An Etymological Dictionary of Astronomy and Astrophysics

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

Etymology (EN): 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.”

Etymology (PE): 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.

See also: → sub-; → arc second.

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

See also: → sub-arcsecond; → imaging.

A part of a larger image.

See also: → sub-; → image.

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

See also: → 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.

See also: → subatomic; → particle.

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

See also: → sub-; → class.

Of or pertaining to a state, value, or quantity that is less than critical, especially the condition of a → subcritical reactor.

See also: → sub-; → critical.

An amount of → fissile material that by its mass or geometry is incapable of sustaining a → fission → chain reaction.

See also: → subcritical; → mass.

A → nuclear reactor in which the
rate of production of → fission neutrons is lower than the rate of production in the previous generation, and therefore the number of fissions decreases over time.

See also: → subcritical; → reactor.

Geology: The process by which one tectonic plate slides down and below another tectonic plate as the two converge. The subduction zone is the zone of convergence of two tectonic plates, one of which usually overrides the other.

Etymology (EN): From L. subductionem (nominative subductio), from subductus, p.p. of subducere “to draw away, withdraw, remove,” from → sub- + ducere “to lead.”

Etymology (PE): Zir-hâzeš, verbal noun of zir-hâzidan, from zir-→ sub- + hâzidan, hâxtan, from Mid.Pers. “to lead, guide, persuade;” Av. hak-, hacaiti “to attach oneself to, to join;” cf. Skt. sacate “accompanies, follows;” Gk. hepesthai “to follow,"; L. sequi “to follow;” PIE *sekw-.

A metal-poor main-sequence star with spectral type later than M7 and luminosity class VI. They are population II dwarfs which appear less luminous than their solar metallicity counterparts due to the dearth of metals in their atmospheres. Subdwarfs are
halo members with high proper motions and large heliocentric velocities. They are important tracers of the chemical enrichment history of the Galaxy and belong to the first generation of stars formed in the Galaxy (at least 10 billion years old).

See also: → sub-; → dwarf.

A star with a lower absolute magnitude than a normal giant star of its → spectral type. It is a star that has exhausted the hydrogen at its center and is evolving into a → red giant. Subgiants are luminosity class IV.

See also: → sub-; → giant.

1. Something that is being discussed, examined, or otherwise dealt with.
   

2. A branch of learning that forms a course of study.
   

3. Philosophy: That which thinks, feels, perceives, intends, as contrasted with the objects of thought, feeling, etc.
   

4. Grammar: The part of a sentence or clause referring to the person or thing that does or causes the action of a verb. In English, the subject is typically a noun (“The cat …”), a noun phrase (“His father’s first trip …”), or a pronoun (“It …”).

Etymology (EN): M.E. suget, from O.Fr. suget, subget “a subject person or thing,” from L. subjectus “placed beneath, inferior, open to inspection,”
noun use of p.p. of subicere “to place under,” from → sub-“under” + combining form of jacere “to throw,“from PIE base *ye- “to do” (cf. Gk. iemi, ienai “to send, throw,” Hitt. ijami “I make”).

Etymology (PE): Darâxt “thing drawn in, under” from dar- + âxt. The prefix dar-, from preposition dar “in, into, within; on, upon, above; of, about, concerning;” from Mid.Pers. andar “in, into, within,”
→ inter-.
The second component âxt, contraction of âxté, p.p. of âxtan, variants âhixtan, âhiz- “to draw (a sword),” âhanjidan “to draw up, pull, extract,” Mid.Pers. âhixtan, âhanjitan “to draw out, pull up, extract,” Av. θanj- “to draw, pull, drive;” Proto-Iranian
*θanj-.
Karin, from Sogd. karênê (variant kunênê) “doer, maker,” from kar-, kardan “to do, to make,” → -or.

1. That which depends upon the personal or individual, especially where it is supposed to be an arbitrary expression of private taste, in contrast with the objective.
   

2. Grammar: Pertaining to or constituting the subject of a sentence.

See also: Adjective of → subject.

1. The state or quality of being → subjective. Contrasted with → objectivity.
   

2. The interpretation based on individual personal feelings and opinions rather than on external → facts.

See also: → subjective + → -ity.

The process whereby a substance goes from a solid directly to a gaseous form.

Etymology (EN): From M.L. sublimationem (nominative sublimatio) “refinement,” literally “a lifting up, deliverance,” from L. sublimare “to raise, elevate,” from sublimis “lofty.”

