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

Audible disturbance or wave caused by the compression of air ahead of a projectile in flight.

→ ballistic; → wave.

The science of the motion and behavior of → projectiles. The study of the functioning of firearms.

From L. ballista "ancient military machine for hurling stones," from Gk. ballistes, from ballein "to throw," from PIE *g^welH₁- "to throw;" cf. Pers. garzin "arrow;" Av. niγr- "to throw down;" Khotanese (+ *abi-, *ui-) bīr- "to throw, sow;" Proto-Iranian *garH- "to throw."

Partâbik, from partâb "a throw, an arrow that flies far," partâbidan "to throw," + -ik, → -ics; partâbšenâsi, from partâb + -šenâsi, → -logy.

A defect in an optical system in which magnification decreases with distance from the optical axis, whereby the image of a square appears barrel-shaped. Opposite of → pincushion distortion.

Barrel, M.E. barel, from O.Fr. baril; → distortion.

Cowlegi, → distortion; celiki, relating to celik "barrel".

A statistics based on a → biased sample.

→ biased; → statistics.

A probability distribution for independent events for which there are only two possible outcomes i.e., success and failure. The probability of x successes in n trials is: P(x) = [n!/x!(n - x)!] p^x.q^{n - x}, where p is the probability of success and q = 1 - p the probability of failure on each trial. These probabilities are given in terms of the → binomial theorem expansion of (p + q)ⁿ.

→ binomial; → distribution.

An expert or specialist in biology.

Biologist, from → biology + → -ist.

A specialist in → biophysics.

→ bio-; → physicist.

The condition in which a physical system is capable of assuming either of two stable states.

→ bi-; → stable.

An abrupt discontinuity in the → stellar wind properties of → hot stars near → effective temperatures about 21,000 K and 10,000 K, corresponding to O9.5-B3 supergiants (Castor et al. 1975, ApJ 195, 157; Lamers et al., 1995, ApJ 455, 269). At these temperatures the → terminal velocity of the wind drops steeply by about a factor two and the → mass loss rate increases steeply by about a factor three to five, when going from high to low temperatures. Bistability jump is related to the degree of ionization in the wind. With a little drop in the temperature, the dominant driving element (Fe) will recombine to lower ionization stages which produces a lower terminal velocity and a relatively high density in the wind. → wind momentum. Additional bistability jumps may occur at higher temperatures where CNO may provide the dominant line driving, especially for low metallicity stars (Vink et al. 2001, A&A 369, 574). However, a recent study using a larger sample finds that there is a gradual decline in the wind terminal velocities of early B supergiants and not a "jump" (Crowther et al. 2006, A&A 446, 279).

→ bistability; → jump.

The mechanism that accounts for the → bistability jump.

→ bistability; → mechanism.

A small cyst on the skin, containing watery liquid, as from a burn or other injury.

M.E. blister, blester, from O.Fr. blestre, of Germanic origin.

Tâval "blister" (variants Torbet-Heydariye-yi toval, Guqari tavol), from suffixed (-al) tâv- tav, taf- "to heat, burn, shine," variant of tâb-, tâbidan "to shine," → luminous.

A model according to which an → H II region is a hot mass of ionized gas located on the surface of a → molecular cloud, like a blister on the body skin.

→ blister; → model.

For a → population of independent → bosons, a function that specifies the number of particles in each of the allowed → energy states.

→ boson; → Einstein; → distribution.

Same as → Bose-Einstein distribution.

→ boson; → Einstein; → statistics.

A statistical distribution of the brightness of an astronomical extended object.

→ brightness; → distribution.

Vâbâžeš, → distribution; deraxšandegi, → brightness.

The eighth of → Jupiter's known moons and the second brightest and the outermost of the four → Galilean satellites. With a diameter of 4800 km (0.38 Earths), Castillo is roughly the same size as Mercury. It orbits Jupiter in 16.689 days at a distance of 1,883,000 km from the planet, beyond Jupiter's main → radiation belts. It is the third largest moon in the entire solar system. Its mass is 10.76 × 10²² kg (about 1.5 Earth Moons) and its mean → surface temperature is -155 °C. The most prominent feature of Callisto is its craters, as it has the most craters of any object in the solar system. Due to its orbit being further away from Jupiter, it is not under the same → tidal heating influences as → Io, → Europa, or → Ganymede. Callisto's thin → atmosphere is composed of → carbon dioxide and likely some → molecular oxygen. Callisto is thought to have formed as a result of slow → accretion from the → protoplanetary disk of gas and dust that surrounded Jupiter after its formation.

Callisto, an attendant of Artemis in Greek mythology. Because of her love affair with Zeus, she was transformed into a bear by Artemis. According to another legend she was changed into a bear by the jealous Hera. Zeus transferred her to the heavens as the → constellation  → Ursa Major (great bear).

1a ) A distinguishing feature or quality.
1b) The integer part of a → common logarithm. For example, log₁₀ (23) = 1.362, where the characteristic is 1 and the → mantissa is 0.362.
2) Pertaining to, constituting, or indicating the character or peculiar quality of a person or thing; typical; distinctive.

→ character; → -istic.

Of a pulsar, a normalized period of rotation assumed to be a good approximation to pulsar's true age.

→ characteristic; → age.

Graph representing an optical film's response to the amount of light falling on it.

→ characteristic; → curve.

Physics: An analytical relationship between a set of physical variables that determines the state of a physical system.
Math.: The equation which is solved to find a matrix's eigenvalues, also called the characteristic polynomial.

→ characteristic; → equation.