astronomy test 4

the study of waves inside the sun is called blank.

a. photospheric waves

b. solar waveology

c. corona holes

d. helioselsmology

d: helioseismology i

the sun does not expand or contract because it is in a state of blank.

a. coronal equilibrium

b. hydrostatic equilibrium

c. photosphere equilibrium

d. convective equilibrium

b: hydrostatic equilibrium

this part of the sun’s atmosphere averages a temperature about 1,000,000 k

a. corona

b. photosphere

c. spicule

d. chromosphere

a: corona

granulation on the surface of the sun is evidence of

a. seismic activity in the core of the sun

b. magnetic activity in the corona

c. spicules in the chromosphere

d. convection in the photosphere

d: convection in the photosphere

the core of the sun moves energy primarily by convection. true or false

false

in e = mc², the c stands for the blank.

a. speed of sound

b. speed of light

c. energy construction

d. energy of fusion

b: speed of light

the force that holds the nucleus of an atom together is called the blank.

a. weak force

b. e-m force

c. strong nuclear force

d. neutron force

c: strong nuclear force

this is an almost massless particle that is produced during hydrogen fusion

a. proton

b. electron

c. neutrino

d. neutron

c: neutrino

the sun’s source of energy is

a. combustion of hydrogen with oxygen

b. heat generated by gravity

c. fission of heavy elements

d. fusion of hydrogen into helium

d: fusion of hydrogen into helium

cosmic rays are fast moving particles in space. true or false

true

the three step process that creates energy in the sun is called the helium-helium chain. true or false

true

sunspots appear dark because

a. light is prevented from escaping because of the strong magnetic field

b. they are holes in the photosphere of the sun

c. they have a different composition than the surrounding surface of the sun

d. they are cooler than the surrrounding surface of the sun

d: they are cooler than the surrounding surface of the sun

the sunspot cycle going from low point to low point in its cycle takes about blank.

a. 11 yrs

b. 25 yrs

c. 3 yrs

d. 7 yrs

a: 11 yrs

sunspots are blank storms on the surface of the sun

a. hurricane

b. wind

c. tornado

d. magnetic

d: magnetic

the temperature of the sunspots is around 4500 k. true or false

true

a flare is just another term for a sunspot. true or false

false

models of hydrostatic equilibrium have been confirmed by

a. studying the rising and falling of the photosphere of the sun

b. studying gravitational waves emitted by the sun

c. studying the temperature of the oort cloud around the sun

d. sending probes to the interior of the sun

a: studying the rising and the falling of the photosphere of the sun

the sun’s surface is called the blank

a. chromosphere

b. core

c. photosphere

d. corona

c: photosphere

our vision of the interior of the sun is blocked due to blank.

a. the high temperature in the core

b. the outgoing solar wind

c. the high density of the atoms within

d. the brightness of the photons

c: the high density of the atoms within

the density of the atoms within the sun increases as you move outward from the core to the corona. true or false

false

the temperature within the photosphere increases as you move inward toward the core. true or false

true

the dense matter within the sun exists in the blank phase, allowing particles to be packed closer.

a. liquid

b. gas

c. solid

d. plasma

d: plasma

heat is transferred away from the core of the sun by radiation. true or false

true

once a photon is generated in the core, it will blank.

a. remain in the sun forever

b. wander for around 10 million years before generating visible light in the photosphere.

c. always travel back to the interior core to participate in nuclear fusion

d. travel directly to the photosphere within a few days, where it generates the visible light we see

b: wander for around 10 million years before generating visible light in the photosphere

without a source of energy, the sun would blank.

a. continue to expand until it explodes

b. become a neutron star

c. continue burning indefinitely

d. collapse due to gravitational forces

d: collapse due to gravitational forces

geological and fossil evidence on earth tell us the sun has maintained the same luminosity for billions of years. true or false

true

measuring the number of neutrinos coming from the sun can tell us the rate of hydrogen fusion in core. true or false

true

neutrinos from the sun blank.

a. travel near the speed of light and can pass straight through the earth

b. can penetrate only a short distance into the earth

c. will always be stopped by a wall of lead

d. interact with electromagnetic forces

a: travel near the speed of light and can pass straight through the earth

in order for hydrogen fusion in the sun to take place, a neutron must become a proton, with the aid of the strong force. true or false

false

by using blank, astronomers were able to detect and map magnetic fields in the sun.

a. the zeeman effect

b. neutrinos

c. auroas

d. seismic waves

a: the zeeman effect

coronal mass ejections from the sun blank.

a. can seriously disrupt communications and electric power grids

b. all of these choices are correct

c. represent serious hazards for astronauts

d. are fast-moving enormous clouds of ionized gas

b: all of these choices are correct

the baseline used in measuring the parallax of stars is.

a. 2 au

b. 2 parsecs

c. 1 arc second

d. 1 parsec

a: 2 au

the motion along the line of sight is commonly called blank.

