Chapter 14

What is the most common kind of element in the solar wind?

Hydrogen

Does the sun's fusion rate remain steady or vary widely? Describe the feedback process that regulates the fusion rate.

It increases very slowly over time, being about 30% smaller 4.5 billion years ago. The Sun is in hydrostatic equilibrium between gravity that pulls inwards and increases the temperature and pressure and the radiation pressure that pushes outward. The fusion rate is vary sensitive on temperature. An increase of T would increase the fusion rate, increase the radiation pressure and expand the core, which then reduces the temperature again

Solar Maximum

-sunspots are most numerous on the sun -solar flares most common -occurs about 11 years after another, maximum (on avrg)

The overall result of the proton-proton chain is that __________.

4 H becomes 1 He + energy p -> He⁴ + Energy Energy =(2positrons+2photons+2neutrino)

According to modern science, approximately how old is the Sun?

4.5 billion y/o

Solar minimum

5-6 years after a solar maximum

Explain how mathematical models allow us to predict conditions inside the sun

A model uses he Sun's observed composition and mass as inputs to equations that describe gravitational equilibrium, the solar thermostat, and the rate at which solar energy moves from the core to photosphere. Can predict the sun's temp, pressure, and density and nuclear fusion at the core.

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

An increase in the core temperature A decrease in the core radius

At the center of the Sun, fusion converts hydrogen into?

Helium, energy and neutrinos.

Which of these things poses the greatest hazard to communication satellites?

Protons from the sun

What do we mean by solar activity? Describe some of the features of solar activity, including sunspots, solar prominences, solar flares, and coronal mass ejections.

Solar activity refers to the changing features of the Sun such as sunspots, flares, prominences, and coronal mass ejections. The sunspots are regions of the photosphere that are cooler than the surrounding plasma so that they appear darker. The sunspots occur in pairs with the magnetic field lines arcing from one sunspot to the other. Where gas from the chromosphere or corona becomes trapped in the magnetic field, we see prominences. Flares are intense storms that result in bursts of X rays and fast-moving charged particles being shot off into space. Coronal mass ejections are huge bubbles of energy, charged particles that are released from the Sun's corona.

If the Sun's magnetic field somehow disappeared, would there would be no more sunspots on the Sun?

Sunspots are regions of strong magnetic fields, so with no magnetic field there would be no sunspots.

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

Describe the appearance and temperature of the Sun's photosphere. Why does the surface look mottled? How are sunspots different from the surrounding photosphere?

The Sun's photosphere is at a temperature of 5,800 K. It looks mottled because it is churning constantly with rising and falling gas. However, in some areas the surface is cooler and therefore less bright. These areas are sunspots, where the temperature is "only" 4,000 K

Why are the chromosphere and corona best viewed with ultraviolet and x-ray telescopes, respectively? Briefly explain how we think the chromosphere and corona are heated.

The density in them is so low that we can't see the gas with visible light, except during a total eclipse. We can observe them using x-ray and ultraviolet telescopes though. This is due to the high temperatures. The heating of the corona and chromosphere is believed to be caused by the convection of gas, this convection shakes the magnetic field lines and energy is carried up them into the solar atmosphere where the energy is released as heat.

Describe the leading model for explaining the sunspot cycle. Does the sunspot cycle influence Earth's climate? Explain?

The field lines (which are strengthened by convection) get contorted by the Sun's rotation, which is faster at the equator. They cause more sunspots and other activity as they contort and then they eventually reset and solar activity becomes rarer. It is debated whether or not solar activity affects the climate, there are some patterns but it is unclear how great the effect is.

What is the sunspot cycle? Why is it sometimes described as an 11-year cycle and a 22-year cycle? Are there long term changes in solar activity?

The sunspot cycle is a cycle in which the average number of sunspots per year gradually rises and falls, 11 years between maximums and minimums (22 per cycle.) There have been times when there are almost no sunspots, indicating that the long term changes can possibly be very drastic.

How do magnetic fields keep sunspots cooler than the surrounding plasma? Explain.

They separate the sunspot's gas from the rest of the Sun's surface gas. This prevents them from mixing and heating the sunspot back to the average surface temperature.

Which of the following correctly describes how the process of gravitational contraction can make a star hot? Why is it important in the Sun's History?

