Deck 9: The Family of Stars

Question 1

The classification of stellar spectra started with the amount of hydrogen in the star's spectrum; however, now a better scheme uses the star's _____.

A) mass
B) diameter
C) radius
D) temperature
E) luminosity

Answer 1

D

Question 2

A star's apparent magnitude is a measure of how bright it appears to us if it is at its actual distance.

Answer 2

True

Question 3

The formula $m _ { V } - M _ { V }$  can be used to calculate a star's _____.

A) mass
B) distance
C) rotation speed
D) revolution period
E) diameter

Answer 3

distance

Question 4

The spectral classification of stars started with the amount of hydrogen present in their spectra, but a better method now uses the amount of oxygen in the star's spectra.

Question 5

Careful measurements reveal that a star maintains a steady apparent brightness at most times, except that at precise intervals of 93 hours. the star becomes dimmer for about 2 hours. The most likely explanation for this is that the star ________.

A) has a very large "sunspot" on its surface
B) is a member of an eclipsing binary star system
C) is a white dwarf
D) is a Cepheid variable
E) is periodically ejecting gas into space, every 93 hours

Question 6

The Hertzsprung-Russell Diagram is a plot for stars using absolute magnitude versus temperature.

Question 7

All stars produce an absorption spectra.

Question 8

The most accurate way to determine the surface temperature of a star is to study the pattern of emission lines from various atoms.

Question 9

S tars of low luminosity will always have large positive absolute magnitude.

Question 10

Recent discoveries of two types of brown dwarfs have placed these stars near which spectral type of star?

A) hotter than O stars
B) cooler than O stars
C) hotter than M stars
D) cooler than M stars
E) at exactly the same level as G stars

Question 11

Which star has the highest density (mass per unit volume)?

A) white dwarf
B) main sequence
C) supergiant
D) red giant
E) regular giant

Question 12

If two stars are emitting the same amount of light, the star that is farther will appear dimmer.

Question 13

If a star has an apparent magnitude of +5 and an absolute magnitude of -10, what can we say about that star?

A) The star is farther than 10 parsecs away.
B) The star is closer than 10 parsecs away.
C) The star has a very large chromosphere.
D) The star has a very large corona.
E) The star is fainter than the Sun.

Question 14

Our Sun's spectral temperature type is classified as a(n) ____ on the spectral sequence.

A) O star
B) F star
C) G star
D) K star
E) M star

Question 15

Recently discovered brown dwarfs have spectra similar to cool O-type stars.

Question 16

The Hertzsprung-Russell diagram can be labeled many different ways. Which coordinates CANNOT be used on an H-R diagram?

A) luminosity versus spectral type
B) luminosity versus temperature
C) radius versus temperature
D) absolute magnitude versus temperature
E) luminosity versus color

Question 17

Which star has the largest diameter?

A) white dwarf
B) main sequence
C) red giant
D) supergiant
E) regular giant

Question 18

The luminosity class is assigned to a star by studying the absorption lines in the spectrum of the star.

Question 19

In which spectral sequence are the hottest stars categorized?

A) O stars
B) B stars
C) A stars
D) F stars
E) K stars

Question 20

A star's absolute brightness is calculated at a standard distance of 10 parsecs.

Question 21

The stellar parallax limit for ground-based telescopes is accurate for stars closer than ____.

A) 10 parsecs
B) 50 parsecs
C) 100 parsecs
D) 200 parsecs
E) 500 parsecs

Question 22

The least common type of star is a(n) ____.

A) white dwarf
B) lower main sequence
C) upper main sequence
D) giant
E) supergiant

Question 23

Veg a i s a n A 0 main sequence star . Base d o n thi s informatio n, whic h statement is true?

A) Vega has a surface temperature that is less than the Sun
B) Vega has mass that is greater than the Sun
C) Vega is less luminous than the Sun
D) Vega has mass that is less than the Sun
E) Vega is located near the lower right hand corner on the HR diagram

Question 24

The most common type of star is a(n) ____.