Etymology (PE): Vâlâyeš, verbal noun from vâlâ “sublime, majestic,” may be a variant of bâlâ “up, above, high, elevated, height,” variants boland “high,” borz “height, magnitude” (it occurs also in the name of the mountain chain Alborz),
Lori dialect berg “hill, mountain;” Mid.Pers. buland “high;” O.Pers. baršan- “height;” Av. barəz- “high, mount,” barezan- “height;” cf. Skt. bhrant- “high;” L. fortis “strong” (Fr. & E. force); O.E. burg, burh “castle, fortified place,” from P.Gmc. *burgs “fortress;” Ger. Burg “castle,” Goth. baurgs “city,” E. burg, borough, Fr. bourgeois, bourgeoisie, faubourg); PIE base *bhergh- “high.”

A star that is less luminous than a main-sequence star of the same spectral type.

See also: → sub-; → luminous; → star.

(Adj.) Located, occurring, operating, or living beneath the surface of the → sea.

See also: → sub- + → marine.

Geology: A long, steep elevation of the deep sea floor.

See also: → submarine; → ridge.

Hydrology: A freshwater spring that emerges off the seashore.

See also: → submarine; → spring.

1. To sink or plunge under water or beneath the surface of any enveloping medium.
   

2. To cover or overflow with water; immerse (Dictionary.com).

Etymology (EN): From L. submergere, from → sub- + mergere “to dip, immerse;” probably by rhotacism from PIE *mezg- “to dip, plunge;” cf. Skt. majj- “to sink in water;” Lith. mazgoju “to wash.”

Etymology (PE): Marcidan, from Av. mraoc- “to float, submerge;” cf. Skt. mroc/mloc “to go down, set (of the Sun), to disappear, to hide;” Kurd., Laki, Nahâvandi, Bovir-Ahmadi mala- “swim,” Kurd. melâna “ship, boat,” melaq “wave” may be related to this Av. form.

Of or pertaining to scales smaller than millimeter.

See also: → sub-; → millimeter.

The study of astronomical objects with → submillimeter waves. As with millimeter-wave astronomy, this part of the spectrum is rich in lines emitted by interstellar molecules and dust.

See also: → submillimeter; → astronomy.

A member of an extremely luminous population of → high-redshift galaxies which are detected in → submillimeter waves (→ flux density at 850 μm ≥ 3 - 5 mJy). SMGs are powered primarily by star formation rather than an → active galactic nucleus (AGN). Because of their high → dust content, these galaxies emit almost
all of their luminosity in the infrared, with a → bolometric luminosity ranging from 10¹²-10¹³ → solar luminosities. As such, SMGs resemble → ultraluminous infrared galaxies (ULIRGs), which are almost exclusively → merging galaxies. Indeed, many observations support a → merger origin for SMGs (see, e.g. C.C. Hayward et al. 2011 and references therein, astro-ph/1101.0002).

See also: → submillimeter; → galaxy.

That part of the → electromagnetic radiation with a → wavelength beyond 300 → microns.

See also: → submillimeter; → radiation.

An electromagnetic wave having wavelengths less than one millimeter (frequencies greater than 300 gigahertz).

See also: → millimeter; → wave.

An act or instance of submitting. The condition of having submitted. → submit

See also: Verbal noun of → submit.

To present for the approval, consideration, or decision of another or others. For example, to submit a research paper for publication, to submit an observing proposal.

Etymology (EN): From L. submittere “to yield, lower, let down, put under, reduce,” from → sub- “under” + mittere “to let go, send.”

Etymology (PE): Dar sepordan, dar sepârdan “to yield, surrender, give in,” from dar “in, into” (→ in-)

• sepordan/sepârdan “to give in charge, entrust to, deposit with;” ultimately Proto-Iranian *spar- “to hand over, entrust.”

A proof that occurs within the context of a larger proof

See also: → sub-; → proof.

Describing a system or situation for which the → Lorentz factor, γ, is much smaller than 1. See also → ultrarelativistic.

See also: → ultra- + → relativistic

1. To pledge, as by signing an agreement, to give or pay (a sum of money) as a contribution, gift, or investment.
   

   2. To obtain or have a subscription to a publication, concert series, service, etc.
      

   3. To give one’s consent.
      

   4. To sign one’s name to a document (Dictionary.com).

Etymology (EN): → sub- + scribe, → inscribe.

