Interstellar Matter

This set of flashcards covers key concepts related to interstellar matter, including definitions and descriptions of various types of gas, dust, and observational phenomena.

Interstellar Matter

The matter that exists in the space between stars, primarily consisting of gas and dust.

Gas and Dust

The two primary types of interstellar matter; gas is mainly interstellar gas, while dust consists of tiny solid particles.

Molecular Clouds

Cold, dense clouds in interstellar space predominantly made of hydrogen molecules (H2).

H II Regions

Areas of emission nebulae where atoms are mostly ionized, found near hot O and B stars.

21-cm Line

A spectral line emitted by neutral hydrogen atoms (H I) that is crucial for radio observations of interstellar gas.

Emission Nebulae

Regions of space where gas is ionized, typically found around hot stars that emit UV light, leading to recombination of electrons.

Recombination

The process where free electrons combine with protons to form neutral hydrogen, emitting photons in the process.

Interstellar Absorption Lines

Wavelengths at which cool clouds absorb light from background stars, providing information about those clouds.

Cold Molecular Clouds

Dense clouds characterized by low temperatures (around 10 K) that can serve as nurseries for new stars.

Photons

Particles of light that are emitted or absorbed during the processes of recombination or transitions in atomic states.