bright star at the upper-left end of the main sequence
on the Hertzsprung-Russell diagram. Its name comes from its color and size.
chromosphere - ANSWER The Sun's lower atmosphere, lying just above the visible
atmosphere.
convection cell - ANSWER Circulating region of upwelling hot fluid and sinking cooler
fluid in convective motion.
convection zone - ANSWER Region of the Sun's interior, lying just below the surface,
where the material of the Sun is in constant convection motion. This region extends into
the solar interior to a depth of about 20,000 km.
core (of the Sun) - ANSWER The central region of the Sun where nuclear reactions
produce the Sun's energy.
corona - ANSWER One of numerous, large, roughly circular regions on the surface of
Venus, though to have been caused by upwelling mantle material causing the planet's
crust to bulge outward.
coronal hole - ANSWER Vast regions of the Sun's atmosphere where the density of
matter is about 10 times lower than average. The gas there streams freely into space at
high speeds, escaping the Sun completely.
coronal mass ejection - ANSWER Giant magnetic "bubble" of ionized gas that separates
from the rest of the solar atmosphere and escapes into interplanetary space.
Doppler effect - ANSWER Any motion-induced change in the observed wavelength (or
frequency) of a wave.
, flare - ANSWER Explosive even occurring in or near an active region on the Sun.
dwarf - ANSWER Any star with radius comparable to, or smaller than, that of the Sun
(including the Sun itself).
eclipsing binary - ANSWER Rare binary star system that is aligned in such a way that
from Earth we observe one star pass in front of the other, eclipsing the other star.
Fraunhofer line - ANSWER The collection of over 600 absorption lines in the spectrum of
the Sun, first categorized by Joseph Fraunhofer in 1812.
giant - ANSWER A star with a radius between 10 and 100 times that of the Sun.
GONG project - ANSWER The most extensive study of solar vibrations.
granulation - ANSWER Mottled appearance of the solar surface, caused by rising (hot)
and falling (cool) material convective cells just tbelow the photosphere.
H-R diagram - ANSWER Also known as the Hertzsprung-Russell diagram, a plot of
luminosity against temperature (or spectral class) for a group of stars.
helioseismology - ANSWER The study of conditions far below the Sun's surface through
the analysis of internal "sound" waves that repeatedly cross the solar interior.
inverse-square law - ANSWER The law that a field follows if its strength decreases with
the square of the distance. Fields that follow this decrease rapidly in strength as the
distance increases, bet never quite reach zero.
luminosity - ANSWER One of the basic properties used to characterize stars, luminosity
is defined as the total energy radiated by a star each second, at all wavelengths.
luminosity class - ANSWER A classification scheme that groups stars according to the
width of their spectral lines.
main sequence - ANSWER Well-defined band on the Hertzsprung-Russell diagram on
which most stars are found, running from the top left of the diagram to the bottom right.
Maunder minimum - ANSWER Lengthy period of solar inactivity that extended from 1645
to 1715.
neutrino - ANSWER Virtually massless and chargeless particle that is one of the
products of fusion reactions in the Sun. Neutrinos move at close to the speed of light
and interact with matter hardly at all.
neutrino oscillation - ANSWER Possible solution to the solar neutrino problem, in which
the neutrino has a very tiny mass. In this case, the correct number of neutrinos can be
produced in the solar core, but on their way to Earth some can "oscillate," or become
transformed into other particles, and thus go undetected.
