An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < K c Kep Ker kin Knu > >>

Number of Results: 94

Fr.: Kerwan   

The largest → impact cratrer on → Ceres, which has a diameter of about 280 km. It is distinctly shallow for its size.

Named for The crater is named after the Hopi spirit of sprouting maize, Kerwan. The name was approved by the IAU on July 3, 2015.[1]


Fr.: ket   

In Dirac's notation, a vector which describes the state of a quantum system, whether it is in a space of finite or infinite dimensions. A ket vector, written as | A >, is the dual of the → bra. Like the bra, it appears as an incomplete → bracket expression.

From -ket the second syllable in → bracket.


Fr.: keV   

Kilo (thousand) → electron volt. A unit of → energy used to describe the total energy carried by a → particle or → photon.

kilo- + → electron volt.

kelid (#)

Fr.: clé   

A usually metal instrument used to operate a lock's mechanism.

M.E. key(e), kay(e), O.E. cæg "key," of unknown origin,

Kelid, variants (Tabari) kali, (Lori) kelil, (Laki) kalil "key; lock," (Kurd) kilil, kolun "latch, bolt;" Mid.Pers. kilêl "key." See also → include.

  سوراخ ِ کلید   
surâx-e kelid (#)

Fr.: trou de serrure   

1) The hole in which a key of a lock is inserted.
2) → Keyhole Nebula.
3) A small, about 600 m wide, region of space close to the Earth where the Earth's gravity would perturb the trajectory of a passing → Near-Earth Object. The object will receive a gravitational push that will bring it back for a collision in the future. Also called resonance keyhole.

key; → hole.

Keyhole Nebula
  میغ ِ سوراخ ِ کلید   
miq-e surâx-e kelid

Fr.: Nébuleuse du Trou de Serrure   

A relatively small and dark cloud of molecules and dust seen silhouetted against the much brighter → Carina Nebula. It contains bright filaments of emitting hot gas and is roughly 7 → light-years in size.

keyhole; → nebula. The name was given by the English astronomer Sir John Herschel in the 19th century, because of the appearance of the nebula in low-resolution telescopes of that epoch.

Killing vector
  بردار ِ کیلینگ   
bordâr-e Killing

Fr.: vecteur de Killing   

A → vector field on a → Riemannian manifold (or → pseudo-Riemannian manifold) that preserves the → metric. In other words, the → derivative of the metric with respect to this vector field is null.

Named after the German mathematician Wilhelm Killing (1847-1923); → vector.

kilo- (#)

Fr.: kilo-   

A prefix meaning 103.

Introduced in France in 1795, when the → metric system was officially adopted, from Gk. khilioi "thousand," of unknown origin.

kilogram (kg)
kilogram (#)

Fr.: kilogramme   

The basic unit of mass in the → International System of Units (SI) and → MKS versions of the → metric system, equal to 1,000 → grams. The kilogram was until 2019 defined as the mass of the standard (international prototype) kilogram, a platinum-iridium cylinder kept at the International Bureau of Weights and Measures (BIPM), at Sèvre, near Paris, France. Copies of this prototype are kept by the standards agencies of all the major industrial nations. A kilogram is equal to the mass of 1,000 cubic cm of water at 4°C (→ maximum density). According to the new (2019) definition, the kilogram is defined by taking the fixed numerical value of the → Planck constant (h) to be 6.62607015 × 10-34 when expressed in the unit J.s, which is equal to kg m2 s-1, where the meter and the second are defined in terms of c and Δν Cs.

kilo-; → gram.

kilogram-force (kgf)
kilogram-niru (#)

Fr.: kilogramme-force   

A metric unit of force which is equal to a mass of one kilogram multiplied by the standard acceleration due to gravity on Earth (9.80665 m sec-2). Therefore one (1) kilogram-force is equal to 1 kg × 9.80665 m sec-2 = 9.80665 → newtons.

kilogram; → force.

kilohertz (kHz)
kilohertz (#)

Fr.: kilohertz   

A unit of → frequency, equal to 103 Hz.

kilo-; → hertz.

kilometer (km)
kilometr (#)

Fr.: kilomètre   

A unit of length, equal to 1000 meters.,

kilo-; → meter.