When a star contracts in size, gravitational potential energy is converted to thermal energy. This theory would mean the earth is 25 million years old but fossil evidence indicates this is not true.

How does the number of neutrinos passing through your body at night compare with the number passing through your body during the day?

about the same

sunspots:

appear as dark blotches on the sun's surface

strong force

binds protons and neutrons together in atomic nuclei the only force in nature that can overcome the electromagnetic repulsion btwn two positive charged nuclei

Most of the sun's UV light is emitted from the narrow layer called the ___ where the temp increases with altitude

chromosphere

We can see the sun's ___ most easily during a solar eclipse.

chromosphere

Energy moves through the sun's _____ by means of rising hot gas anfalling of cooler gas.

convection zone

From center outward, which of the following lists the "layers" of the Sun in the correct order?

core, radiation zone, convection zone, photosphere, chromosphere, corona

Which of the following layers of the Sun can be seen with some type of telescope?

corona, photosphere, chromosphere

convection zone:

energy generated in the solar core travels upward, transported by the rising of hot gas and falling of cool gas, has the sun's churning appearance

What two physical processes balance each other to create the condition known as gravitational equilibrium in stars?

gravitational force and outward pressure

nuclear fusion:

how the sun's energy is made: combining

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.

photosphere

lower layer of the sun's atmosphere, visible surface of the sun, consists of gas far less dense than our atmosphere only 6,000K where you'll find sunspots, intense magnetic fields

chromosphere

only 10,000K, middle layer of the sun's atmosphere and emits most of the sun's UV light

corona:

outter most layer about 1 million K emits most of the sun's x-rays

nearly all visible light we see from the sun is emitted from the

photosphere

core:

source of sun's energy, nuclear fusion transforming hydrogen to helium 15 million K

nuclear fission:

the process of splitting an atomic nucleus

Power is

the rate at which energy is being used or released

Energy balance in the Sun refers to a balance between _________.

the rate at which fusion generates energy in the Sun's core and the rate at which the Sun's surface radiates energy into space

solar wind:

the stream of charged particles continually blown outward in all directions from the sun helps shape the magnetosphere of planets, and blows back the material that forms the plasma tails of comets

luminosity is

the sun's total power output

To estimate the central temperature of the Sun, scientists _________

use computer models to predict interior conditions

What are the appropriate units for the Sun's luminosity?

watts

a sudden temp rise in the suns core is nothing to worry about because conditions in the core will soon return to normal. Explain

when the temp rises in the suns core, the molecules in there start to move faster and build up higher temps. To accommodate for this the sun expands until the molecules slow down from less pressure and eventually bring back the sun to stasis

radiative zone

where energy moves outward primarily in the form of photons of light temp: 10 million K

What are nuetrinos? What is the solar nuetrino problem?

Neutrinos are subatomic particles produced in nuclear reactions. They move at nearly the speed of light and almost never interact with matter. Detectors on Earth found only about 1/3 of the neutrinos predicted by models of nuclear fusion in the Sun. This disagreement between theory and data was called "the solar neutrino problem." Today, we think we have solved the problem and that the electron neutrinos we were measuring had changed into other kinds of neutrinos. Recent experiments support this idea by showing that neutrinos can change their type. Other experiments are showing that the total number of neutrinos of all types is about what the models for fusion in the Sun predict, indicating that the problem is solved.

The source of energy that keeps the Sun shining today is _________.

Nuclear Fusion

What is the difference between nuclear fission and nuclear fusion? Which one is used for nuclear power plants? Which one does the sun use?

Nuclear fusion and nuclear fission are two different types of energy-releasing reactions in which energy is released from high-powered atomic bonds between the particles within the nucleus. The main difference between these two processes is that fission is the splitting of an atom into two or more smaller ones while fusion is the fusing of two or more smaller atoms into a larger one. Nuclear fission is used for nuclear power plants. Nuclear fusion is used by the sun.

Why does nuclear fusion require high temperatures and pressures?

Nuclear fusion requires high temperatures to keep the protons colliding at high enough speeds that they can get close enough to stick together rather than be deflected by the electromagnetic force. The high pressure, generated by the weight of all the Sun's layers above the core, is required to keep the hot gas in the Sun's core from exploding into space, shutting off the nuclear reactions. A high particle density is required to sustain a high rate of fusion.