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

Asserting the contrary or opposite; contradicting; inconsistent; logically opposite (Dictionary.com).

Adjective from → contradiction.

1) Opposite in nature or character; diametrically or mutually opposed.
2) Opposite in direction or position (Dictionary.com).

From Anglo-French contrarie, O.Fr. contrarie, and directly from L. contrarius "opposite, opposed; contrary, reverse," from contra "against"

Pârun, → opposite.

In an → image, the degree of distinction between areas with different → brightness levels; in other words, the → ratio of the brightness between light and → dark areas.

From Fr. contraster, from It. contrastare "stand out against," from V.L. *contrastare "to withstand," from L. → contra- "against" + stare "to stand," (cf. Pers. istâdan "to stand," O.Pers./Av. sta- "to stand, stand still; set," Skt. sthâ- "to stand," Gk. histemi "put, place, weigh," PIE base *sta- "to stand").

Pâdsâni, from pâd- "agianst," → contra- + sân "manner, semblance," variant sun, Mid.Pers. sân "manner, kind," Sogdian šôné "career" + -i noun suffix.

A tensor whose components are distinguished by → superscript indices.

→ contra-; + variant; → variance; → tensor.

1) To give or supply (help, money, etc.) for a common purpose.
2) To provide (ideas, suggestions, work, etc.) for a common goal, such as an article, a book.

From L. contributus, p.p. of contribuere "to bring together, unite, collect," from → com- + tribuere "to pay, assign, allot," from tribus "tribe."

Hambâžidan, from ham- "together," → com-, + bâž "tribute, toll, impost," → distribute.

1) The act of contributing.
2) Something contributed.

Verbal noun of → contribute.

In general, mass motions within a → fluid resulting in transport and mixing of the properties of that fluid when the temperature gradient exceeds some critical value. Convection, along with → conduction and → radiation, is a principal means of → energy transfer. → Schwarzschild's criterion.

From L. convectionem "the act of carrying," from p.p. stem of convehere "to carry together," from → com- "together" + vehere "to carry," cf. Skt. vah- "to carry, lead," vahitra "vehicle," Av. vazaiti "to lead," Mid.Pers. waz-, wazidan "to carry away," Gk. oxos "chariot;" PIE base *wegh- "to go, carry, drive"

Hambaz, from ham- "together" + baz "to carry, move," → evection.
Hambord, from ham- "together," → com- + bord, from bordan "to carry," Mid.Pers. burdan, O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive)," Skt. bharati "he carries," Gk. pherein, L. fero "to carry," PIE base *bher- "to carry."

Same as → convective zone.

Of or relating to → convection.

A body of → fluid which transports energy through the → convection process.

→ convective; → cell.

Meteorology: A cloud that owes its vertical development, and possibly its origin, to convection.

→ convective; → cloud.

The central region of a → massive star where → convection prevails due to steep gradient of temperature relative to pressure.

→ convective; → core.

1) A → convective zone situated beneath the surface of solar type stars.
2) Stellar models show that → massive stars also possess an outer convective envelope encompassing several percent of the stellar radius. Fast rotation amplifies the size of the convective envelope in → OB stars and developes anisotropic convective envelops (Maeder et al. 2008, A&A 479, L37).

→ convective; → envelope

In a → massive star, penetration of the upper layers of the → convective core into the → radiative zone due to → turbulence effects. The enlargement of the convective core results in more luminous stars in theoretical models.

→ convective; → overshooting.

A common feature of the atmosphere that ranges from small-scale → vortices such as → dust devils, to large-scale systems such as → cyclones.

→ convective; → vortex.

A zone inside a star in which → convection takes place; the central → core in → massive stars and the zone underneath → photosphere in low mass stars like the Sun. Recent works predict the presence of a thin convection zone in sufficiently massive main sequence stars which originates from the iron opacity and partial helium ionization. See also → iron convection zone.

→ convective; → zone.

1) General: To tend to meet in a point; incline toward each other.
2) Math: (of an infinite series) to have a finite sum. (of an improper integral) to have a finite value.

From L.L. convergere "to incline together" from → com- "together" + vergere "to bend."

Hamgerâyidan, from ham- "together," → com- + gerâyidan "to incline toward, verge on; to intend," Mid.Pers. grayidan "to lean, incline; to intend, desire," → diverge.

1) General: Act or state of converging.
2) Math: The property of a → sequence or → series which ensures that it will approach a definite → finite limit. See also: → divergence.

From converg-, from → convergent + -ence, equivalent to → -ance.

Hamgerâyi, verbal noun from hamgerâyidan, → converge.

Coming together, as a light beam after passing through a convex lens which brings the beam into the focus.

Verbal ddj. from → converge.

A concave mirror that reflects a parallel beam into a convergent beam.

From → converge + → -ing; → mirror.