Astrophysics (Index)About

infrared

(IR, infrared light, infrared radiation)
(light with wavelength too long for our eyes to sense)

Infrared (IR or infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light and shorter than that of radio waves. Cited wavelength ranges vary somewhat: a representative example is 750 nm to 1 mm, corresponding to EMR frequencies between 300 GHz and 400 THz. Portions of its wavelength-span are blocked by Earth atmosphere and infrared bands defined for astronomical use are aligned with the intervening atmospheric windows and identified by the same alphabetic codes:

infrared portion wavelengths band/window
near infrared (NIR)650-1000 nmR band and I band
near infrared1100-1400 nmJ band
near infrared1500-1800 nmH band
near infrared2000-2400 nmK band
near infrared3000-4000 nmL band
near infrared4600-5000 nmM band
mid infrared (MIR)7500-14500 nmN band
mid infrared17-25 μmQ band
far infrared (FIR)28-40 μmZ band
far infrared330-370 μmZ band
(far infrared)450 μmsubmillimeter

Some near-infrared observations are made through visible-light telescopes, whose mirrors are suitable for adjacent portions of the spectrum. The shortest-wavelength infrared telescopes (submillimeter) are more like radio telescopes and similar interferometry is of use. IR is often used to detect temperature at a distance, because virtually anything with a temperature less than ~3800 K emits black-body radiation peaking in infrared (thermal IR) and the temperature can be determined (in principle) by Wien's displacement law. IR is also used for sensing "through walls" because some material that is opaque to visible light is transparent to IR. IR sensors are used in the study of planets from space probes: e.g., IR cameras or spectrographs. Infrared luminosity (LIR or LIR), an object's luminosity in the infrared is of interest, often indicating intervening obscuring gas and dust, heated so as to produce an infrared thermal radiation.

Infrared astronomy can view virtually anything producing thermal radiation, but is especially useful for objects whose EMR arrives within the infrared range. Prominent are M-type stars which are dim outside the infrared, and many objects at cosmological distances, whose spectra are redshifted into the infrared, motivating efforts such as the James Webb Space Telescope (JWST).


(EMR,spectrum,band)
Further reading:
https://en.wikipedia.org/wiki/Infrared
https://en.wikipedia.org/wiki/Infrared_astronomy
https://en.wikipedia.org/wiki/List_of_largest_infrared_telescopes
http://hyperphysics.phy-astr.gsu.edu/hbase/ems3.html
https://astronomy.swin.edu.au/cosmos/i/Infrared
https://www.daviddarling.info/encyclopedia/I/infrared_astronomy.html
http://scipp.ucsc.edu/~tesla/lecture5.pdf
WaveLFreqPhoton
Energy
  
750nm400THz1.7eVbegininfrared
1mm300GHz1.3meVendinfrared
PrefixExample  
IRSIRS 5IR source

