Astrophysics (Index)About

state of ionization

(ionization)
(difference in an ion's electron count versus proton count)

An ion is an atom or molecule that has more or less electrons than protons, as opposed to a neutral atom in which the numbers match. The term state of ionization (or, more briefly, just ionization) is used to characterize this surplus or deficit, such as +2 for "missing two electrons". In such a case, fully ionized means missing all the electrons, and ground state means missing none. In astrophysics, the following terminology is often used: the chemical symbol followed by I means neutral, II means singly ionized, III for doubly ionized, etc., e.g., CI, CII, CIII for carbon at these three states of ionization. The more common symbol in other sciences is (e.g., for hydrogen), H+ for singly ionized, H++ for doubly ionized, etc.


In context, state of ionization (and the term fully ionized) may be used to mean the degree of ionization, referring to a number of atoms, characterizing how many are ions and how many are at each state. For a collection of atoms/molecules, e.g., a gas, the percentages of the gas at each state of ionization is of interest, because of its relation to temperature and to the production of the spectral lines, allowing the study of spectral lines to be used to determine temperature, through the Saha equation.


The term ionization has been used metaphorically in the study of multiple star systems (e.g., binary stars), to indicate the escape of one of the companions.


(physics,quantum mechanics,atoms,ionization)
Further reading:
https://en.wikipedia.org/wiki/Ionization
https://en.wikipedia.org/wiki/Chemical_symbol#Extension_of_the_symbol
https://www.pas.rochester.edu/~blackman/ast104/ionization.html

Referenced by pages:
absorption
air shower
anomalous cosmic rays (ACR)
ARGOS
asymptotic giant branch (AGB)
atomic number (Z)
aurora
Baldwin effect
Balmer jump (BJ)
binding energy
Boltzmann equation
BPT diagram
calcium (Ca)
carbon (C)
circumstellar envelope (CSE)
cold gas
comet
CONCERTO
continuous absorption
continuum emission
cooling function
Cryogenic Dark Matter Search (CDMS)
dark age
degree of ionization
diffractive interstellar scintillation (DISS)
dynamo
electron (e-)
electron pressure
electron volt (eV)
electrostatic barrier
energetic neutral atom (ENA)
epoch of reionization (EOR)
escape fraction
fine structure
forbidden line
Fraunhofer lines
galactic electron density
gas pixel detector (GPD)
helium 1083 nm line
HI region (HI)
HII region (HII)
HZE ion
IMAGE­
instability strip
interstellar medium (ISM)
ion
ion engine
ionization correction factor (ICF)
ionization fraction
ionization potential
ionized carbon fine structure line ([CII])
ionized hydrogen (HII)
ionizing radiation
ionosphere
iron (Fe)
IXPE
K-line
kappa mechanism (κ-mechanism)
Kramers opacity law
LINER
Lorentz force
Lyman series (L)
Lyman-alpha forest
magnetorotational instability (MRI)
mass spectrometer
microwave
Millimeter-wave Intensity Mapping Experiment (mmIME)
molecular hydrogen dissociation front (H2 dissociation front)
nitrite (NO2-)
nitrogen (N)
O-type star (O)
oscillator strength
partial ionization zone
photodisintegration
photoionization
photosphere
planetary nebula (PN)
plasma
plasma astrophysics
plasma frequency
potential energy (PE)
proportional counter
protoplanetary disk (PPD)
protoplanetary nebula (PPN)
recombination
refractive interstellar scintillation (RISS)
Rydberg constant (RH)
Rydberg unit
Saha equation
solar storm
spectral class
spectral line
spectral line designation
star formation feedback
star formation rate (SFR)
Stark effect
Strömgren sphere
sulfur (S)
supernova (SN)
temperature
The Survey for Ionization in Neutral Gas Galaxies (SINGG)
Thomson optical depth (τT)
Tomographic Ionized-carbon Mapping Experiment (TIME)
transition region
Wilson-Bappu effect
Z+

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