An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



Number of Results: 20 Search : even
compound event
  رویداد ِ همنات   
ruydâd-e hamnât

Fr.: événement composé   

In statistics, an event whose probability of occurrence depends upon the probability of occurrence of two or more independent events.

compound; → event.

cosmic-ray event
  رویداد ِ پرتوهای ِ کیهانی   
ruydâd-e partowhâ-ye keyhâni

Fr.: événement des rayons cosmiques, un cosmique   

Spurious signals in CCD frames caused by ionizing radiation which appear as a set of pixels with intense values sparsely scattered over the CCD frame. High energy particles generate muons, which deposit around 80 electrons per micron in silicon. With a collection depth of 10-20 microns, a cosmic-ray event is seen on a CCD frame as having a signal of up to a few thousand electrons, usually concentrated in one or two pixels. Although attributed to cosmic-ray hits, they may also be due to background terrestrial radiation.

cosmic rays; → event.

Cretaceous-Paleogene extinction event
  رویداد ِ خاموشی ِ گچاسا-پارینزاد   
ruydâd-e xâmuši-ye Gacâsâ-Pârinzâd

Fr.: extinction Crétacé-Tertiaire   

The → mass extinction event that destroyed the dinosaurs and a majority of other species on Earth approximately 65 million years ago. This event is believed to have been the impact of a 10 km-size → asteroid or → comet nucleus and its aftereffects, including a severe → impact winter. The collision would have released the energy equivalent to 100 million megatonnes (teratonnes) of → TNT, i.e. more than 109 times the energy of the atomic bomb dropped on Hiroshima on August 6, 1945. Same as the → Cretaceous-Tertiary event.

Cretaceous; → Paleogene; → extinction; → event.

Cretaceous-Tertiary event
  رویداد ِ K-T   
ruydâd-e K-T (#)

Fr.: événement K-T   

See → Cretaceous-Paleogene extinction event.

K, representing the "→ Cretaceous period," and T the "→ Tertiary;" → event.

even parity
  همالی ِ زوج   
hamâli-ye zowj

Fr.: parité paire   

A classical variable which does not change upon spatial inversion, such as time, energy, angular momentum and so on. → odd parity.

Even, from O.E. efen "level; equal," from P.Gmc. *ebnaz (cf. Ger. eben; Goth. ibns); → parity.

Hamâli, → parity; zowj "pair, couple; an even number," from Ar.

ivâr (#)

Fr.: soir, soirée   

The latter part of the → day and early part of the → night. Not an astronomical term proper. → evening star.

From O.E. verb æfnung "to grow toward evening," from æfnian "to become evening," from æfen "evening," from P.Gmc. *æbando- (cf. O.H.G. aband, Ger. abend).

Ivâr "evening" (Lori, Laki êvâra; Borujerdi ivâra; Kurd. ewâra); Mid.Pers. êwârak "evening," ultimately from Proto-Ir. *upa-ayara- "end of the day," from *upa- "up, on," + *ayara- "day;" cf. Av. ayar- (aiiar-) "day;" Shughni, Roshani, Bartangi prefixed (*api-) biyôr, Sariqoli biyur "yesterday;" PIE *ayer- "day, morning;" cf. Gk. eerios "at breakfast," ariston "breakfast;" Du. eer, Ger. eher "earlier;" E. ere "soon, before (in time)."

evening star
  ستاره‌ی ِ شامگاه   
setâre-ye šâmgâh (#)

Fr.: étoile du soir   

Any bright → planet, often → Venus, seen low in the western sky after → sunset. → Hesperus.

evening; → dusk; → star.

ruydâd (#)

Fr.: événement   

1) General: Something that happens or is regarded as happening; an occurrence, especially one of some importance.
2) Einstein's relativity: An occurrence in the → space-time continuum referenced by three spatial coordinates and a complementary temporal ordinate. → world line; → space-time diagram.
3) Statistics: A subset of the → sample space.

From M.Fr. event, from L. eventus "occurrence, issue," from evenire "to come out, happen, result," from → ex- "out" + venire "to come," from PIE base *gwem- "to go, come;" cf. Mod/Mid.Pers. gâm "step, pace;" O.Pers. gam- "to come; to go;" Av. gam- "to come; to go," jamaiti "goes;" Mod.Pers. âmadan "to come;" Skt. gamati "goes;" Gk. bainein "to go, walk, step;" L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come.

Ruydâd, noun from ruy dâdan "to occur, happen," originally "to appear," from ruy "face; aspect; appearance" (Mid.Pers. rôy, rôdh "face;" Av. raoδa- "growth," in plural "appearance," from raod- "to grow, sprout, shoot;" cf. Skt. róha- "rising, height") + dâdan "to give; to command" (Mid.Pers. dâdan "to give;" O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives;" cf. Skt. dadáti "he gives;" Gk. didomi "I give;" L. dare "to give, offer," facere to make;" PIE base *do- to give").

event horizon
  افق ِ رویداد   
ofoq-e ruydâd (#)

Fr.: horizon d'événement   

1) The surface surrounding a → black hole with the property that any light ray emitted inside it cannot escape to the outer space because of the strength of the → gravitational field. The radius of the event horizon is called the → Schwarzschild radius. See also → photon sphere.
2) For an observer A at the instant t0, the surface in the → space-time that divides the collection of all events into two non-empty classes: those events that have been, are being, or will be observed by A, and those that A has never observed and will never be able to observe (J. Plebanski, A. Krasinski, 2006, An Introduction to General Relativity and Cosmology, Cambridge Univ. Press).

event; → horizon.

