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

The act or an instance of discovering. Something discovered.

Verbal noun of → discover.

A → radio interferometer array consisting of 27 25-meter diameter antennas located on the Plains of San Agustin in West-Central New Mexico. EVLA will operate at any frequency between 1.0 and 50 GHz and will have a continuum sensitivity improvement over the → VLA by factors of 5 to 20.The EVLA project is expected to be completed in 2012. See also the EVLA homepage.

→ expand; → very; → large; → array.

Any theory that attempts to describe all the forces of nature including gravity in a single mathematical formalism; e.g. → grand unified theory. → string theory.

→ theory; every; M.E. every, everich; O.E. æfre ælc "ever each;" → thing.

Negaré, → theory; hamé, → all; ciz, → thing.

In a high degree. → Very Large Telescope (VLT); → very massive star; → very high frequencies (VHF).

M.E.; O.Fr verai "true;" L. verax (genitive veracis) "truthful," from verus "true."

Besyâr, from bas "many, much" (Mid.Pers. vas "many, much;" O.Pers. vasiy "at will, greatly, utterly;" Av. varəmi "I wish," vasô, vasə "at one's pleasure or will," from vas- "to will, desire, wish").

Radio frequencies in the range 30 to 300 mega Hz.

→ very; → high; → frequency.

A radio interferometer consisting of 27 antennas, each 25 m in diameter, in a Y-shaped configuration. It is located about 100 km west of Socorro, New Mexico, and is operated by the United States National Radio Astronomy Observatory. The VLA has the resolution of a single antenna 36 km wide and the sensitivity of a dish 130 m across.

→ very; → large; → array.

A network of ten 25-m radio telescopes for → very-long-baseline interferometry (VLBI), operated by the U.S. National Radio Astronomy Observatory. Eight of the VLBA telescopes are distributed across the continental United States, while the other two are in Hawaii and the Virgin Islands, giving a maximum baseline of about 8,000 km and a resolution better than a milliarcsecond at its shortest wavelength.

→ very; → large; → baseline; → array.

An observing facility consisting of four 8.2 m telescopes, with the combined collecting area of a 16 m mirror, owned and operated by the European Southern Observatory at an altitude of 2635 m at the Paranal Observatory in Chile. The four reflecting unit telescopes are called Antu "Sun" in the language of Chile's indigenous Mapuche people, Kueyen "Moon," Melipal "Southern Cross," and Yepun "Venus." Each unit is equipped with several sophisticated instruments. The light of the individual telescopes can be combined using interferometric techniques to achieve superior resolution. → VLT Interferometer (VLTI). The wavelength range covered by the VLT is extremely wide, ranging from deep ultraviolet to mid-infrared.

→ very; → large; → telescope.

In evolutionary models of → post-asymptotic giant branch stars, the occurrence of the helium shell burning when the star has reached the → white dwarf cooling track. This leads to the possibility of a violent → helium shell flash and expansion on a time-scale of ≤ 10 years. The rapid expansion and prompt change in surface composition observed in → Sakurai's Object are thought to be due to such a very late thermal pulse.

→ very; → late; → thermal; → pulse.

A star with a typical mass of one-hundredth of the mass of the Sun (→ solar mass) and a luminosity of about one-millionth that of the Sun (→ solar luminosity). Same as → brown dwarf.

→ very; → low; → mass; → star.

A star of mass around 100 → solar masses. See also: → supermassive star, → massive star, → canonical upper limit.

→ very; → massive; → star.

A special type of carbonaceous → interstellar dust grains with a size ranging from 10 to 150 Å and consisting of tens to hundreds of atoms. In contrast to → big grains, VSGs are not in → thermal equilibrium. They can be heated to very high temperatures (~ 1000 K) by the absorption of a single photon. It is thought that VSGs are clusters of → PAH.

→ very; → small; → grain.

A technique in radio interferometry in which the individual telescopes are not directly connected together, but instead make their observations separately with very accurate timings. The data are later sent to a central correlator to be combined. With this technique the individual telescopes can be arbitrarily far apart, and so the technique provides the highest resolution images in astronomy, typically down to a few milliarcseconds.

→ very; → large; → baseline; → interferometry.