Mastering Astronomy Chapter 14 Assignment

Listed following are the different layers of the Sun. Rank these layers based on their distance from the Sun's center, from greatest to least.

Corona

Chromosphere

Photosphere

Convection Zone

Radiation Zone

Core

Rank the layers of the Sun based on their density, from highest to lowest.

Core

Radiation Zone

Convection Zone

Photosphere

Chromosphere

Corona

Rank the following layers of the Sun based on their temperature, from highest to lowest.

Core

Radiation Zone

Convective Zone

Photosphere

Rank the following layers of the Sun based on the pressure within them, from highest to lowest.

Core

Radiation Zone

Convective Zone

Photosphere

In which of the following layer(s) of the Sun does nuclear fusion occur?

Core

Which of the following layers of the Sun can be seen with some type of telescope? Consider all forms of light, but do not consider neutrinos or other particles.

-photosphere

-chromosphere

-corona

Nuclear fusion of hydrogen into helium occurs in the_____________

core

Energy moves through the Sun's _______________ by means of the rising of hot gas and falling of cooler gas.

convection zone

Nearly all the visible light we see from the Sun is emitted from the ________

photosphere.

Most of the Sun's ultraviolet light is emitted from the narrow layer called the __________ where temperature increases with altitude.

chromosphere

We can see the Sun's ______________ most easily during total solar eclipses.

corona

The _____________ is the layer of the Sun between its core and convection zone.

radiation zone

To understand the interplay of observations and models you must first be able to distinguish between things that we observe and things that we infer from models. Consider the following statements about the Sun. Classify each statement as an observation or as an inference based on the current, accepted model for the Sun.

Observations:

-The photosphere is made mostly of hydrogen and helium.

-The photosphere emits mostly visible light.

-The corona is hotter than the photosphere.

-The Sun emits neutrinos.

Inferences from a model:

-The Sun generates energy by fusing hydrogen into helium in its core.

-The core temperature is 10 million K.

-The convection zone is cooler than the radiation zone.

-The composition of the photosphere is the same as that of the gas cloud that gave birth to our solar system.

One statement about the Sun from Part A is "The corona is hotter than the photosphere." Which of the following statements provides observational evidence for this claim?

The corona primarily emits X rays while the photosphere primarily emits visible light.

Now consider the statements in Part A that are inferred from models. A solar model is used to calculate interior conditions based on certain "known" characteristics of the Sun, such the Sun's total mass. How do we know the Sun's mass?

We can calculate it by applying Newton's version of Kepler's third law with Earth's orbital period (1 year) and Earth's average distance from the Sun (1 AU).

A solar model is used to calculate the expected temperature and density at all depths within the Sun. These results are then used to calculate the expected fusion rate within the Sun. We have confidence that the model is correct because it agrees with the observed characteristics of the Sun. Which of the following observations can be used to check that we really do know the Sun's internal fusion rate?

-Observations of neutrinos coming from the Sun -Measurements of the Sun's total energy output into space

Listed following are events or phenomena that occur during either the part of the sunspot cycle known as solar minimum or the part known as solar maximum. Match these items to the correct part of the sunspot cycle.

Solar maximum:

-auroras are most likely in Earth's skies

-occurs about 11 years after a solar maximum (on average)

-sunspots are most numerous on the Sun

-orbiting satellites are most at risk

solar flares are most common

Solar minimum:

-occurs about 5 to 6 years after a solar maximum (on average)

What is the overall fusion reaction that converts mass into other forms of energy in the Sun's core?

4 hydrogen nuclei become 1 helium nucleus

When we refer to the solar thermostat, we are referring to the idea that __________.

the Sun's core temperature naturally stays stable

The energy balance that contributes to the solar thermostat is a balance between __________.

the energy released in the core by fusion and the energy radiated from the Sun's surface into space

Which of the following changes would cause the fusion rate in the Sun's core to increase?

-a decrease in the core radius

-an increase in the core temperature

Which of the following must occur for a star's core to reach equilibrium after an initial change in fusion rate?

-If the fusion rate initially increases, then the core expands. -If the fusion rate initially decreases, then the core contracts.

What would happen if the fusion rate in the core of the Sun were increased but the core could not expand?

The Sun's core would start to heat up, and the rate of fusion would increase even more.