a. space motion

b. proper motion

c. transverse velocity

d. radial motion

d: radial motion

this is the motion of the star with respect to the background stars.

a. radial motion

b. space motion

c. proper motion

d. transverse velocity

c: proper motion

the earth-sun distance is known as a

a. light year

b. parsec

c. kilometer

d. astronomical unit

d: astronomical unit

hipparchus used triangulation to estimate the distance to the moon. true or false

true

the process of using the transit of venus to determine distance to the sun was devised by blank.

a. jeremiah dixon

b. charles mason

c. edmund halley

d. hipparchus

c: edmund halley

the parsec represents blank.

a. an arc-minute

b. the apparent shift of a star relative to background stars

c. the same distance as a light year

d. just over 3 light-years

d: just over 3 light years

the total amount of energy that a star emits each second is called its

a. luminosity

b. apparent brightness

c. astro energy

d. apparent magnitude

a: luminosity

the brightness of a star at 10 parsecs is called the stars blank.

a. parsec magnitude

b. apparent luminosity

c. absolute magnitude

d. apparent brightness

c: absolute magnitude

the person who first started the magnitude scale for stars was blank.

a. kepler

b. copernicus

c. aristotle

d. hipparchus

d: hipparchus

absolute magnitude is the brightness of a star in the night sky. true or false

false

luminosity is expressed in watts or wattage. true or false

true

the surface temperature of an o-type star is around blank.

a. 12,000 k

b. 30,000 k

c. 3000 k

d. 6000 k

b: 30,000 k

the hotter the star, the bluer it appears. this is a consequence of blank.

a. wiens law

b. stefans law

c. keplers law

d. plancks law

a: wiens law

m-type stars have a surface temperature of about blank.

a. 6000 k

b. 30,000 k

c. 3000 k

d. 12000 k

c: 3000 k

the balmer lines in a spectrum are the signature of

a. mercury

b. hydrogen

c. calcium

d. helium

b: hydrogen

our sun is a g-type star. true or false

true

the star temperature classification that is just cooler than the sun is the f-class star. true or false

this type of binary star system is detected by using the doppler shift

a. visual binary

b. spectral binary

c. eclipsing binary

d. apparent double star

b: spectral binary

binary stars are used to measure blank.

a. temperature

b. mass

c. distance

b: mass

two orbiting stars revolve around a point of balance called the blank.

a. center of light

b. center of rotation

c. center of mass

d. center of revolution

c: center of mass

stars whose absorption lines move back and forth are called blank.

a. astrometry binaries

b. visual binaries

c. spectroscopic binaries

d. eclipsing binaries

c: spectroscopic binaries

apparent double stars are 2 stars going around each other. true or false

false

40 percent of visible stars are binary systems. true or false

true

we can measure the temperature of a star by

a. determining its spectral type

b. observing it in a binary

c. measuring its doppler shift

d. imaging its photosphere

a: determining its photosphere

molecular absorption lines indicate a star is which of the following spectral types

a. b

b. o

c. l

d. g

c: l

measuring the orbital period and semimajor axis o binary star will give us each stars own mass. true or false

false

the overall brightness of a star differs from luminosity in that blank.

a. brightness remains the same no matter the size of the star

b. luminosity is expressed in kelvin

c. brightness depends on the distance to the star

d. brightness is equal to the distance squared over watts generated

brightness depennds on the distance to the star

in astronomy, a standard candle is a star blank.

a. whose luminosity is well-determined

b. that fluctuates in color

c. with a known distance

d. that only exists outside our galaxy

a: whose luminosity is well-determined

the temperature and composition of stars photosphere can be determined from the properties of its starlight. true or false

true

the absorption lines in a stars spectral signature give insight into its composition because blank.

a. only bright emission spectra can give insight into a stars composition

b. different elemental gases absorb photon energy on different frequencies

c. photons do not emit enough energy to be visible in a spectral signature

d. a dark absorption line within an elements normal frequency indicates its absence from the star

b: different elemental gases absorb photon energy on different frequencies

scientists have recently defined three new stellar spectral types l, t, and y, which describe objects blank.

a. much hotter than o-class stars

b. called brown dwarfs

c. with temperatures between those of a- and f- class stars

d. just hotter than our sun

b: called brown dwarfs

if you know a stars temperature and use the stefan-boltzmann law you can find blank.

a. luminosity

b. distance

c. size

d. mass

a. luminosity

a technique to find diameters of stars using short exposures is called

a. parallax

b. speckle interferometry

c. mass interferometry

d. luminosity measurements

b: speckle interferometry

using the stefan-boltzmann law to find luminosity requires blank.

