Astr-104 Final

Front 1

The light we receive from the Sun comes from the layer of the Sun's atmosphere called the

Back 1

Photosphere

Front 2

The wavelength peak of the Sun's radiation is in the middle of the

Back 2

visible spectrum

Front 3

About 94 percent of the nuclei in the outer parts of the Sun are

Back 3

hydrogen

Front 4

Magnetic storms on the Earth are caused by

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solar flares

Front 5

As the solar atmosphere expands outward into interplanetary space it becomes the

Back 5

corona

Front 6

The dark region of a sunspot is often surrounded by a less dark region called the

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penumbra

Front 7

Dark lines threading their way across the Sun, visible in Ha light near sunspots are

Back 7

filament

Front 8

The orientation of the Sun's magnetic field changes, repeating a full cycle every

Back 8

22 years

Front 9

The temperature of the Sun's photosphere is about

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6000 K

Front 10

The prominent absorption lines in the optical solar spectrum are called ___________ lines.

Back 10

Both b and c

Front 11

When a solid body is heated the result is a(n)

Back 11

continuous spectrum

Front 12

Categories of stars based on their respective spectra are called

Back 12

spectral types

Front 13

Our Sun is of spectral type

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G2

Front 14

What two things determine the apparent magnitude of a star?

Back 14

intrinsic brightness, distance from the observer

Front 15

The angle at which a star appears to move when observed from the ends of a baseline of I A.U. is the star's

Back 15

parallax

Front 16

The magnitude a star would have if it were at a standard distance of 10 parsecs is its

Back 16

absolute magnitude

Front 17

A star that is 40 parsecs from the Sun would, if moved to a distance of 10 parsecs, be

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16 times brighter

Front 18

A temperature-luminosity diagram of stars usually includes a diagonal band called the

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main sequence

Front 19

The angular rate of the change of position of a star in the sky is its

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proper motion

Front 20

The size of a single star can be determined if we know its absolute magnitude and its

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temperature

Front 21

A star which appears double when observed directly, and is held together by mutual gravitation is called a(n)

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visual binary

Front 22

A binary star which varies in brightness as one component passes in front of the other is a(n)

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eclipsing binary

Front 23

The main value in the study of binary stars is the ability it gives us to determine stellar

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masses

Front 24

Common red giant variable stars such as Mira that vary slowly in brightness are called

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long-period variables

Front 25

The period-luminosity relation applies to

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Cepheid variables

Front 26

Star clusters with irregular shapes, and containing relatively young stars, are called

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open clusters

Front 27

Star clusters made of many thousands of older stars are called

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globular clusters

Front 28

The age of an open cluster can be determined from its

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temperature-luminosity diagram

Front 29

All RR Lyrae stars have the same ___________ magnitude.

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absolute magnitude

Front 30

The least massive stars are about ___________ percent as massive as the Sun.

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8

Front 31

One class of low-mass, erratically variable pre-main-sequence stars is called

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T Tauri stars

Front 32

The particles in the following list that are not a part of the structure of an atom are

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photons

Front 33

When an atom loses an electron, it becomes a(n)

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ion

Front 34

The number of protons in nucleus of an atom of 146C is

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6

Front 35

If normal carbon is 126C, the number of electrons in singly-ionized carbon will be

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5

Front 36

The neutral particle with little or no mass that is given off during nuclear reactions is called a(n)

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neutrino

Front 37

The process of building heavier atoms from lighter ones is called

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nucleosynthesis

Front 38

In a main-sequence star, the gravitational forces are balanced by

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thermal pressure.

Front 39

The nuclei of atoms are held together by

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strong force.

Front 40

Compared with low-mass stars, high-mass stars have main-sequence lifetimes that are

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shorter

Front 41

Stars retaining less than 1.4 solar masses after their unstable phase will become

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white dwarfs

Front 42

Planetary nebulae are called that because

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they appear similar to planets when observed in a small telescope.

Front 43

As a white dwarf ages it will

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cool

Front 44

A very massive star at the end of its main sequence life becomes a

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red supergiant

Front 45

When the core of a massive star collapses, rebounds, and explodes into a supernova, it picks up much of its energy from the outflow of

Back 45

neutrinos

Front 46

No supernovae have been seen in our Milky Way Galaxy since

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1604

Front 47

The progenitor of Supernova 1987A was a(n)

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blue supergiant.

Front 48

The final proof of the nature of pulsars came from observations of the

Back 48

Crab Nebula.

Front 49

Although they were first expected to be extremely stable and constant, it was discovered that pulsars

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gradually slow down.

Front 50

Gravitational waves were first directly detected using Earth-based detectors in

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Gravitational waves have not yet been detected.

Front 51

While studying the distribution of globular clusters, Harlow Shapley discovered that we are not in the

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center of the Galaxy.

Front 52

The "spiral arms" of the Galaxy are embedded in the

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disk

Front 53

The mechanism that may have created the spiral arms of our Galaxy by piling up material to create new stars is called the

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density wave.

Front 54

Stars in the galactic halo are generally

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very old.

Front 55

In which of the following parts of the electromagnetic spectrum are we learning the least about the very center of our Galaxy?

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visible light

Front 56

To trace out the spiral structure of our Galaxy we should look at

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very young objects.

Front 57

The symbol H II would denote a hydrogen atom with a charge of

Back 57

+1.

Front 58

Because molecular hydrogen is difficult to detect, astronomers map the distribution of molecular material in our Galaxy with observations of the more easily detectable molecule

Back 58

CO

Front 59

A heavily-studied giant molecular cloud is in

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Orion

Front 60

Which of the following has not been detected in interstellar space?center of the Galaxy.

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DNA

Front 61

Classification of spiral galaxies into subtypes is based on

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how tightly wound the spiral arms are.

Front 62

The type of galaxy with typically the most dust and gas is

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irregular

Front 63

If enough mass is present in a small enough volume at the center of a galaxy, it implies the presence of

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a black hole.

Front 64

The largest nearby cluster of galaxies is the

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Virgo cluster.

Front 65

A cluster of galaxy clusters is called a

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supercluster

Front 66

If a galaxy is moving away from us at 7100 km/sec, it must be (assuming Ho= 71 km/s/Mpc) at a distance of

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100 Mpc.

Front 67

The length of time light from a galaxy has been traveling through space in order to reach us is the galaxy's

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lookback time.

Front 68

A spectral line at 1000 Å is seen at what wavelength when its redshift is 5?

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6000 Å

Front 69

Which of the following are primary distance indicators?

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Cepheid variables

Front 70

The fact that circular velocity does not decrease at galactic radii greater than that of the Sun indicates that our Galaxy

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is more massive than previously believed.