A) white dwarf
B) lower-main-sequence star
C) upper-main-sequence star
D) giant
E) supergiant

Question 25

How did astronomers discover the relationship between spectral type and mass for main sequence stars?

A) by measuring stellar radii with very powerful optical telescopes
B) by measuring stellar radii with very powerful radio telescopes
C) by comparing stars with the same spectral type but different luminosities
D) by using computer models of hydrogen fusion and stellar structure
E) by measuring the masses and spectral types of main-sequence stars in binary systems

Question 26

The Balmer series of hydrogen absorption lines in stars is located in what part of the electromagnetic spectrum?

A) gamma ray region
B) ultraviolet region
C) visible region
D) infrared region
E) microwave region

Question 27

Which type of binary system have pairs of stars that are so close together that they look like one single point?

A) radio binary
B) eclipsing binary
C) visual binary
D) spectroscopic binary
E) neutron star binary

Question 28

A star's absolute visual magnitude depends only on the star's ______ and _____.

A) temperature; mass
B) diameter; mass
C) temperature; density
D) diameter; density
E) distance; magnitude

Question 29

Groombridge 34 i s an M2 main sequence star . Base d o n thi s informatio n, whic h statement is true?

A) Groombridge 34 has a surface temperature that is more than the Sun.
B) Groombridge 34 has mass that is greater than the Sun.
C) Groombridge 34 is less luminous than the Sun.
D) Groombridge 34 is more luminous than the Sun.
E) Groombridge 34 is located near the upper left hand corner on the HR diagram.

Question 30

The hydrogen lines of spectral type A main sequence stars are ____.

A) the strongest
B) the weakest
C) the most narrow
D) useful in determining apparent magnitude
E) used to estimate the luminosity of the star

Question 31

How do astronomers determine the distance to stars that are farther than 100 parsecs away?

A) measuring the shift of the stellar parallax
B) estimating a star's spectral type and comparing it to the spectroscopic parallax
C) subtracting absolute from apparent magnitudes
D) using trigonometry in the triangulation method
E) measuring the proper motion of a star

Question 32

The Sun is what spectral type?

A) S2
B) G2
C) F2
D) K2
E) ST2 (Spectral Type 2)

Question 33

On the H-R diagram, 90 percent of all stars are ____.

A) either giant or supergiant stars
B) white dwarfs
C) main sequence stars
D) sred dwarfs
E) binary stars

Question 34

Any star that is more luminous than the Sun, but has the same temperature as the Sun, is a(n) ____.

A) pulsating star
B) white dwarf
C) zero age main sequence star
D) giant
E) brown dwarf

Question 35

Absolute visual magnitude is calculated at a standard distance of ____.

A) one light year
B) one parsec
C) 10 light years
D) 10 parsecs
E) 100 parsecs

Question 36

A supergiant star's radii may extend out to the _____.

A) half the orbit of Mercury
B) orbit of Mercury
C) orbit of Venus
D) orbit of the Earth
E) orbit of Saturn

Question 37

On the H-R diagram, lines of constant radius are illustrated as _____.

A) sloping downward from right to left
B) sloping downward from left to right
C) running vertically on the right side
D) running horizontally on the top
E) moving in various direction depending on the type of star

Question 38

Remember Kepler's third law, which relates the period of revolution to the average distance to a planet.   How do we modify that law to use with binary stars?

A) Add the total mass of the two stars.
B) Add Newton's Law of Gravitation.
C) Add Einstein's Law of Relativity.
D) Add the difference of their masses.
E) Add the distance between the two stars.

Question 39

The luminosity of a star is the ____.

A) total energy radiated by the star at 100 parsecs
B) total energy radiated by the star
C) total energy radiated by the star in one second
D) average energy radiated by the star in one month
E) average energy radiated by the star in one year

Question 40

Hydrogen lines are weak in the spectra of hot O-type stars because ____.

