Notes 3 Exam

Question 1

What is luminosity?

Answer 1

total light energy radiated by a star each second-watts

Question 2

Does the luminosity of a star depend on the star’s distance from us?

Answer 2

no

Apparent brightness = how bright an object appears; the farther away a star is the smaller its apparent brightness.

Question 3

From which layer of the sun does the sun’s light come?

Answer 3

core

Question 4

Name the interior parts of the sun.

Answer 4

core, radiation zone, convection zone

Question 5

Name the atmospheric parts of the sun.

Answer 5

Chromosphere, Transition zone, Corona

Question 6

What is the temperature of the sun’s surface?

Answer 6

1,000,000 K

Question 7

What does the chromosphere tell us about the sun?

Answer 7

reveals the elemental composition of the Sun

Question 8

What’s unique about the coronal layer of the sun?

Answer 8

it is brightest in the x-ray portion of the electromagnetic spectrum. sun spots, prominences, solar flares

Question 9

What is the most significant feature about the core of the sun?

Answer 9

source of the sun’s energy

Question 10

What single property of a star determines its final state at “death”?

Answer 10

shell burning

Question 11

What will happen to the sun when it runs out of hydrogen which is hot enough to fuse?

Answer 11

The Sun’s core will contract (shrink) and it will start to fuse helium in the core and hydrogen fusion will start up in a shell round the core. This will heat up the Sun and it its outer layers will therefore expand and it will turn into a red giant.

Question 12

Which two properties allow you to place a star on the Hertzsprung-Russell diagram?

Answer 12

Luminosity and surface temperature (or spectral class)

Question 13

What is a red giant star?

Answer 13

A red giant star is a star with a mass like our Sun that is in the last phase of its life

Question 14

Will the sun ever be a nova? Why or why not?

Answer 14

No, because it is not in a binary system.

Question 15

Will the sun ever be a supernova? Why or why not?

Answer 15

No, because it is not large enough

Question 16

What determines the changes in a star’s life cycle?

Answer 16

the initial mass

Question 17

What is the astronomical origin of the iron in your blood?

Answer 17

a high mass star and supernova

Question 18

Why do supernovas occur?

Answer 18

While the core of a high mass star burns heavier and heavier nuclei, layers of lighter nuclei from the previous stage of burning, are burning in successive shells around that core. When iron is all that’s left in the core, fusion ends and a supernova occurs.

Question 19

What temperature is required for hydrogen fusion? For helium fusion?

Answer 19

10-14 million degrees Kelvin

100 million degrees Kelvin

Question 20

What do all main sequence stars have in common?

Answer 20

-

Question 21

A main-sequence star doesn’t collapse because of the outward _____ produced by hot gases in the stellar interior.

Answer 21

-

Question 22

While a star is on the main sequence, _____ is slowly consumed in the core and _____ builds up.

Answer 22

-

Question 23

At the end of its main-sequence lifetime, a star’s core starts to _____.

Answer 23

shell burn

Question 24

What type(s) of objects remain after a high mass star dies?

Answer 24

neutron star or black hole

Question 25

What type(s) of objects remain after a low mass star dies?

Answer 25

white dwarf will fade and dim like a chunk of charcoal on a grill that is off.

Question 26

When the sun evolves past the main sequence stage of life will its luminosity and surface temperature change? If so, how so?

Answer 26

Yes, it gets brighter and hotter then it dims and gets cooler. Then gets hot and bright again then it cools.