Chapter 18 Astronomy Vocabulary

Front 1

22-year solar cycle

Back 1

The semiregular interval between successive appearances of sunspots at the same latitude with the same magnetic polarity.

Front 2

Chromospheres

Back 2

a layer in the atmosphere of the Sun between the photosphere and the corona

Front 3

CNO cycle

Back 3

a series of nuclear reactions in which carbon is used as a catalyst to transform hydrogen into helium

Front 4

conduction

Back 4

the transfer of heat by directly passing energy from atom to atom

Front 5

convection

Back 5

the transfer of energy by moving currents of fluid or gas containing that energy.

Front 6

convective zone

Back 6

the region in a star where convection is the dominant means of energy transport

Front 7

corona

Back 7

the sun's outer atmosphere, which has a high temperature and a low density

Front 8

coronal hole

Back 8

a region in the sun's corona that is deficient in hot gases

Front 9

coronal mass ejection

Back 9

an event in which billions of tons of gas from the sun's corona is suddenly blasted into space at a high speed.

Front 10

differential rotation

Back 10

the rotation of a nonrigid object in which parts adjacent to each other at given times do not always stay close together.

Front 11

filament

Back 11

a portion of the sun's chromosphere that arches ito high altitudes

Front 12

granulation

Back 12

the rice grain-like structure found in the solar photosphere

Front 13

granule

Back 13

a convective cell in the solar photosphere

Front 14

helioseismology

Back 14

the study of the vibrations of the Sun as a whole

Front 15

hydrogen burning

Back 15

the thermonuclear conversion of hydrogen to helium

Front 16

hydrostatic equilibrium

Back 16

the balance between the weight of a layer in a star and the pressure that supports it

Front 17

limb darkening

Back 17

the phenomenon whereby the sun looks darker near its apparent edge, or limb, than near the center of its disk

Front 18

luminosity

Back 18

the rate at which electromagnetic radiation is emitted from a star of other object

Front 19

magnetic-dynamo model

Back 19

a theory that explains the solar cycle as a result of the sun's differential rotation acting on the sun's magnetic field

Front 20

magnetogram

Back 20

an artificial pic of the sun that shows regions of different magnetic polarity

Front 21

negatice hydrogen ion

Back 21

a hydrogen atom that has acquired a second electron

Front 22

neutrino

Back 22

a subatomic particle with no electric charge and little or no mass, yet one that is important in many nuclear reaction

Front 23

photosphere

Back 23

the region in the solar stmosphere from which most of the visible light excapes into space

Front 24

plage

Back 24

a bright region in the solar atmosphere as observed in the monochromatic light of a spectral line

Front 25

plasma

Back 25

a hot ionized gas

Front 26

positron

Back 26

an electron with a positice rather than negative elctric charge; the antiparticle of the electron

Front 27

prominence

Back 27

flamelike protrusions seen near the limb of the Sun and extending into the solar corona

Front 28

proton-proton chain

Back 28

a sequence of thermonuclear reactions by which hydrogen nuclei are build up into helium nuclei

Front 29

radiative diffusion

Back 29

the random migration of phrotons from a star's center toward its surface

Front 30

solar neutrino

Back 30

a neutrino emitted from the core of the sun

Front 31

solar neutrino problem

Back 31

the discrepancey between the predicted and observed numbers of solar neutrinos

Front 32

solar wind

Back 32

an outward slow of particles (mostly electrons and protons)from the sun

Front 33

spicule

Back 33

a narrow jet of rising gas in the solar chromosphere

Front 34

sunspot

Back 34

a temporary cool region in the solar photosphere

Front 35

sunspot cycle

Back 35

the semiregular 11-year poeriod with which the number of sunspots fluctuates

Front 36

sunspot max/ min

Back 36

that time during the sunspot cycle when the number of sunspots is highest/ lowest

Front 37

supergranule

Back 37

a large convective feature of the solar atmisphere, ususally outlined by spicules

Front 38

thermal equilibrium

Back 38

a balance between the input and outlow of heat in a system

Front 39

thermonuclear fusion

Back 39

the combining of nuclei under condistions of high temperature that releases substantial energy

Front 40

zeeman effect

Back 40

a splitting or broadening of spectral lines due to a magnetic field.

Front 41

radiative zone

Back 41

a region within a star where radiative diffusion is the dominant mode of energy transport

Front 42

solar flare

Back 42

a sudden, temporary outburst of light from an extended region of the solar surface.