Etymology (PE): Zirveštan, from zir-, → sub-,

• veštan, visidan, → inscribe.

1. Math.: An → index (a digit or symbol) written under and to the right of a letter for representing terms in a → sequence or → series,
   or indicating variable components in → tensor analysis.
   → superscript.
   

2. Chemistry: Such a number occurring in a chemical formula.

Etymology (EN): From L. subscriptus, p.p. of subscribere “to write underneath,”
from → sub- “underneath” + scribere “to write,” → describe.

Etymology (PE): Zirnevešt, from zir-, → sub-, + nevešt “written,” from neveštan, nevis- “to write;” Mid.Pers. nibištan, nibes- “to write;” Av./O.Pers. nī- “down; in, into,” → ni- (PIE), + paēs- “to paint; to adorn,” paēsa- “adornment” (Mid.Pers. pēsīdan “to adorn”); O.Pers. pais- “to adorn, cut, engrave” (Mod.Pers. pisé “variegated”); cf. Skt. piśáti “adorns; cuts;” Gk. poikilos “multicolored;” L. pingit “embroiders, paints;” O.C.S. pisati “to write;” O.H.G. fēh “multicolored;” Lith. piēšti “to draw, adorn;” PIE base *peik- “colored, speckled.”

1. A sum of money given or pledged as a contribution, payment, investment, etc.

   2. The right to receive a periodical for a sum paid, usually for an agreed number of issues (Dictionary.com).

See also: → subscribe; → -tion.

A set of elements wholly contained in another set. If each element of a set A belongs to a set B, A is called a subset of B, written A ⊂ B or B ⊃ A and read “A is contained in B” or “B contains A” respectively.

See also: → sub- + → set.

A set of electrons with the same angular momentum quantum number, denote l. The number of electrons permitted in a subshell is equal to 2l + 1.

See also: → sub- + → shell.

The point of the surface of a celestial body (including the Earth) at which the Sun is directly overhead at a particular time.

See also: → sub-; → solar; → point.

Describing a speed that is less than the speed of sound in the medium concerned. → supersonic.

See also: → sub-; → sonic.

A flow in which the velocity of the constituting particles never exceeds that of sound in the same fluid. Also called subcritical flow.

See also: → subsonic; → flow.

1. That of which a thing consists; physical matter or material.
   
2. Physics: A species of matter, commonly homogeneous, that occurs in macroscopic amounts.
   
3. Philo.: That by virtue of which a thing has its determinate nature, which makes it what it is, as distinguished from something else.

Etymology (EN): M.E., from O.Fr. substance, from L. substantia “being, essence, material,” from substans, pr.p. of substare “to stand under or be present,” from → sub- “up to, under” + stare “to stand,” cognate with Pers. istâdan “to stand,” as below.

Etymology (PE): Zirist, literally “to stand under,” from zir-, → sub-,

• ist “to stand; to be standing, “from istâdan “to stand;” Mid.Pers. êstâtan; O.Pers./Av. sta- “to stand, stand still; set;” Av. hištaiti; cf. Skt. sthâ- “to stand;” Gk. histemi “put, place, weigh,” stasis “a standing still;” L. stare “to stand;” Lith. statau “place;” Goth. standan; PIE base *sta- “to stand.”

Grammar: A word or word group functioning syntactically as a noun. Substantives include nouns and → nominals.

Etymology (EN): M.E., from L.L. substantivus “of substance or being,” from L. substantia “being, essence, material,” → substance, contraction of “noun substantive” from L. nomen substantivum (“independent noun”) as opposed to nomen adiectivum “noun adjective” (“dependent noun”).

Etymology (PE): Ziristin, from zirist, → substance, + -in a suffix of relation.

1. Pertaining to a class of objects with a mass less than 8 percent that of the Sun.
   

2. → substellar point.

See also: → sub- + → stellar.

The mass limit below which → hydrogen fusion cannot take place, and the cloud collapse cannot lead to the formation of a star. The limit is 0.075 → solar masses,
corresponding to about 80 Jupiter masses.

See also: → substellar; → limit.

An object with a mass too small to sustain the → proton-proton chain and thus become a true star. See → brown dwarf.

See also: → substellar; → object.

The point on the Earth, or other body, at which a particular star is directly overhead at a given time.

See also: → substellar; → point.

The fact or condition, for an object, of not being capable to sustain the → hydrogen fusion because of its low mass (less than 0.08 → solar masses).

