Earth Science, Tarbuck Chap 23

Question 1

What is the Hertzsprung-Russel Diagram

Answer 1

Describes stars and places them on a graph based on Luminosity, Surface temperature, and apparent magnitude

Question 2

What are nebulae

Answer 2

interstellar clumps of matter, rich in dust and gases,

Question 3

What are molecular clouds

Answer 3

clouds cold and dense enough for hydrogen atoms
to join together into hydrogen molecules

Question 4

List the usual evolution of a star

Answer 4

Molecular Cloud -> Protostar -> Main-Sequence Star -> Red Giant -> Planetary Nebula -> White Dwarf -> Black Dwarf

Question 5

How does a protostar form

Answer 5

When the Molecular Cloud collapse, gravitational energy is converted into thermal energy. This causes the gasses to increase in temperature and radiate energy.

Question 6

Difference between Protostars and Stars

Answer 6

Protostars are not hot enough to begin nuclear fission.

Question 7

What is the proton-proton chain reaction

Answer 7

Hydrogen nuclei fuse with helium nuclei to begin hydrogen fusion

Question 8

What marks the transition from a Protostar to a main-sequence star

Answer 8

When a protostar begins hydrogen fusion, this causes an outward gas pressure that balances the inward pull of gravity

Question 9

What causes a main-sequence star to turn into a red-giant

Answer 9

When hydrogen in the star’s core is consumed, gravity prevails and the star begins to collapse which causes temperatures to rise even more. As this occurs, a even more vigorous version of hydrogen fusion occurs in the shell surrounding the core.

Question 10

What is Core helium fission

Answer 10

During the red-giant phase of a star, as the core reaches 100 million kelvins, which uses 3 helium nuclei into one carbon nucleus plus energy.

Question 11

Stars use Hydrogen and then Helium and then carbon to initiate nuclear fission and produce heat but at what point does a star run out of energy

Answer 11

When the stars core is primarily composed of iron, it cannot fuse the iron to create more energy

Question 12

How does a low-mass star die

Answer 12

They skip the Red-Giant Phase and turn into a white dwarf directly as the star cools

Question 13

What is a low-mass star also called

Answer 13

Red-Dwarf

Question 14

How does middle-mass star die

Answer 14

After the red giant phase, they cast off their bloated outer atmospheres, which creates an expanding cloud of gas called a planetary nebula. In the middle of the planetary nebula lies the stars hot core, a white dwarf

Question 15

What is a supernova

Answer 15

When a high mass star dies, it releases the energy formed by the collapse of the iron core and the star explodes

Question 16

What happens to a High mass star after it dies

Answer 16

either becomes neutron star or black hole

Question 17

What are white dwarfs

Answer 17

Dead star’s cores that are super dense because the core collapsed on itself. The surface of white dwarfs are extremely hot. The surface of white dwarfs are usually white or bluish in color.

Question 18

What are black dwarfs

Answer 18

White dwarfs that have used all of their thermal energy and grown cold

Question 19

What is a neutron star

Answer 19

cores of massive stars, product of explosive supernova events. Occurs when a star is massive enough where the core is able to overcome the degeneracy pressure and the core of a massive star collapses, which causes electrons are forced to combine with the protons located inside the nucleus to produce neutrons

Question 20

What is degeneracy pressure

Answer 20

force that counteracts gravitational collapse in dense astronomical objects like white dwarfs