Chapter 15: The Sun: A Garden-Variety Star

Comprehensive vocabulary flashcards covering the structure, atmospheric layers, magnetic cycle, activity, and space weather phenomena associated with the Sun.

Solar Core

The innermost $20\%$ of the Sun's interior that serves as the source of all the Sun's energy.

Which zones bring energy to the surface?

Radioactive and Convection zone

Plasma

A state of matter consisting of fully ionized gas, which constitutes the interior and atmosphere of the Sun due to extreme temperatures.

Outer Layers of the sun

Photosphere, Chromosphere, Corona

Photosphere

The Sun's apparent visible 'surface' layer that separates the interior from the exterior layers, emitting visible light with a blackbody temperature of approximately $5800\,\text{K}$.

Granulation

A fine-scale mottled pattern visible across the solar photosphere produced by underlying convection cells where hot material rises and cooler material sinks.

Chromosphere

The atmospheric layer above the photosphere that is visible only during solar eclipse. emits near-ultraviolet light and is visible as a pink or reddish ring

Spicules

Small, bright reddish spikes or whisker-like jets of gas located in the chromosphere seen projecting along the limb of the solar disk.

Transition Region

The narrow boundary layer in the solar atmosphere between the chromosphere and the corona where temperature experiences a rapid, dramatic increase instead of decreasing with distance from the core.

Corona

The Sun's outermost extended atmospheric layer, reaching temperatures of over $1\,\text{million}$ degrees and best observed in extreme ultraviolet and X-rays. It is where we find active regions and coronal holes

Sunspots

Dark, relatively cooler regions on the solar photosphere caused by concentrated magnetic fields that inhibit the upward convective flow of hot plasma.

Solar Cycle

An approximately $11\text{-year}$ recurring cycle in which the Sun's magnetic field becomes progressively wound by differential rotation, snaps, resets, and modulates the number of sunspots and overall solar activity.

Butterfly Diagram

A latitude-versus-time plot tracking daily sunspot area that illustrates the cyclical migration of sunspots toward the equator over each $11\text{-year}$ solar cycle.

Active Regions

Bright, magnetically intense areas in the solar corona that align with sunspot groups in the photosphere beneath them and serve as launch sites for solar flares and coronal mass ejections.

Solar Flare

A sudden release of energy in an active region caused by changing magnetic fields that emits high-energy photons, predominantly X-rays.

Coronal Mass Ejection (CME)

A major solar event where a massive burst of magnetized physical plasma is released and ejected from the corona into interplanetary space.

Coronal Holes

Dark regions observed in ultraviolet images of the corona where magnetic field lines extend openly into interplanetary space, resulting in reduced plasma density and serving as the primary source of the fast solar wind.

Solar Wind

A continuous outflow of charged particles accelerated away from coronal holes along open magnetic field lines throughout the solar system.

Space Weather

Variable conditions and disturbances in the space environment driven by solar activity (including flares, CMEs, and the solar wind) that can interact with and influence the Earth.

Aurora

Atmospheric light displays (such as Aurora Borealis in the north and Aurora Australis in the south) produced when electrons from the solar wind or CMEs are guided toward Earth's magnetic poles and collide with atmospheric gases.

Richard Carrington

The English amateur astronomer who documented an intense solar flare event in 1859 that was followed days later by low-latitude aurorae and extensive telegraph network failures.