See also: → substellar + → -ity.

A coherent component of a larger system.

See also: → sub-; → system

To be opposite and delimit the extent of an angle or side of a geometric figure.

Etymology (EN): From L. subtendere “to stretch beneath,” from → sub-

• tendere “to stretch,” cognate with Pers. târ “string,” tanidan “to weave,” as below.

Etymology (PE): Zirtânidan from zir-, → sub-, + tânidan from tân “thread, warp of a web,” tâl “thread” (Borujerdi dialect), târ “thread, warp, string,”
related to tur “net, fishing net, snare,” from tanidan, tan-
“to spin, twist, weave;” Mid.Pers. tanitan; Av. tan- “to stretch, extend;” cf. Skt. tan- to stretch, extend;" tanoti “stretches,” tántra- “warp; essence, main point;” Gk. teinein “to stretch, pull tight;” L. tendere “to stretch, as above; Lith. tiñklas “net, fishing net, snare,” Latv. tikls “net;” PIE base *ten- “to stretch.”

An angle whose two sides pass through the endpoints of an arc.

See also: Subtended p.p. of → subtend; → angle.

The point on the surface of a celestial body where the star is perceived to be directly overhead (in zenith). The sublunar point and subsolar point are the equivalent points for the Moon and Sun, respectively.

See also: → sub-; → terrestrial.

Fine or delicate in meaning or intent.

Etymology (EN): M.E. sotil, from O.Fr. sotil, soutil, subtil “adept, adroit; cunning, wise; detailed,” from L. subtilis “fine, thin, delicate, finely woven,” from → sub- “under” + -tilis, from tela “web, net, warp of a fabric,” → texture.

Etymology (PE): Naqz “subtle, elegant, beautiful, excellent, good.”

To take one number away from another; deduct. To perform the arithmetic operation of → subtraction.

Etymology (EN): From L. subtractus, p.p. of subtrahere “to draw from beneath, take away, draw off,” from → sub- “from under” + trahere “to pull, draw.”

Etymology (PE): Zirkaršidan, literally “to draw beneath,” from zir-, → sub-, + karšidan “to draw, pul, drag,” variant of kašidan “to draw, protract, trail, drag, carry;”
Av. karš- “to draw; to plow,” karša- “furrow;” Proto-Iranian *kerš-/*xrah- “to draw, plow;” cf. Skt. kars-, kársati “to pull, drag, plow;”
Gk. pelo, pelomai “to move, to bustle;” PIE base k^wels- “to plow.”
Kâhidan, → decrease.

The operation of finding the difference between two numbers or quantities.

See also: Verbal noun of → subtract.

1. Constituting or involving → subtraction.
   

2. Math.: Indicating or requiring subtraction; having a → minus sign.

See also: → subtract; → -ive.

Color produced by mixing pigments rather than light. Mixing all of the subtractive colors together results in the color black. See also → additive color.

See also: → subtractive; → color.

A special type being part of a more general type, e.g. subtype 2 among G type stars. → subclass.

See also: → sub-; → type.

1. To happen or terminate according to desire; turn out successfully; have the desired result.
   

2. To accomplish what is attempted or intended (Dictionary.com).

Etymology (EN): M.E. succeden, from O.Fr. succeder “to follow on” and directly from L. succedere “come after, follow after; go near to; come under; take the place of,” also “go from under, mount up, ascend,” hence “get on well, prosper, be victorious,” from → sub- “next to, after” + cedere “to go, move” → process.

Etymology (PE): Kâmyâbidan, back formation from kâmyâbi, → success.

1. The favorable or prosperous termination of attempts or endeavors; the accomplishment of one’s goals.
   

2. A performance or achievement that is marked by success, as by the attainment of honors (Dictionary.com).

Etymology (EN): From L. successus “an advance, a coming up; a good result, happy outcome,” noun use of p.p. of succedere “come after,” from suc-, → sub-, + ceder “to go, move,” → process.

Etymology (PE): Kâmyâbi, literally “acquiring, obtaining, finding one’s desire, wish,” from kâm “desire, wish,” → despite, + yâbi, from yâftan “to obtain, find,” → interpolation.

1. Achieving or having achieved success.
   

2. Resulting in or attended with success.

See also: → success + -ful a suffix meaning “full of, characterized by.”

Following in order or in uninterrupted sequence; e.g. → method of successive approximations.

