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

The mathematical problem of studying the behavior (e.g., velocities, positions) of any number of objects moving under their mutual gravitational attraction for any time in the past or future. Same as the → many-body problem.

→ body; → problem.

The conductivity in a semiconductor caused by a flow of electrons, whereas p-type conductivity is caused by a flow of holes.

n standing for → negative; → type; → conductivity.

The largest and the most luminous → H II region in the → Small Magellanic Cloud, which contains the prominent OB star cluster → NGC 346. N66 has a diameter of about 7 arcmin on the sky corresponding to about 120 pc for a distance of about 60 kpc. Compared with the → Orion Nebula, N66 has an Hα luminosity almost 60 times higher.

Serial number in the Henize (1956) catalog, more precisely designated as LHA 115-N66.

→ D line.

Na, → sodium; → D line.

Same as → Iota Orionis.

From Ar. Nayyir al-Saif (نیر‌السیف) "the Bright One in the Sword," from nayyir (نیر) "bright" + al-saif (السیف) "sword."

The mathematical symbol for the → del operator.

From Gk. nabla an ancient stringed instrument, triangular in shape and held like a harp, thus of the shape of ∇.

An → adaptive optics instrument at the → European Southern Observatory (ESO) → Very Large Telescope (VLT) in service since 2001. It provides adaptive optics assisted imaging, imaging polarimetry, and → coronagraphy (only L) in the 1-5 μm range. It consists of two components: NAOS (Nasmyth Adaptive Optics System) and CONICA (COudé Near Infrared CAmera). The adaptive optics system, NAOS, is equipped with both → visible and → infrared→ wavefront sensors. It contains five → dichroic filters which split the light from the telescope between CONICA and one of the NAOS wavefront sensors. CONICA is the → infrared camera and → spectrometer attached to NAOS and equipped with an Aladdin 1024 × 1024 pixel InSb array detector. It possesses several wheels carrying masks/slits (including focal plane coronagraphic masks), filters, polarizing elements, → grisms and several cameras allowing → diffraction-limited sampling across the full wavelength range.

NaCo, from NAOS (→ Nasmyth, → adaptive; → optics; → system) + CONICA (→ coude; → near-infrared; → camera).

The point on the celestial sphere blocked from view by Earth and diametrically opposite to the → zenith (سرسو).

From M.L. nadir, from Ar. nazir "opposite to," contraction of nazir as-samt (نظیر‌السمت), literally "opposite of the zenith," from nazir "opposite" + samt "zenith."

Pâsu, literally "direction of the foot," from pâ "foot, step" (from Mid.Pers. pâd, pây; Khotanese fad; Av. pad- "foot;" cf. Skt. pat; Gk. pos, genitive podos; L. pes, genitive pedis; P.Gmc. *fot; E. foot; Ger. Fuss; Fr. pied; PIE *pod-/*ped-) + su "direction, side" (from Mid.Pers. sôk "direction, side").

1) A small metal spike with a broadened flat head, driven into wood to join things together or to serve as a hook.
2) A horny covering on the upper surface of the tip of the finger and toe in humans and other primates (OxfordDictionaries.com).

M.E. nail(l), nayl(l), O.E. negel "metal pin," nægl "fingernail;" cf. O.Norse nagl "fingernail," nagli "metal nail;" O.H.G. nagel, M.Du. naghel, Du. nagel, Ger. Nagel "fingernail, small metal spike;" from PIE root *h3nog^h- "nail" (source also of Gk. onyx "claw, fingernail;" L. unguis (Fr. ongle, from diminutive L. ungula) "nail, claw;" Pers. nâxon, as below; Lithuanian naga "hoof," nagutis "fingernail."

1) Mix, from Mid.Pers. mêx "peg, nail;" O.Pers. mayūxa- "doorknob;" cf. Skt. mayūkha- "peg for stretching the woof").
2) Nâxon "nail;" Mid.Pers. nâxun "nail;" cf. Skt. nakha-; Russ. noga; E. nail, as above.

Not accompanied or supplemented by anything else. → naked eye, → naked singularity, → naked-eye star.

O.E. nacod "nude;" cf. M.Du. naket, Du. naakt, Ger. nackt, cognate with Pers. berehné, as below, , from PIE base *neg^w-no- "naked."

Berehné, from Mid.Pers. brahnag (with secondary -r-) "naked;" Av. maγna- "naked;" cf. Skt. nagná- "naked;" Gk. gumnos "naked;" L. nudus "naked;" Arm. merk "naked;" Lith. nuogas "naked;"

The qualifier of an eye which is not assisted by any optical device, except for eyeglasses. Same as → unaided eye.

→ naked; → eye.

A singularity that is not surrounded by an event horizon. It will therefore be visible and communicable to the outside world.

→ naked; → singularity.

A star visible without a telescope. In principle, stars down to about sixth magnitude are visible to the naked eye under ideal conditions, but this depends on the individual, the location, and the conditions of the observation.

→ naked; → eye; → star.

A word or term by which somebody or something is commonly and distinctively known.

M.E., from O.E. nama; cf. O.H.G. namo, Ger. Name, Du. naam, Goth. namo "name;" cognate with Pers. nâm, as below.

Nâm "name;" Mid.Pers. nâm; O.Pers./Av. nâman-; cf. Skt. nama-; Gk. onoma, onuma; L. nomen; PIE *nomen-.

A prefix denoting 10^-9.

Combining form of Gk nanos "dwarf."

The most stable carbon compound with an average particle size of about 5 → nanometers (50 Å). Nanodiamonds are synthesized by detonation of → T.N.T. and then gathering the soot that remains from the explosion.

→ nano-; → diamond.

Dust grains at → nanoscale sizes found in various astrophysical environments, such as → interstellar medium and → interplanetary space of our Solar System.

→ nano-; → dust.

A unit of length equal to 10^-9 m, or 10 Å.

→ nano-; → meter.

A solid particle of → nanoscale size; e.g. a → nanodust grain.

→ nano-; → particle.

The size range from approximately 1 → nanometer (nm) to 100 nm.

→ nano-; → scale.