Fr.: kilonova   

A fast-evolving → supernova-like phenomenon resulting from the → merger of compact, binary objects such as two → neutron stars or a neutron star and a → black hole. A kilonova represents an → electromagnetic counterpart to → gravitational waves. Also called → macronova. A simple model of the phenomenon was put forward by Li and Paczynski (1998, ApJL 507, L59). The kilonova phenomenon can last between days and weeks following the merger. Within the small volume of space where a merger occurs, the combination of a huge amount of energy, and a large number of neutrons, is the instigator for the → r-process. The high density favors this rapid → neutron capture by nuclei, leading to the formation of new → chemical elements with high → atomic numbers and high → atomic weights. Many elements heavier than → iron form in these environments, including many rare elements, most notably → platinum (atomic number 78) and → gold (atomic number 79). The decay of heavy atomic nuclei leads to the radioactive heating and a release of electromagnetic radiation. The heat cannot easily escape as radiation, because of the high opacity of the ejected material. The heat is radiated thermally, heating up the nearby matter, which can be then seen in the → near-infrared. It was long thought that the r-process could also occur during core-collapse supernovae, but the density of neutrons within supernovae appears to be too low. The first indication of a kilonova following a short GRB came from the extensive follow-up of GRB 130603B, which was one of the nearest and brightest short GRBs ever detected, and also the first short GRB with an optical afterglow spectrum. The first kilonova found to be associated with a gravitational waves was detected in the study of → GW170817.

The term kilonova was introduced by Metzger et al. (2010, MNRAS 406, 2650), who argued that the peak luminosities of neutron star merger transients are typically ~ few × 1041 erg s-1, or a factor of ~ 103 larger than the → Eddington luminosity for a solar mass object. They therefore dubbed these events kilonovae; from → kilo-; → nova.

kiloparsec (kpc)
kilopârsek (#)

Fr.: kiloparsec   

A unit of distance equal to 1,000 → parsec (pc)s, or 3,260 → light-years.

kilo-; → parsec.

kilowatt-hour (kWh)
kilowatt-sâ'at (#)

Fr.: kilowatt-heure   

A unit of energy equivalent to one kilowatt (1 kW) of power expended for one hour (1 h) of time. The kilowatt-hour is not a standard unit in any formal system, but it is commonly used to measure the consumption of electrical energy. To convert to → joules, use: 1 kWh = 3.6 × 106 J = 3.6 × 1013ergs.

kilo-; → watt-hour.

  جنبشی، جنبشیک   
jonbeši, jonbešk

Fr.: cinématique   

Of or relating to → kinematics. Same as kinematical.


kinematic bias
  ورک ِ جنبشی   
varak-e jonbeši

Fr.: biais cinématique   

A systematic error introduced in a sample of stellar → proper motion data by higher velocity stars that are easier to measure.

kinematic; → bias.

kinematic viscosity
  وشکسانی ِ جنبشیک   
vošksâni-ye jonbešik

Fr.: viscosité cinématique   

The ratio of the → dynamic viscosity (η) to the density (ρ) of a fluid: ν = η/ρ. The unit of kinematic viscosity in the → SI system is m2s-1. In the → cgs system, cm2s-1, equal to 10-4 m2s-1, is called the → stokes (st).

kinematic; → viscosity.

  جنبشی، جنبشیک   
jonbeši, jonbešik

Fr.: cinématique   

Of or relating to → kinematics. → kinematic.

kinematic; → -al.

kinematically decoupled core (KDC)
  مغزه‌ی ِ جنبشیکانه واجفسریده   
maqze-ye jonbešikâné vâjafsaridé

Fr.: cœur cinématiquement découplé   

A central, tightly bound stellar subsystem observed in some elliptical galaxies which rotates in the opposite direction with respect to the main body of the → elliptical galaxy. Elliptical galaxies are thought to be the result of the → merger of two or more sizable galaxies. A plausible scenario for how counter-rotating cores could form in such a merger is as follows. If at least one of the galaxies has a core region that is fairly tightly bound by the galaxy's gravity, and the direction in which the two galaxies orbit each other before merging is opposite to the direction of rotation of stars in that tightly bound core, it is likely that, after the merger, the tightly bound core will end up as the core of the new, larger galaxy, while retaining its original sense of rotation. The surrounding stars, on the other hand, will rotate in a different way dictated by the orbital motion of the galaxies around each other, before the merger. While this is a plausible scenario, it can only explain some of the counter-rotating cores. Recently A. Tsatsi et al. (2015, ApJ 802, L3) have shown that although the two → progenitor galaxies are initially following a → prograde orbit, strong reactive forces during the merger can cause a short-lived change of their orbital spin; the two progenitors follow a → retrograde orbit right before their final coalescence. This results in a central kinematic decoupling and the formation of a large-scale (~2 kpc radius) counter-rotating core at the center of the final elliptical-like merger remnant, while its outer parts keep the rotation direction of the initial orbital spin.

kinematical; → decouple; → core.

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