Etymology (EN): M.E. from M.L. successivus, from
successus, p.p. of succedere “come after, go near to,” from → sub- “next to, after” + cedere “to go, move.”

Etymology (PE): Peyâpey “successive,” from pey “after; step,” related to pâ “foot” (Mid.Pers. pâd, pây, Av. pad-, Skt. pat, Gk. pos, gen. podos, L. pes, gen. pedis, P.Gmc. *fot, E. foot, Ger. Fuss, Fr. pied; PIE *pod-/*ped-) + -â- epenthetic vowel + pey, as explained.

The table sugar with chemical formula C₁₂H₂₂O₁₁, which is a particular type of → sugar compounds.

See also: From → sugar + -ose a suffix borrowed from L. denoting “full of, given to.”

1. The state or fact of being sufficient.
   

2. A sufficient number or amount.

See also: → sufficient + -cy a suffix used to form abstract nouns.

1. Adequate for the purpose; enough.
   

2. Logic, Math.: A condition which, if true, guarantees that a result is also true. However, the result may also be true if the condition is not met.
   → if and only if.

Etymology (EN): M.E., from O.Fr. sufficient, from L. sufficiens, pr.p. of sufficere “supply, suffice,” from sub “up to,” → sub-, + root of facere “to make,” → fact.

Etymology (PE): Basandé “sufficient, complete, worthy,” from *basidan, from bas “many, much,” → multi-.

An → affix that follows the base to which it is added.

Etymology (EN): N.L. from suffixus, p.p. of suffigere “to attach on top of,” from suf-, variant of → sub- + figere “fasten.”

Etymology (PE): Pasvand, from pas- “after, behind,” → back-,

• vand, → affix.

1. A family of simple, often sweet, compounds consisting of → carbon, → hydrogen, and → oxygen obtained particularly from sugarcane and sugar beets. The sugar family includes glucose, sucrose, lactose, fructose, maltose, lactose,
   and galactose. Sugar molecules have been detected in
   → interstellar medium  → molecular clouds.
   

2. Specifically, → sucrose.

Etymology (EN): M.E. sugre, sucre, from O.Fr. sucre, from M.L. succarum, from Ar. sukkar, from Pers. shakar, from Skt. šárkarā- “ground or candied sugar,” originally “grit, gravel.”

Etymology (PE): Šekar, Mid.Pers. šakar, ultimately from Skt. šárkarā-, as above.

To mention or introduce (an idea, proposition, plan, etc.) for consideration or possible action: The architect suggested that the building be restored (Dictionary.com).

Etymology (EN): From L. suggestus, p.p. of suggerere “to bring under, bring up,
lay beneath; afford, supply,” from → sub- +
gerere “to bring, carry,” of unknown origin.

Etymology (PE): From pišnehâd, from piš “before,” → pre-,

• nehâd, past stem of nehâdan “to place, put,” → position.

1. The act of suggesting.
   

2. The state of being suggested.
   

3. Something suggested, as a piece of advice (Dictionary.com).

See also: Verbal noun of → suggest.

Also sulphur, a nonmetallic chemical element; symbol S. Atomic number 16; atomic weight 32.06; melting point 112.8°C (rhombic), 119.0°C (monoclinic), about 120°C (amorphous); boiling point 444.674°C; specific gravity at 20°C, 2.07.

Etymology (EN): M.E. sulphur, from L. sulpur, sulphur, sulfur “brimstone;” maybe from Skt. sulveri “eneny of copper,” as copper loses all its properties when heated with sulfur. It was known from prehistoric times. In 1809, the French chemists, Louis-Joseph Gay-Lussac and Louis-Jacques Thenard proved the elemental nature of sulfur.

Etymology (PE): Gugerd, from Mid.Pers. gôgird “sulfur,” gôgirdômand “sulfurous.”

1a) Math.: The number or quantity that is the result of adding two or more numbers or quantities.

1b) A particular amount or total, especially of money.

2a) To combine into an aggregate or total (often followed by up).

2b) To ascertain the sum of, as by addition (Dictionary.com).

Etymology (EN): M.E. summe, from O.Fr. summe, from L. summa “total number, whole, essence, gist,” noun use of feminine of summus “highest,” superlative of superus, → super-.

