Discovering the Essential Universe: Chapter 9

What do astronomers mean by a "model of the Sun"?

"A model of the Sun" is a set of mathematical equations that govern the behavior of matter, energy & their solution using the parameters relevant to the Sun.

Name & describe seven features of the active Sun. Which two are the same, seen from the angles?

1. sunspots 2. plages 3. flares 4. filaments 5. prominences 6. coronal holes 7. coronal mass ejections Filaments & prominences are the same feature seen from different angles.

What is a neutrino, & why are astronomers so interested in detecting neutrinos from the Sun?

A subatomic particle, w/ no electric charge & little mass. When astronomers detect neutrinos from the Sun they are coming directly from the core & are the only direct core observations possible.

Give an everyday example of hydrostatic equilibrium not presented in the book.

An inflated balloon will expand until it pops

Why is the solar cycle said to have a period of 22 years, even though the sunspot cycle is only 11 years long?

Because there is two of the sunspot cycles.

Describe the three main layers of the solar atmosphere & how you would best observe them.

Photosphere -> normally visible surface of the Sun & can be observed with visible light. Chromosphere & Corona -> best observed during total eclipses or artificial eclipses produced by coronagraphs.

Describe the dangers in attempting to observe the Sun. How have astronomers learned to circumvent these hazards?

The danger comes from ultraviolet light that can cause permanent eye damage. Astronomers advise people to use dark shades while attempting to observe the Sun.

Describe the suns interior. Include references to main physical processes that occur at various depths within the sun.

The hottest & densest part of the Sun is the core when hydrogen fusion is occurring. Surrounding the core is the radiative zone where energy from the core is moving upward by radiative transport. Surrounding the radiative zone is the convective zone where huge updrafts of matter carry heat to the surface.

How do astronomers detect the presence of a magnetic field in hot gases, such as the field in the solar atmosphere?

The magnetic field produces lines and the lines are visible

Describe the features of the Sun's atmosphere that are always present.

The photosphere, the chromosphere, & the corona.

Give an everyday example of heat transfer by convection & radiative transport.

The radiant heat from a fireplace warms the occupants of the room.

What is hydrogen fusion? This process is sometimes called "hydrogen burning." How is hydrogen burning fundamentally unlike the burning of a log in a fireplace?

The thermonuclear fusion of hydrogen to produce helium. This is incorrectly referred to as hydrogen burning because hydrogen is the fuel. The burning of a log is a chemical reaction, whereas hydrogen fusion is a nuclear reaction.

Describe the three main layers of the Sun's interior.

The three main layers are: 1. the core -> where the energy is generated 2. radiative zone -> where energy is transported upward 3. convective zone -> where convection carries the energy to the surface.

Why do thermonuclear reactions in the Sun take place only in its core?

Thermonuclear reactions require a temperature of 10 million K. Only the Sun's core has this temperature.