Astrophysics (Index)About

interstellar medium

(matter within a galaxy between star systems)

The interstellar medium (ISM) is matter such as gas and dust between stars. (Matter between entire galaxies is called the intergalactic medium.) Depending upon circumstance, the gas may be ionized, neutral, or molecular. Density varies from as little as 1 per 10,000 cm3 to 1,000,000 per cm3 (compared to about 2.5×1019 per cm3 for dry air at sea level). The ISM's existence was first deduced through observed absorption lines.

There is a nesting of types of ISM:

A diffuse interstellar band (DIB) is an absorption spectral band affecting observations of stars and other objects. Such bands are attributed to polycyclic aromatic hydrocarbons in the ISM.

Further reading:

Referenced by pages:
bipolar outflow
bow shock
methylidyne (CH)
infrared cirrus
cold gas
cosmic dust
dark matter halo
dense core mass function (DCMF)
diffuse interstellar bands (DIBs)
dispersion measure (DM)
diffractive interstellar scintillation (DISS)
extragalactic background light (EBL)
extreme ultraviolet (EUV)
star formation feedback
fast radio burst (FRB)
galactic electron density
glycine (Gly)
helium 1083 nm line
Herbig-Haro object (HH)
homologous collapse
hydrogen (H)
ionization correction factor (ICF)
intergalactic medium (IGM)
Interstellar Medium Absorption Profile Spectrograph (IMAPS)
interstellar holography
ionizing radiation
interplanetary medium (IPM)
lithium (Li)
magnetic field
mass density
magnetohydrodynamics (MHD)
plasma frequency
pulsar (PSR)
pulsar wind nebula (PWN)
refractive interstellar scintillation (RISS)
RT instability
Sloan Digital Sky Survey (SDSS)
shock wave
submillimeter galaxy (SMG)
supernova remnant (SNR)
solar wind
Zwicky 3146 (Zw 3146)