Etymology (PE): Bazâv, from Mid.Pers. abzây-, abzudan (Mod.Pers. afzâ-, afzudan) “to increase;” Parthian abigâw- “to increase;” Sogd. β(ə)žāw “to grow, increase;” O.Pers. abiyajāv- “to increase, add to, promote,” from abi-, aiby- “in addition to; to; against” + root jav- “press forward;” Av. gu- “to increase;” Khotanese gvāna- “growth;” Skt. jav- “to press forward, impel quickly, excite,” javate “hastens”).

To make a summary of; state or express in a concise form.

See also: → summary + → -ize.

1. A brief account giving the main points of something.
   

2. Covering the main points; comprehensive.

Etymology (EN): From L. summarium “an epitome, abstract, summary,” from summa “totality, gist,” → sum, + → -ary.

Etymology (PE): Bazâvak, from bazâv, present stem of bazâvidan, → sum, + -ak relation suffix.

The season that starts when the Sun, during its apparent yearly motion, attains the celestial longitude 90 degrees in the Northern Hemisphere and 270 degrees in the Southern Hemisphere. The current length of the summer season, around the epoch 2000, is 93.65 days.

Etymology (EN): M.E. sumer, from O.E. sumor (cf. O.S., O.N., O.H.G. sumar, O.Fris. sumur, M.Du. somer, Du. zomer, Ger. Sommer), from PIE base *sem- “summer;”
cf. Av. ham- “summer;” Mid.Pers. hāin “summer;”
Skt. sámā- “half-year, season;” Arm. am “year,” amarn “summer;” O.Ir. sam “summer;” O.Welsh ham “summer.”

Etymology (PE): From Mid.Pers. tâpistân, ultimately from Proto-Iranain *tap-stā- “hot, heat season, time, place.” The first component
*tap- “to shine, radiate;” cf. Mod.Pers.
tâbidan, variants tâftban “to shine,” tafsidan “to become hot;” Mid.Pers. tâftan “to heat, burn, shine;” taftan “to become hot;” Parthian t’b “to shine;”
Av. tāp-, taf- “to warm up, heat,” tafsat “became hot,” tāpaiieiti “to create warmth;” cf. Skt. tap- “to heat, be/become hot; to spoil, injure, damage; to suffer,” tapati “burns;” L. tepere “to be warm,” tepidus “warm;” PIE base *tep- “to be warm.”

The second component *stā- “to stand; to set; to place;” a suffix of “place, land, country” and in rare cases “time;” examples:

“Afghanistan;” ترکستان “Turkistan;” پاکستان “Pakistan;”

region, highland;"

From Mid.Pers. -stân, -istân. Examples: gôstân (گاوستان) “cowshed;” šapistân (شبستان) “dormitory;” tâpistân “summer;” zamistân “winter.” From O.Pers. stāna- “place;”
Av. stāna-, as in gaostāna- (Mid.Pers. gôstân, as above) “cowshed;” from Proto-Iranian *stāna-.
This suffix is related to O.Pers./Av. base sta- “to stand;” Mod.Pers. istâdan (ایستادن) “to stand;” cf. Skt. sthā- “to stand,” sthāna- “standing;” Gk. histemi “to put, place,” stasis “standing still;” L. stare “to stand;” Goth. standan; O.H.G. stantan; O.E. standan; E. stand; PIE base *sta- “to stand.”

The moment in the northern hemisphere when the → Sun attains its highest → declination of 23°26’ (or 23°.44) with respect the → equator plane. It happens when the Earth’s axis is orientated directly toward the Sun, on 21 or 22 June. During the northern solstice the Sun appears to be directly overhead at noon for places situated at → latitude 23.44 degrees north, known as the → tropic of Cancer. The summer solstice can occur at any moment during the day. Two successive summer solstices are shifted in time by about 6 h. The summer solstice in the northern hemisphere is the → winter solstice in the southern hemisphere.

See also: → summer; → solstice.

The triangular shape formed by the three bright stars → Altair, → Deneb, and → Vega on the northern hemisphere’s → celestial sphere, particularly visible during the summer months.

See also: → summer; → triangle.

The star that governs the solar system. It is a yellow main-sequence star of spectral type G2, shines with apparent magnitude -26.74, and has an absolute magnitude of +4.83. The Sun is 4.6 billion years old and lies 27,000 light-years from the Galactic center.

Etymology (EN): O.E. sunne; cf. O.N., O.S., O.H.G. sunna, M.Du. sonne, Du. zon, Ger. Sonne, Goth. sunno; cognate with Pers. xor, hur, as below.

