An Etymological Dictionary of Astronomy and Astrophysics
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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.

Observing a large area of sky (or the whole sky) in infrared wavelengths.

→ infrared; → survey.

A telescope capable of observing → infrared radiation from astronomical objects.

→ infrared; → telescope.

A range of infrared wavelengths to which the Earth's atmosphere is relatively transparent, and at which observations can be made from the ground. Infrared windows are found near wavelengths of 1.25, 1.65, 2.2, 3.6, 5.0, 10, 20, and 30 microns, and beyond 300 microns.

→ infrared; → window.

That which enters into a → compound or → mixture.

M.E., from L. ingredient- (nominative ingrediens) "that which enters into," p.p. of ingredi "to go in, enter," from → in- + gradi "to go, to walk," → egress.

Darâné, literally "brought into," from dar-, → in-, + ân present stem of ânidan "to bring, to lead," → relate, + nuance suffix -é.

Same as → immersion.

From → in- + gress, → egress.

The central part of the → Earth's core, composed of solidified → iron and → nickel, and extending from a depth of about 5100 km to the center of the Earth, at 6360 km. Its radius is about 1/3 that of the whole core and is effectively decoupled from the → mantle due to the molten nature of the surrounding → outer core. The radius of the inner core is defined by a small increase in → compressional wave velocity at a radius of about 1200 km. Its density is about 12 g/cm³. The → temperature of the inner core has been estimated at 5000-7000 °C.

→ inner; → core.

A → Lindblad resonance expressed by: Ω_p = Ω - κ/m.

→ inner; → Lindblad resonance.