Astronomy 2

Front 1

It would be easier to accurately measure the parallax of a given star from Jupiter than from Earth (though it would take longer). (T or F)

Back 1

True

Front 2

What do you need to measure in order to find the distance to a star by what is called spectroscopic parallax? Question options:

Back 2

Brightness and spectral type (or parallax angle only)

Front 3

If the stars Ain and Suhail have the same apparent brightness, but Ain is 5 times farther away from us than Suhail, then Ain's luminosity is ___________ times the luminosity of Suhail.

Back 3

25 times

Front 4

Compared to stars with cooler surfaces, stars with hot surfaces are

Back 4

Bluer

Front 5

Compared to a main-sequence star of type O, a main-sequence start of type K is:

Back 5

Cooler and Less Massive

Front 6

Suppose that the surface temperature of the Sun were to double. It would have the same luminosity if, at the same time, its radius

Back 6

Decreases to one-quarter its former size

Front 7

Stars with cool surfaces can be very luminous if they are

Back 7

Large

Front 8

What is plotted on an H-R diagram?

Back 8

Luminosity vs. Surface Temperature

Front 9

Red giants are very bright because their surfaces are extremely hot. (T or F)

Back 9

False

Front 10

Albireo is a binary star system consisting of a bright, yellow ("gold") star and a fainter, blue star (it is the official star of the University of California, Berkeley because of its gold and blue colors). Which of the following statements about Albireo must be true?

Back 10

The gold star is significantly larger than the blue star

Front 11

The mass of a star may be determined

Back 11

By studying its orbit around a binary companion

Front 12

A binary star that varies in apparent brightness as one member of the binary passes in front of the other is

Back 12

An eclipsing binary

Front 13

Compared to a star with mass equal to the mass of the Sun, a main sequence star of 10 solar masses is:

Back 13

Hotter and more Luminous

Front 14

The energy of the Sun is produced by

Back 14

Four pretons and two electrons combining to form one helium nucleus

Front 15

The amount of energy released in a nuclear fusion reaction is directly proportional to the

Back 15

Mass difference between the initial components and the final products

Front 16

Theorists predicted that the Sun should be producing a large number of______, but for a long time their measured rate on Earth was substantially less than expected.

Back 16

Neutrinos

Front 17

In its lifetime a star changes all of the hydrogen in its core to energy. (T or F)

Back 17

False

Front 18

It is possible to have a 1-billion-year-old, O-type main-sequence star. (T or F)

Back 18

False

Front 19

A star that is 10 times the mass of the Sun has a luminosity 10,000 times that of the Sun. How does its lifetime compare to the 10 billion year lifetime of the Sun?

Back 19

The lifetime is 1/1000 times as long.

Front 20

Consider the following statements about the three main sequence stars A, B and C.

Star A will be a main sequence star for a total of 4.5 billion years.

Star B has the same luminosity as the Sun.

Star C has a spectral type M.

Which of the following is a true statement about these stars?

Back 20

Star A has the greatest mass

Front 21

In a stable star, the gravitational forces are balanced by

Back 21

Thermal pressure

Front 22

A star like the Sun will end up as a:

Back 22

White dwarf

Front 23

One billion years from now the Sun will be a

Back 23

Main-sequence star

Front 24

In main sequence stars, the pressure to counteract gravity comes primarily from

Back 24

Energy released through the fusion of hydrogen into helium, since hydrogen is readily available and fuses at the central temperatures of stars

Front 25

When a main-sequence star runs out of hydrogen fuel in its core,

Back 25

The core contracts and thus heats up

Front 26

The Sun will leave the main sequence after it has

Back 26

fused nearly all the hydrogen in its inner core to helium

Front 27

H-R diagrams for two clusters of stars, Cluster A and Cluster B, are shown above. From the diagrams, you can tell that Cluster A is

Back 27

Younger

Front 28

A type G main-sequence star evolves to become a red giant. Compared to the way it was when it was on the main sequence, the red giant is

Back 28

More luminous but with a cooler surface

Front 29

Compare the central temperature of a red giant to the central temperature of the main-sequence star from which it evolved. The red giant's center is

Back 29

Much hotter

Front 30

A typical white dwarf is closest in size to:

Back 30

the Earth

Front 31

White dwarf stars

Back 31

in some cases consist largely of carbon and oxygen

Front 32

Fusion in the core of a stable massive star cannot proceed beyond iron because

Back 32

Iron nuclei are the most tightly bound of all nuclei, so iron fusion does not release energy

Front 33

A pulsar is

Back 33

Rotating neutron star

Front 34

Why do millisecond pulsars rotate faster than other observed neutron stars?

Back 34

They are spun up by matter that spirals in to them from their companion star.

Front 35

Which of the following statements about pulsars is true?

Back 35

Pulsars cannot be rotating white dwarfs because their rotation rate is so high that a white dwarf would be ripped apart.

Front 36

A black hole is likely to be the end of stellar evolution for what type of main-sequence star?

Back 36

O

Front 37

What can escape from within a black hole?

Back 37

Neither light nor matter

Front 38

The mass of a black hole candidate can be found by

Back 38

measuring the speed of an orbiting companion and the radius of its orbit

Front 39

A black hole is best defined as

Back 39

any object that is smaller than its event horizon

Front 40

Which of the following statements about known gamma-ray bursts is false?

Back 40

We have shown that some of them are produced by the quantum evaporation of mini black holes.

Front 41

Visual binary:

Back 41

binary system whose stars can bedistinguished with a telescope

Front 42

Spectroscopic binary:

Back 42

observed by a periodic Dopplershift in the spectral lines of each star as the stars orbitcommon center of mass

Front 43

Eclipsing binary:

Back 43

observed by periodic changes in thecombined brightness of the stars as they eclipse each other

Front 44

How much brighter is a star that has a radius 4times larger, but the same temperature?

Back 44

16 times brighter

Front 45

How much brighter is a star that is the same size,but two times hotter?

Back 45

16 times brighter

Front 46

Energy is released in theproton-proton chain when

Back 46

Four hydrogen atoms are fused into helium

Front 47

How is energy generatedin the Sun?

Back 47

Nuclear fusion

Front 48

Compared to the evolutionary track of a star likethe Sun, the track of a high mass star

Back 48

All of the Above

Front 49

This is an image of the Cat’s Eye planetarynebula. What kind of star is at the center?

Back 49

White dwarf

Front 50

Which is the most likely mass of thestar shown in this diagram?

Back 50

12 solar masses

Front 51

This figure shows H-R diagrams for fourstar clusters. Which one is the oldest?

Back 51

B

Front 52

Pulsars usually show all of thefollowing EXCEPT

Back 52

High temperature fusion reactions

Front 53

Suppose that the Sun were suddenlyreplaced by a black hole of exactly thesame mass. What would happen?

Back 53

The Earth and the rest of the planets wouldcontinue to orbit as usual.

Front 54

The event horizon of a black hole

Back 54

is the point from within which light cannot escape

Front 55

nothing

Back 55

nothing