a. velocity and distance

b. period and temperature

c. radius and temperature

d. brightness and radius

c: radius and temperature

the technique of combining the light from two or more smaller telescopes to obtain that is equivalent to that of much larger telescope is called

a. interferometry

b. speckle imaging

c. angular resolution

d. adaptive optics

a: interferometry

eclipsing binaries cannot be used to measure masses of stars. true or false

false

an eclipsing binary can tell us each stars radius if we observe

a. the eclipse duration and orbital speed

b. the angular separation between the stars

c. the frequency of eclipses

d. the relative darkness of the two eclipses

a: the eclipse duration and orbital speed

speckle imaging techniques help increase image resolution by

a. realigning many atmospheric refracted telescopic images to reconstruct a single image

b. collecting light from a location in space, outside of earths atmosphere

c. rapidly adjusting optics to compensate for atmospheric changes on earth

d. combining the light from two or more smaller telescopes

a: realigning many atmospheric refracted telescopic images to reconstruct a single image

a plot of surface temperature vs luminosity for stars is known as the blank

a. hr diagram

b. einstein graph

c. luminosity graph

d. mass graph

a: hr diagram

blank of stars will lie on the main sequence

a. 90%

b. 45%

c. 50%

d. 75%

a: 90%

blank are small, bright, dead cores of stars like our sun

a. white dwarf

b. white holes

c. black holes

d. neutron stars

a: white dwarfs

a main sequence star has a luminosity class of

a. v

b. III

c. IV

d. lb

a: v

most stars are not on the main sequence. true or false

false

more luminous stars on the main sequence are smaller in size. true or false

false

stars that are forming are called blank. ‘

a, proto bodies

b. protoplanets

c. newbies

d. protostars

d: protostars

stars that pulsate in and our are called blank.

a. protostars

b. protoplanets

c. variable stars

d. pulsating clouds

c: variable stars

a cloud of ejected gas sourrounding a dying star is called a blank.

a. star cloud

b. reflection nebula

c. absorption nebula

d. planetary nebula

d: planetary nebula

the proper sequence of stages in the life of a main sequence star is

a. protostar, red giant, main sequence

b. red giant, main sequence, protostar

c. red giant, protostar, main sequence

d. protostar, main sequence, red giant

d: protostar, main sequence, red giant

our sun will die as a white dwarf. true or false

true

stellar computer models help us trace a stars life from birth to death. true or false

true

according to the stefan-boltzmann law, if two stars with the same surface temperature have different luminosities, then blank.

a. the less luminous one must have a larger surface area

b. the more luminous one must have a larger radius

c. the more luminous one must be farther away from the viewer

d. the more luminous one must be closer to the viewer

b: the more luminous one must have a larger radius

north star, polaris, is a blank.

a. blue giant star

b. yellow main sequence star

c. yellow giant, variable star

d. white main sequence star

c: yellow giant, variable star

on the hr diagram, the luminosity of stars is compared to the luminosity of the sun in powers of 10. true or false

true

stars near the same position on the hr diagram have approximately the same mass. true or false

true

a stars life cycle ultimately depends upon its mass. true or false

true

the best place to find star information is in a blank.

a. nebula

b. molecular cloud

c. nova

d. supernova

b: molecular cloud

when a new star ejects gas in opposite directions, this is known as blank.

a. tri flow

b. opposite flow

c. ejection flow

d. bipolar flow

d: bipolar flow

objects with masses between about 0.08 and 0.016 times the mass of the sun are called

a. red dwarfs

b. brown dwarfs

c. white dwarfs

d. yellow dwarfs

b: brown dwarfs

a stars first energy source comes from gravitational collapse. true or false

true

the lower limit for a normal star is about 1 solar masses. true or false

true

the dust in molecular clouds contains

a. only microscopic metal particles

b. heavy, radioactive elements like uranium

c. ice and particles of silicates, carbon and iron

d. particles of carbonate and oxide minerals

c: ice particles and silicates, carbon and iron

a molecular cloud contains mainly hot gases. true or false

false

a protostar is heated to fusing temperature by

a. gravitational influence of nearby protostars

b. radioactive decay of elements within the cloud

c. high speed jets of gas flowing through them

d. compression and accretion of materials due to gravitational collapse

d: compression and accretion of materials due to gravitational collapse

a protostar becomes a main sequence star when

a. the gravitational force between accreting particles first begins to cause it to collapse

b. hydrogen begins fusing into helium within its core

c. it fluctuates in brightness as a t-tauri star

d. fusion of deuterium begins

b: hydrogen begins fusing into helium within its core

the sun is expected to live about blank years.

a. 10 million

b. 10 thousand

c. 10 trillion

d. 10 billion

d: 10 billion

stars with less than about 0.4 times the mass of the sun are probably

a. convective only in the core

b. fully convective

c. fully functional

d. fully radiative

b: fully convective

the stars with the shortest main sequence lifetimes will be

a. the lowest mass stars

b. the highest mass stars

c. the coolest stars

d. stars like the sun

b: the highest mass stars

very massive stars live relatively short lives. true or false

true