Astronomy Chapter 14 Vocab

Front 1

bipolar flows

Back 1

Narrow columns of high-speed gas ejected by a protostar in two opposite directions.

Front 2

Bok globule

Back 2

Small, dark, interstellar cloud, often approximately spherical; many of them are the early stages of protostars.

Front 3

degenerate gas

Back 3

An extremely dense gas in which the electrons and nuclei are tightly packed, its pressure does not depend on its temperature.

Front 4

deuterium

Back 4

A form of hydrogen in which the nucleus contains a neutron in addition to a proton, sometimes called "heavy hydrogen."

Front 5

helium flash

Back 5

The beginning of helium fusion in a low mass star.

Front 6

instability strip

Back 6

A region in the HR diagram indicating stars that pulsate.

Front 7

interstellar cloud

Back 7

A cloud of gas and dust in between the stars.

Front 8

main-sequence lifetime

Back 8

The time a star remains a main-sequence star, fusing hydrogen into helium in its core.

Front 9

nucleosynthesis

Back 9

The formation of elements, generally by the fusion of lighter elements into heavier ones.

Front 10

period-luminosity relation

Back 10

A law stating that the longer the period of a pulsating variable star, the more luminous it is.

Front 11

planetary nebulas

Back 11

A shell of gas ejected by a low mass star late in its evolutionary lifetime.

Front 12

protostar

Back 12

A star still in its formation stage, heated by gravitational contraction.

Front 13

red giant

Back 13

A cool, luminous star whose radius is much larger than the Sun's.

Front 14

shell source

Back 14

A region in a star where the nuclear energy generation occurs around the core rather than in it.

Front 15

supernova

Back 15

An explosion that occurs at the end of some stars' evolution.

Front 16

supernova remnant

Back 16

The debris ejected from a star when it explodes as a supernova.

Front 17

triple alpha process

Back 17

The fusion of three helium nuclei (alpha particles) into a carbon nucleus, this process is sometimes called helium burning and it occurs in many old stars.

Front 18

T Tauri stars

Back 18

A type of extremely young star that varies erratically in its light output.

Front 19

turnoff point

Back 19

The location on the main sequence where a star's evolution causes it to move away from the main sequence toward the red giant region.

Front 20

variable star

Back 20

A star whose luminosity changes over time.