Event Horizon Telescope (EHT)
  تلسکوپ ِ افق ِ رویداد   
Teleskop-e Ofoq-e Ruydâd

Fr.: Télescope de l'horizon des évènements   

An international collaboration using a → very-long-baseline interferometry (VLBI) array comprising millimeter- and → submillimeter- wavelength telescopes separated by distances comparable to the diameter of the Earth. At a nominal operating wavelength of ~1.3 mm, the EHT → angular resolution (λ/D) is ~25 μas (→ micro- → arcseconds), which is sufficient to resolve nearby → supermassive black hole candidates on spatial and temporal scales that correspond to their → event horizons. EHT observations toward the elliptical → galaxy M87 succeeded in obtaining the first ever image of its supermassive black hole (EHT Collaboration, 2019, ApJL 875, L1-L6). The telescopes contributing to this result were ALMA, APEX, the IRAM 30-m telescope, the James Clerk Maxwell Telescope, the Large Millimeter Telescope Alfonso Serrano, the Submillimeter Array, the Submillimeter Telescope, and the South Pole Telescope. Petabytes of raw data from the telescopes were combined by highly specialized supercomputers hosted by the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory. The construction of the EHT and the M87 black hole observation result from decades of observational, technical, and theoretical work in close collaboration by researchers from around the world. Thirteen partner institutions worked together to create the EHT, using both pre-existing infrastructure and support from a variety of agencies. Key funding was provided by the US National Science Foundation (NSF), the EU's European Research Council (ERC), and funding agencies in East Asia.

event; → horizon; → telescope.

impact event
  رویداد ِ برخورد   
ruydâd-e barxord

Fr.: impact cosmique   

A collision between two celestial objects, specially solar system bodies, with considerable consequences. Impact events involve release of large amounts of energy. Some examples are the 1908 Siberian → Tunguska event by a → comet, the → Barringer Crater, and the collision of an → asteroid with Earth 65 million years ago, which is thought to have led to the extinction of the dinosaurs and other species of the → Cretaceous-Paleogene period.

impact; → event.

independent events
  رویدادهای ِ ناوابسته   
ruydâdhâ-ye nâvâbasté (#)

Fr.: événements indépendants   

Statistics: Two events if the occurrence of one of them gives no → information about whether or not the other event will occur; these events have no influence on each other.

independent; → event.

K-T event
  رویداد ِ K-T   
ruydâd-e K-T (#)

Fr.: événement K-T   

Same as the → Cretaceous-Tertiary event.

K, representing the "→ Cretaceous period," and T the "→ Tertiary;" → event.

microlensing event
  رویداد ِ ریزلنزش   
ruydâd-e rizlenzeš

Fr.: événement de microlentille   

The effect arising whenever a source star and lens star pass each other at an angular separation involving the → Einstein radius (RE) of the lens. The time-scale for such an event is defined as tE = RE/v, where v is the magnitude of the relative transverse velocity between source and lens projected onto the lens plane.

microlensing; → event.

odd-even nucleus
  هسته‌ی ِ تاق-جفت   
haste-ye tâq-joft

Fr.: noyau impair-pair   

Nucleus which contains an odd number of protons and an even number of neutrons.

odd; → even; → nucleus.

polarity event
  رویداد ِ قطبیگی   
ruydâd-e qotbigi

Fr.: événement de polarité   

A specific event in the history of Earth's magnetic field. Usually used in reference to a specific → polarity reversal.

polarity; → event.

haft (#)

Fr.: sept   

A → cardinal number between → six and → eight.

From M.E. seoven(e), seofne, seven, O.E. seofon, cognate with M.Du. seven, Du. zeven, O.H.G. sibun, Ger. sieben, related to Pers. haft, as below, from PIE *septm "seven."

Haft, from Mid.Pers. haft, Av. hapta Skt. sapta, Gk. hepta, L. septem.

simple event
  رویداد ِ ساده   
ruydâd-e sâdé

Fr.: événement simple   

Statistics: An event consisting of a single point of the → sample space.

simple; → event.

tidal disruption event (TDE)
  رویداد ِ گسیخت ِ کشندی   
ruydâd-e gosixt-e kešandi

Fr.: événement de rupture par effet de marée   

The process in which a star is torn apart by the → tidal forces of a → supermassive black hole. About 50% of the star's mass is eventually → accreted by the → black hole, generating a flare, which, in extreme cases of very high (→ super-Eddington) mass → accretion rates, can result in a → relativistic jet. TDEs have been proposed as sources of → ultra-high-energy cosmic rays and suggested as sources of high energy astrophysical → neutrinos (W. Winter and C. Lunardini, 2021, Nature Astronomy, arXiv:2005.06097 and references therein).

tidal; → disruption; → event.

Tunguska event
  رویداد ِ تونگوسکا   
ruydâd-e Tunguska (#)

Fr.: événement de la Toungouska   

The violent impact of a comet or meteorite in the Tunguska region of Siberia on 30 June 1908. The object exploded in the atmosphere before touching the ground at an estimated height of 5-10 km. Observers reported seeing a fireball as bright as the Sun. The explosion caused a shock wave that shook buildings and caused damage, though there was no loss of human life. The first expedition to the remote area of the explosion took place in 1927. An estimated 80 million trees covering more than 2,150 square km were flattened. The energy of the explosion is estimated to have been equivalent to that of about 15 → megatons of TNT , a thousand times more powerful than the atomic bomb dropped on Hiroshima in 1945.

From the name of the central Siberian region, Russ. Podkamennaya (Lower Stony) Tunguska River, today Krasnoyarsk Krai; → event.