A) most of the hydrogen has been converted to helium
B) a good spectrum of these stars is difficult to obtain
C) these stars have no atmosphere
D) gravitational pressure pushes all the hydrogen lines out of the visible spectrum
E) most of the hydrogen is ionized to high energy levels

Question 41

A star's absolute visual magnitude depends on its _______________ and _______________.

Question 42

In the above, which figure represents stars with the longest main-sequence lifetimes? Note: (C) represents the entire main sequence while (D) and (E) represent only small parts of the main sequence.

Question 43

On the H-R diagram, 90 percent of all stars are _______________.

Question 44

In the accompanying figure, which region represents stars that have ceased ongoing nuclear fusion? Note: (C) represents the entire main sequence while (D) and (E) represent only small parts of the main sequence.

Question 45

In the accompanying figure, which region represents white dwarfs? Note: (C) represents the entire main sequence while (D) and (E) represent only small parts of the main sequence.

Question 46

The horizontal axis (X-axis) of the Hertzsprung-Russell diagram is labeled with _______________.

Question 47

The vertical axis in the accompanying figure is labeled _____.

A) temperature
B) radius
C) apparent visual magnitude
D) absolute visual magnitude
E) mass

Question 48

Th e apparen t magnitud e o f a sta r observe d fro m a distanc e o f 1 0 pc is called _____.

Question 49

If luminosity depends on radius and temperature, what does flux depend on?  _______________

Question 50

The least common stars are _______________ stars.

Question 51

One type of binary star is _______________ binary.

Question 52

In the accompanying figure, which region represents the largest diameter stars? Note: (C) represents the entire main sequence while (D) and (E) represent only small parts of the main sequence.

Question 53

The sloped lines from top left to bottom right in the accompanying figure are labeled ____.

A) temperature
B) radius
C) apparent magnitude
D) absolute magnitude
E) mass

Question 54

The horizontal axis in the accompanying figure is labeled _____.

A) temperature
B) radius
C) apparent magnitude
D) absolute magnitude
E) luminosity

Question 55

In the accompanying figure, which region represents approximately 80 percent of normal stars? Note: (C) represents the entire main sequence while (D) and (E) represent only small parts of the main sequence.

Question 56

In the accompanying figure, which region represents stars that are extremely bright and emit most of their radiation as ultraviolet light? Note: (C) represents the entire main sequence while (D) and (E) represent only small parts of the main sequence?

Question 57

Explain why the current spectral classification letters are all jumbled and not in alphabetical order.

Question 58

The most common stars are _______________ stars.

Question 59

The luminosity (L) of a star is the total energy the star radiates in _______________.

Question 60

The vertical axis (Y-axis) of the Hertzsprung-Russell Diagram is labeled with _______________.

Question 61

Explain the difference between apparent visual brightness and absolute visual brightness.

Question 62

Stellar spectra started with the amount of hydrogen found in the star's spectrum and started with the letters A through Q.  What are the current letters used to classify stellar spectra?

Question 63

A star has a parallax angle of 0.019 seconds of arc.  How far away is this star from Earth?

Question 64

List the three types of binary stars.

Question 65

Explain why it would be better to obtain stellar parallax for stars if we could observe from the planet Mars instead of the Earth.

Question 66

Briefly state or explain the mass-luminosity relation for stars.

Question 67

Determine the mass of a theorized black hole from the following information. The mass of the companion main sequence star is 6 solar masses. The observed period and semi-major axis of the binary system are 3.5 years and 5.5 AUs, respectively.

Question 68

Star A has an apparent visual magnitude of +5 and an absolute visual magnitude of -4.   What is the distance to Star A?

Question 69

In the accompanying figure, which region represents supergiant stars? Note: (C) represents the entire main sequence while (D) and (E) represent only small parts of the main sequence.

Question 70

Star B has an apparent visual magnitude of +5 and is at a distance of 330 pc.   What is the absolute visual magnitude of Star B?