Referenced by pages:
A-LIST
active galactic nucleus (AGN)
active galaxy
AFGL Four Color Infrared Sky Survey (AFGL)
Air-SPEC
AKARI
aperture synthesis
APOGEE
ARIEL
ASPIRE
Atacama Submillimeter Telescope Experiment (ASTE)
atmospheric window
black hole shadow
black-body radiation
Brackett series
Canada-France-Hawaii Telescope (CFHT)
Cassini
Catalog of Infrared Observations (CIO)
CFBDS
circumstellar disk
Cosmic Background Explorer (COBE)
cosmic background radiation (CBR)
cosmic dust
cosmic infrared background (CIB)
cosmic optical background (COB)
CRIRES
Cygnus-X
dark nebula
Darwin
Dawn
DISCOVR
dust echo
dusty galaxy
electromagnetic radiation (EMR)
electromagnetic spectrum
EnVision
ESO 3.6m Telescope
Euclid
European Southern Observatory (ESO)
European Southern Observatory Very Large Telescope (ESO VLT)
extreme adaptive optics (ExAO)
extremely red object (ERO)
Fabry-Pérot interferometer (FPI)
Faint Infrared Grism Survey (FIGS)
far infrared (FIR)
filter
FINESSE
fluorescence
Fred Lawrence Whipple Observatory (FLWO)
Galileo Observatory
Gamow Explorer
Gattini-IR
Gemini Observatory
Gemini Planet Imager (GPI)
GI2T
Giant Magellan Telescope (GMT)
Gran Telescopio Canarias (GTC)
grating
greenhouse effect
griz photometric system
Hale Telescope
Hayabusa2
HD1
Herbig AeBe star (HAeBe)
HERMES
Herschel Space Observatory
Hiltner Telescope
Hope Probe
Hubble Deep Field South (HDF-S)
Hubble Space Telescope (HST)
Humphreys series
hyperluminous infrared galaxy (HLIRG)
I band
immersion grating
infrared cirrus
infrared dark cloud (IRDC)
infrared excess (IRX)
infrared source (IRS)
Infrared Space Observatory (ISO)
Infrared Survey Facility (IRSF)
Infrared Telescope Maffei (ITM)
interferometer
IOTA
IPAC
IRAC Shallow Survey (ISS)
IRAS
IRSA
IRTF
IRTS
James Clerk Maxwell Telescope (JCMT)
James Webb Space Telescope (JWST)
Japan Aerospace Exploration Agency (JAXA)
JUICE
Juno
K band
Keck Observatory
Keck Planet Imager and Characterizer (KPIC)
kilonova (KN)
Kuiper Airborne Observatory (KAO)
Large Binocular Telescope (LBT)
Large Millimeter Telescope (LMT)
line blanketing
Llano de Chajnantor Observatory
Lucy
luminous infrared galaxy (LIRG)
luminous red nova (LRN)
LUVOIR
Lyman break (LB)
magnitude
Mars Express
Mars Observer (MO)
maser
Max Planck Institute for Radio Astronomy (MPIR)
microwave
mid infrared (MIR)
Midcourse Space Experiment (MSX)
Mimir
MMT
MMX
Mount Wilson Observatory (MWO)
Munich Near-Infrared Cluster Survey (MUNICS)
near infrared (NIR)
NEO Surveyor
New Technology Telescope (NTT)
NEWS
NIRPS
nitrogen (N)
NOIRLab
observational astronomy
OH/IR source
OIR
optical interferometer
optics
Origins Space Telescope (OST)
PAH emissions
Palomar Observatory
panchromatic
passband
Pfund series
phase plate
photochemistry
photometric system
photomultiplier tube (PMT)
Pioneer Venus Orbiter (PVO)
polycyclic aromatic hydrocarbon (PAH)
protoplanetary disk (PPD)
Q band
radial velocity method
radio
radio astronomy
Radio Galaxy Zoo (RGZ)
radio source (RS)
radiometer
Rapid Eye Mount Telescope (REM)
rare designator prefixes
Rosalind Franklin
Rosetta
S-Star Cluster
Shane Telescope
Sloan Digital Sky Survey (SDSS)
SMART-1
SOAR Telescope (SOAR)
SOFIA
source
speckles
spectral energy distribution (SED)
SPHERE
SPICA
SPIRITS
SPIRou
Spitzer Extragalactic Representative Volume Survey (SERVS)
Spitzer Space Telescope (SST)
star formation (SF)
star formation rate (SFR)
starburst galaxy
submillimeter astronomy
T Tauri
thermal dust emission
THESEUS
Thirty Meter Telescope (TMT)
TIM
tip of the red-giant branch (TRGB)
transient (AT)
TripleSpec (TSpec)
Two Micron Sky Survey (IRC)
UBV photometric system
ugriz photometric system
UKIDSS
ultraluminous infrared galaxy (ULIRG)
United Kingdom Infrared Telescope (UKIRT)
University of Tokyo Atacama Observatory (TAO)
Uranus Orbiter and Probe
UVJ diagram
UVOIR
vegetation red edge (VRE)
Venus Express
visible light
VISTA
Voyager
water (H2O)
water lines
wavelength (λ)
WFC3
Wide Field Infrared Explorer (WIRE)
Wide-field Infrared Survey Explorer (WISE)
William Herschel Telescope (WHT)
WISE 0855-0714 (W0855)
WIYN 3.5m Telescope
X-ray luminous galaxy cluster

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