Chapter 12

Question 1

energy per second =

Answer 1

watts

Question 2

apparent brightness =

Answer 2

amount of starlight that reaches the earth

Question 3

brightness = (equation)

Answer 3

luminosity/4pi(distance)^2

Question 4

1 mag star is..

Answer 4

100 times brighter than 6 mag. Star

-smaller the # the brighter the object

Question 5

Venus =

Answer 5

-4

Question 6

full moon =

Answer 6

-12

Question 7

sun =

Answer 7

-27

Question 8

hottest to coolest (spectral type)

Answer 8

O B A F G K M

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Question 9

sun is how many times brighter than the moon?

Answer 9

1 million

Question 10

an HR diagram plots the ______ and ______ of stars

Answer 10

luminosities and temperature

Question 11

how many percent of stars fall in main sequence? (even sun)

Answer 11

90%

Question 12

which stars are the most numerous?

Answer 12

M Stars

Question 13

what type of star is the sun?

Answer 13

G type

Question 14

main sequence stars are fusing _____ into _____ in their cores, like the Sun.

Answer 14

fusing hydrogen into helium

Question 15

Luminous main sequence are

Answer 15

hot (blue)

Question 16

less luminous ones are

Answer 16

cooler, (yellow or red)

Question 17

the mass of a normal hydrogen burning star determines what?

Answer 17

its luminosity spectral type and lifetime

Question 18

high mass main sequence stars

Answer 18

high luminosity
short lived
large radius
blue

Question 19

Low mass main sequence stars

Answer 19

low luminosity
long lived
small radius
red

Question 20

whats the magic number?

Answer 20

10 million

Question 21

when did all stars become larger and redder?

Answer 21

After exhausting their core hydrogen

giants and supergiants

Question 22

what tells us its age?

Answer 22

the main sequence turn off point of a cluster

Question 23

what has no stars with a life expectancy less than around 100 million years

Answer 23

Pleiades