Hertzsprung and Russell

Question 1

Why are the majority of stars found along the main sequence?

Answer 1

-more time is spent as a main sequence
-the universe isn’t old enough for many stars to become white dwarfs

Question 2

What type of fusion is occurring for stars along the Main Sequence?

Answer 2

nuclear fusion

Question 3

Why are there so few stars in the Hertzsprung gap?

Answer 3

stars move through this section quickly

Question 4

Describe how the main sequence stars of the Hertzsprung-Russell diagram are arranged in the diagonal band pattern

Answer 4

-if you have more mass, you will be hotter and brighter

Question 5

Properties of red giants

Answer 5

-low surface temp (3000 celsius)
-absolute magnitude around 5

Question 6

In the early years, astronomers thought stars moved along the main sequence from their formation until their end. What do astronomers think today?

Answer 6

a star stays in one place until almost all its hydrogen fuel is used up

Question 7

Define “solar mass”

Answer 7

unit of measure. equal to the mass of the Sun

Question 8

As a main sequence star ages, why does gravity at its core begin to increase?

Answer 8

the core becomes more dense because the outer laters have more gravity compression

Question 9

The nuclear fusion that powers a star takes place in its core. Describe how the expanding outer layers of a red giant begin to cool.

Answer 9

since the Sun’s core is so far beneath the surface, the outer layers begin to cool

Question 10

What are the heaviest elements that can form in a red giant?

Answer 10

carbon and oxygen

Question 11

Describe how a red giant creates elements such as carbon and oxygen

Answer 11

helium fusion

Question 12

Describe how a red giant becomes a white dwarf

Answer 12

-as an expanding red giant sends streams of gas and dust into space it begins to lose mass
- a star with an initial mass of up to 10 solar masses will lose enough mass to become a stable white dwarf

Question 13

Under what circumstances does a white dwarf become a black dwarf?

Answer 13

white dwarfs radiate energy into space, becoming cooler and dimmer until its light goes out, where it then is a black dwarf

Question 14

What characteristics of the Spirograph nebula suggest that it is the birthplace of new stars?

Answer 14

the dark patches represent the clumping of matter, which can form stars

Question 15

If a star’s initial mass is greater than 10 solar masses, what 2 types of “stars” will evolve?

Answer 15

-neutron star or black hole

Question 16

Mass boundaries for neutron stars and black holes

Answer 16

-neutron stars: 10-50 solar masses
-black holes: over 50

Question 17

How do heavy elements form?

Answer 17

the energy from a supernova is great enough to drive the fusion and formation of elements heavier than iron

Question 18

What is a neutron star?

Answer 18

-neutron stars are created when a star’s initial mass is 10-50 solar masses
-forms when a massive star runs out of fuel and collapse

Question 19

What is a pulsar?

Answer 19

pulsars are a type of neutron star that send out light and a beam of very high-energy radio waves

Question 20

A star has a mass that is greater than 50 solar masses. Describe the process that this star goes through to become a black hole

Answer 20

• will become a supernova and produce elements heavier than iron
  -if the mass of the material left behind is greater than 4 solar masses, the core will collapse in on itself
  -the object has immense gravitational pull, becoming a black hole

Question 21

Why is the evidence we use to identify a black hole considered to be indirect evidence?

Answer 21

the first black hole was discovered by studying a binary star. a blue giant and its invisible companion, an x-ray source in the constellation Cygnus

Question 22

Arrange the following terms in their correct sequence: red giant, nebula, formation of helium, white dwarf, main sequence star, formation of clumps of matter, formation of carbon, hydrogen

Answer 22

formation of clumps of matter -> main sequence star -> formation of helium -> red giant -> formation of carbon, hydrogen -> white dwarf -> nebula

Question 23

Stars over 10 solar masses begin the fusion of carbon and can produce nickel and iron. However, using iron as a fuel has been said to be as efficient as using a rock as a fuel. Explain why.

Answer 23

Nickel and iron take more energy to produce then fuse