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

Having an intense, powerful, or vivid effect.
→ strong anthropic principle, → strong arm spiral galaxy, → strong encounter, → strong force, → strong gravitational lensing, → strong interaction, → strong lensing.

O.E. strang "physically powerful, powerful in effect, forceful;" cf. O.N. strangr "strong," Du. streng "strict, rigorous," O.H.G. strang "strong, bold, hard," Ger. streng "strict, rigorous."

Sotorg "large, strong," Mid.Pers. sturg "fierce; gross, coarse," Av. stūra- "strong, large, rough," stāuuišta- "strongest, biggest," cf. Skt. sthūrá- "strong, big, massy, thick," Gk. stylos "column, pillar," M.L.G. stūr "big, strong, coarse."
Zurmand, from zur, → strength, + -mand possession suffix.
Nirumand, from niru, → force + -mand possession suffix.

A version of the → anthropic principle that claims that the → Universe must be suitable for the formation of → intelligent life at some point. Compared with the → weak anthropic principle, this version is very controversial. Its implications are highly speculative from a scientific viewpoint.

→ strong; → anthropic; → principle.

A galaxy with prominent stellar → spiral arms and little star formation between stellar arms, such as M51.

→ strong; → arm; → spiral; → galaxy.

In a star cluster, a → close encounter that strongly changes a star's velocity.

→ strong; → encounter.

The force responsible for holding quarks and gluons together to form protons, neutrons and other particles. It is the strongest of the four fundamental forces. Same as → strong interaction.

→ strong; → force.

A → gravitational lensing phenomenon in which the image distortion is strong enough to be readily recognized, such as in the case of the → Einstein cross or when giant luminous arcs show up in → galaxy clusters (e.g. Abell 2218). Opposite to → weak gravitational lensing.

→ strong; → gravitational; → lensing.

The interaction between quarks that is transmitted by gluons. The characteristic range of the strong interaction is 10^-13 cm, and the time scale over which it operates is on the order of 10^-23 second. Also called → strong force.

→ strong; → interaction.

A situation where the mass concentration in the central regions of → galaxy clusters exceeds the → critical density required for lensing, resulting in multiple images of background objects.

→ strong; → lensing.

A metallic chemical element; symbol Sr. Atomic number 38; atomic weight 87.62; melting point 769°C; boiling point 1,384°C; specific gravity 2.6 at 20°C. Strontium is a soft, silver-yellow metal with three allotropic crystalline forms. It is found in nature only in the combined state, as in strontianite. It is used in fireworks, flares, and tracer bullets. The radioactive isotope Strontium-87, the daughter of Rubidium-87, has a half-life of 48.8 x 10⁹ years.

The name derives from Strontian "a town in Scotland." The mineral strontianite is found in mines in Strontian. The element was discovered by the Scottish chemist and physician Thomas Charles Hope in 1792 observing the brilliant red flame color of strontium. It was first isolated by the English chemist Humphry Davy in 1808.

The arrangement of parts in an object or organism.

M.E., from L. structura "a fitting together, adjustment, building," from structus, p.p. of struere "to pile, build, assemble," related to strues "heap," from PIE *stere- "to spread, extend, stretch out;" cf. Pers. gostar-, gostardan "to spread;" Av. star- "to spread," starati "spreads;" Skt. star- "to spread out, extend, strew," strnati "spreads;" Gk. stornumi "I spread out," strotos "spread, laid out;" Ger. Strahlung "radiation," from strahlen "to radiate," from Strahl "ray;" from M.H.G. strāle; from O.H.G. strāla "arrow, stripe."

Sâxtâr, from sâxt "made; make, construction, structure; style," past stem of sâxtan, sâzidan "to build, make, fashion; to adapt, adjust, be fit" (Mid.Pers. sâxtan, sâz-, Manichean Parthian s'c'dn "to prepare, to form;" Av. sak- "to understand, to mark," sâcaya- (causative) "to teach") + -âr verbal noun suffix.

