An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

An → adaptive optics instrument used on the → European Southern Observatory (ESO) 3.6-m telescope at La Silla. It was an upgraded version of COME-ON-PLUS, the → Very Large Telescope (VLT) adaptive optics prototype. It had 52 → actuators and performed corrections of the mirror 200 times per second. The reference → wavefront was sensed in the → visible. The observation was done in the → near-infrared (1-5 μm).

→ adaptive; → optics; → near-infrared; → system.

A family of strong infrared emission bands at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 μm which are widely observed in a large variety of objects, such as → H II regions, → reflection nebulae, → planetary nebulae, and the → diffuse interstellar medium of our galaxy and other galaxies. Solar system objects, such as carbonaceous → meteorites and → interplanetary dust particles are also known to display these features. They are suggested to be due to → polycyclic aromatic hydrocarbons.

→ aromatic; → infrared; → band.

A diffuse radiation which consists of the cumulative infrared emission from all galaxies throughout cosmic history. It is about 50 times weaker than the → cosmic microwave background radiation (CMBR). Since the CIB is produced by the dust within such galaxies, it carries a wealth of information about the processes of star formation therein.

→ cosmic; → infrared; → background.

A portion of the far infrared radiation, including wavelengths between 100 and 1,000 microns.

→ extreme; → infrared.

Infrared radiation in the wavelength range (25-40) to (200-350) microns emitted by cold molecular/dust clouds.

→ far; → infrared.

The portion of the → electromagnetic radiation in the wavelength range between about 30 and 300 → microns. See also: → infrared radiation, → near-infrared, → mid-infrared, → submillimeter radiation.

→ far; → infrared.

The invisible part of electromagnetic spectrum possessing wavelengths between those of visible light and those of radio waves, i.e. approximately between about 0.75 and 1000 μm.

From L. infra (adv., prep.) "below, underneath, beneath," inferus "lower," from PIE *ndher; cf. Av. aδara- (adj.), aδairi- (prep.) "below;" Mid.Pers. êr "below, down; low, under," adar "low," azêr "below, under" (Mod.Pers. zir "below, down"); Skt. ádhara- "lower;" O.E. under "under, among"); → red.

Forusorx, from foru "down, downward; below; beneath;" Mid.Pers. frôt "down, downward;" O.Pers. fravata "forward, downward;" cf. Skt. pravát- "a sloping path, the slope of a mountain," + sorx→ red.

A two-dimensional infrared imaging device, consisting of an array of small, individual electronic detectors, each of which records a pixel in the image.

→ infrared; → array.

An orbiting infrared telescope (60 cm mirror) which successfully operated from launch in January 1983 until the supply of coolant ran out in November 1983. It was a collaborative mission between NASA, the Netherlands, and the UK, and mapped 95% of the whole sky in the wavelength bands 12, 25, 60, and 100 microns.

→ infrared; → astronomical; → satellite.

The study of infrared properties of astronomical objects.

→ infrared; → astronomy.

An optical camera equipped with a → detector which is sensitive to → infrared radiation.

→ infrared; → camera.

Wispy, extended structures seen above and below the plane of the Galaxy in the infrared maps of the sky (60-100 microns) produced by the → Infrared Astronomical Satellite (IRAS).

→ infrared; L. cirrus "curl, tuft, plant filament like a tuft of hair."

A → dark cloud characterized by a → visual extinction A_v≥ 10² mag. IRDCs are opaque even at 8 μm, and can be seen in silhouette against the bright diffuse → mid-infrared emission in the → interstellar medium.

→ infrared; → dark; → cloud.

A thermal device for observing and measuring → infrared radiation.

→ infrared; → detector.

The portion of → electromagnetic radiation from → astrophysical objects in → infrared frequencies.

→ infrared; → emission.

Infrared → emission from a star in excess of that expected from a → blackbody with the temperature corresponding to the temperature of the star.

→ infrared; → excess.

A galaxy that emits most of its energy in the infrared region of the spectrum. Such galaxies are thought to have unusually high rates of star formation and are also described as → starburst galaxies.

→ infrared; → galaxy.

Imaging with an infrared detector.

→ infrared; → imaging.

That part of the → electromagnetic radiation lying beyond the red, between the radio and the visible regions of the → electromagnetic spectrum. The wavelengths range from about 0.8 → microns (μm) to about 1000 μm. See also: → near-infrared; → mid-infrared; → far-infrared; → submillimeter radiation.

→ infrared; → radiation.

A European Space Agency satellite which carried the most sensitive infrared telescope ever launched. It operated between November 1995 and April 1998 and made particularly important observations of the dusty regions of the Universe. ISO was equipped with four science instruments: an infrared camera (CAM), a long-wavelength spectrometer (LWS), a photo-polarimeter (PHT), and a short-wavelength spectrometer (SWS). The instruments jointly covered wavelengths from 2.5 to around 240 microns with spatial resolutions ranging from 1.5 arcseconds to 90 arcseconds. Its 60 cm diameter telescope was cooled by superfluid liquid helium to temperatures of 2-4 K. The mission was a great technical, operational and scientific success. During its routine operational phase, ISO successfully made some 30,000 individual imaging, photometric, spectroscopic, and polarimetric observations ranging from objects in our own solar system to the most distant extragalactic sources.

→ infrared; → space; → observatory.