Sun and Star Formation

Astronomy

Solar wind.

The corona extends several million kilometers and gradually becomes the...

The helium stays in the core, and the energy is in the form of gamma rays which gradually lose their energy as they travel out the core and emerge as visible light?

What actually occurs during this reaction? 4(1H)→ $He + energy + 2 neutrinos

When magnetic field lines are distorted by Sun's differential rotation.

When do sunspots form?

They are slightly cooler than their surroundings.

Why do sunspots appear dark?

The Sun has an 11 year sunspot cycle, during which sunspot numbers rise and fall, and are at a maximum every 11 years. Really 22 years, because the sunspots switch polarities between the northern and southern hemispheres every 11 years.

Describe the sun spot cycle.

Solar prominence.

Solar _________ is a large sheet of ejected gas.

List and describe the four Fundamental Forces in Nature

Gravity: Very weak, but always attractive and infinite in range.

Electromagnetic: much stronger than gravity, but either attractive or repulsive, infinite range.

Weak nuclear force: responsible for beta decay; short in range (1-2 proton diameters); weak.

Strong Nuclear Force: Keeps nucleus together; short range; very strong.

“Sphere of light.” The light we see as the surface of the Sun.

The word photosphere means...

"Sphere of color".

The word chromosphere means...

The lower layer.

What part of the Sun's atmosphere can only be seen during a total solar eclipse?

73.4% Hydrogen and 24% Helium.

What elements make up the Sun's interior in what percentages?

The core.

Nuclear fusion takes place in what part of the Sun?

The Radiation Zone.

What is the source of the Sun's energy?

The differences in mass.

Where does the energy come from in a nuclear reaction?

Albert Einstein.

Who developed the famous equation E=mc^2?

Like- charged nuclei have to get close enough to each other to fuse; this can only happen if temperatures get extremely high

Nuclear fusion can only happen under what conditions?

5 billion years.

The Sun has enough hydrogen left to continue fusion for how much longer?

Gravitational

Hydrogen Fusion

Expanding

Contracting

Hydrostatic equilibrium, inward ____________ force must be balanced by outward pressure from the _________ _____________ reaction: This means that the Sun is not ___________ nor ____________ at this time.

Chromosphere

The lower layer of the Sun's atmosphere that is just above the photosphere. It is cooler and can only be seen during a solar eclipse. Small storms in this area emit spicules.

Convection

The transfer of energy by the motion of a fluid.

Convection Zone

The layer just under the surface of the Sun where energy is transferred by convection.

Corona

Outermost layer of the Sun's atmosphere that extends serval million kilometers and gradually becomes solar wind.

Luminosity

Total energy radiated by the Sun- can be calculated from the fraction of that energy that reaches earth.

Nuclear Fusion

The combining of two or more small atomic nuclei into a larger atomic nuclei.

Radiation

Energy that is radiated or transmitted in the form of electromagnetic rays or waves or particles.

Radiation Zone

The core of the Sun where energy is transferred by radiation.

Solar Wind

High speed charged particles (protons and electrons) that are constantly escaping the Sun and flow throughout the solar system.

Star formation is ongoing. Star forming regions are seen in our galaxy as well as others.

When does star formation occur and where?

Contract

Gravitational

Nuclear Fusion

Star formation happens when part of a dust cloud (nebulae) begins to __________ under its own_______________ force. It then collapses and the center becomes hotter and hotter until _________ _______ begins in the core.

Shock

Star Clustering

Interstellar cloud starts to contract, probably triggered by a _________________ wave or pressure wave from a nearby star. When __________ __________ begins. The protostar finally becomes a star.

Not enough mass.

Why are some protostars unable to fuse hydrogen?

An open cluster (young star cluster).

Pleiades is an example of...

Brown Dwarf

A protostar that does not have enough mass to fuse hydrogen, so it cools down and is left as a planet

Closed Star Clusters (Globular Clusters)

Old, very large, and spherical.

Hydrostatic Equilibrium

Inward gravitational force must be balanced by outward pressure from the hydrogen fusion reaction: this means the Sun is not expanding nor contracting at this time.

Open Star Clusters

Relatively young, small, and randomly shaped.

Protostar

A contracting cloud of gas and dust with enough mass to form a star; earliest stage in a star's life.

Main Sequence Star

A young star that has enough mass and pressure to fuse hydrogen.

Red Giant Star

A large star that results from the shortage of hydrogen; fuses to helium and other elements.

White Dwarf

Form from Red Giants. Small, dense, dying star that is rich in carbon and oxygen because it only fuses to carbon and oxygen.

Small mass stars.

Black Dwarf

Form from Red Giants. A dead star that gives off all energy and cools off.

Small mass stars.

Neutron Star

A star that has collapsed under gravity to the point that the electrons and protons have smashed together to form neutrons; formed after a supernova.

Nebula

A huge cloud of gas and dust; mostly hydrogen.

Balck Hole

Result of a Red Giant. Star so massive that light cannot escape and collapses in on itself.

Large mass stars.

Its mass

What is the most important characteristic that determines the way a star moves through its life cycle?

Supernova

The explosion of a star that happens after it can no longer fuse elements in the core.