The study of the processes that gave rise to the apparition of matter concentrations, such as → superclusters of galaxies, → galaxy clusters, and galaxies, in a homogeneous → expanding Universe. Cosmic structures are believed to result from → density fluctuations that existed in the → early Universe before radiation and matter decoupled (→ decoupling era or → recombination era). Initial → quantum fluctuations in the → inflaton field were expanded by → inflation. Inflation amplified them up to scales that correspond to those of galaxy clusters and beyond. Generally, a model of structure formation includes three main ingredients: 1) background cosmology, 2) model for fluctuation generation, and 3) types of → dark matter.
See also:
→ bottom-up structure formation, → hierarchical structure formation, → Silk damping, → top-down structure formation.

→ structure; → formation.

1a) Application of the mind to the acquisition of knowledge, as by reading, investigation, or reflection.
1b) The cultivation of a particular branch of learning, science, or art.
1c) Something studied or to be studied.
1d) Research or a detailed examination and analysis of a subject, phenomenon, etc. A written account of such research, examination, or analysis.
2a) To apply oneself to the acquisition of knowledge, as by reading, investigation, or practice.
2b) To think deeply, reflect, or consider.
2c) To take a course of study, as at a college (Dictionary.com).

M.E. studie, from O.Fr. estudie "care, skill, thought; study, school," from L. studium "study, application;" originally "eagerness," from studere "to press forward, be eager for, pursue," from PIE *(s)teu- "to push, stick, beat;" cf. Gk. typtein "to strike," typos "a blow, mold;" Skt. tup- "harm," tundate "pushes, stabs;" Gothic stautan "push."

Parhâné, from Proto-Ir. *pari-huan- "to read thoroughly, to read through," from *pari- "through, throughout; thoroughly" (O.Pers. pariy "around, about;" Av. pairi "around, over") + *huanH- "to call;" cf. Pers. xândan, x^vandan "to read, to sing" (Av. x^van- "to sound;" Skt. svana- "sound," svan- "to sound," svanati "it sounds;" O.E. swinn "music, song"); cf. Kurd. xwendin "to study, read;" Lori hané "to read;" Karingâni hoyniyan, Baluci vonag, Awromâni wânây "to read;" Khotanese hâvn- "to speak."

The fifth confirmed → satellite of → Pluto discovered in 2012 using a set of the → Hubble Space Telescope. Also called Pluto V (P5). It orbits Pluto between → Charon and → Nix at a distance of about 42,000 km. Styx is estimated to have a diameter of between 10 and 30 km, and an → orbital period of 20.2 days.

Named for the Greek mythological river that separates the world of the living from the realm of the dead.

A prefix occurring originally in loanwords from L. but freely attached to elements of any origin and used with the meaning "under, below, beneath."

From L. preposition sub "under" (also "next to, up to, toward"), from PIE base *upo- "from below," hence "turning upward, upward, up, over, beyond;" cf. O.Pers. upā (prep.) "under, with;" Av. upā, upa (prep.; prevb) "toward, with, on, in" (upā.gam- "to arrive at," upāpa- "living in the water," upa.naxturušu "bordering on the night"); Mod.Pers. bâ "with," from abâ; Skt. úpa (adv., prevb., prep.) "toward, with, under, on;" Gk. hypo "under;" Goth. iup, O.N., O.E. upp "up, upward."

Zir- "below, down;" Mid.Pers. azêr "below, under," êr "below, down; low, under," adar "low;" Av. aδara- (adj.), aδairi- (prep.) "below;" cf. Skt. ádhara- "lower;" L. infra (adv., prep.) "below, underneath, beneath," inferus "lower;" O.E. under "under, among"); PIE base *ndher.

A measure of angle smaller than 1 arcsecond, usually until 0.1 arcsecond.

→ sub-; → arc second.

Imaging in excellent seeing conditions using an adequate detector to obtain stellar images whose profile lies in the sub-arcsecond range.

→ sub-arcsecond; → imaging.

A part of a larger image.

→ sub-; → image.

Of, relating to, or being smaller than the atom; of or relating to the inside of the atom.

→ sub-; → atomic.

Any particle that is small compared to the size of the atom, e.g. an electron, proton, neutron, neutrino, quark, meson, all of which are either bosons or fermions.

→ subatomic; → particle.

A smaller group among several into which a main class is divided, e.g. subclasses a and b among supergiants. → subtype.

→ sub-; → class.