Etymology (PE): Xoršid “sun,” originally “sunlight,” from xor “sun,” variant hur; Mid.Pers. xwar “sun;” Av. hū-, hvar- “sun;” cf. Skt. surya-, Gk. helios, L. sol, cognate with E. sun, as above;
PIE base *sawel- “sun” + šid “light, sunlight;” from Mid.Pers. šêt “shining, radiant, bright;” Av. xšaēta- “shining, brilliant, splendid, excellent.”

→ light pillar.

See also: → sun; → pillar.

A comet that passes extremely close to the Sun’s → surface, in some cases within a few thousand kilometres of the Sun’s surface.
The Great Comet of 1965, Ikeya-Seki, was a member of the sun-grazer family, coming within about 650,000 km of the Sun’s surface. Passing so close to the Sun, sun-grazers are subjected to destructive → tidal forces along with intense solar heat which can completely evaporate them during such a → close approach.

See also: → Sun; → grazer.

An instrument for showing apparent solar time by the position of the shadow cast by an indicator. → gnomon.

Etymology (EN): From → Sun + -dial M.E. instrument for telling time by the Sun’s shadow, presumably from M.L. dialis “daily,” from L. dies “day;” → diurnal.

Etymology (PE): Sâ’at-e âftâbi, from sâ’at, → clock,

• âftâb, → Sun.

The light of the Sun.

Etymology (EN): → sun; → light.

Etymology (PE): Âftâb, “sun(shine);” Mid.Pers. âftâp; Proto-Iranian *abi-tap-, from *abi- “to, upon, against” (O.Pers./Av. abiy-/aiwi-
“to, upon, against;” Skt. abhi-, Gk. amphi-) + *tap- “to shine” (Mod.Pers. tâbidan, variants tâftban “to shine,” tafsidan “to become hot;” Mid.Pers. tâftan “to heat, burn, shine;” taftan “to become hot;” Parthian t’b “to shine;”
Av. tāp-, taf- “to warm up, heat,” tafsat “became hot,” tāpaiieiti “to create warmth;” cf. Skt. tap- “to heat, be/become hot; to spoil, injure, damage; to suffer,” tapati “burns;” L. tepere “to be warm,” tepidus “warm;” PIE base *tep- “to be warm”).

The time at which the apparent upper limb of the rising Sun is on the astronomical horizon, that is when the true zenith distance, referred to the center of the Earth, of the central point of the disk is 90°50’, based on adopted values of 34’ for horizontal refraction and 16’ for the Sun semidiameter.

See also: → Sun; → rise.

The time at which the apparent upper limb of the setting Sun is on the astronomical horizon, that is when the true zenith distance, referred to the center of the Earth, of the central point of the disk is 90°50’, based on adopted values of 34’ for horizontal refraction and 16’ for the Sun semidiameter.

See also: → Sun; → set.

An area seen as a dark patch on the Sun’s surface. Sunspots appear dark because they are cooler (of about 4000 °C) than the surrounding → photosphere (about 6000 °C). They range in size from a few hundred kilometers to several times the Earth’s diameter and last from a few hours to a few months. Very small sunspots are called → pores. The number of sunspots
varies from maximum to minimum in about 11 years, the
→ sunspot cycle. Their appearance during a cycle follows the → Sporer law. A typical spot has a central → umbra surrounded by a → penumbra, although either features can exist without the other. Sunspots are associated with strong magnetic fields of 0.2 to 0.4 → tesla. A given sunspot has a single magnetic → polarity. The opposite polarity may be found in other sunspots or in the bright and diffuse → facular region adjacent to the sunspot. The first recorded naked-eye sightings of sunspots were by Chinese astronomers in the first century B.C.
Johannes Fabricius (1587-1617) was the first to argue that sunspots are areas on the solar surface.

See also: → Sun; → spot.

→ solar cycle.

See also: → sunspot; → cycle.

Periods of time when the → relative sunspot number is low. These periods of time occur approximately every 11 years and represent the minimum in the → sunspot cycle.

See also: → sunspot; → minimum.

A quantity which gives the number of sunspots
at a given time. It is defined by the relationship R = k(10g + f), where R is the sunspot number, k is a constant depending on the observation conditions and the instrument used, g is the number of the groups and f is the number of individual spots that can be counted. Also called the
→ Wolf number and → relative sunspot number.

See also: → sunspot; → number.

The loss of energy by high-energy electrons in a → galaxy cluster, which distorts the → cosmic microwave background (CMB) radiation through → inverse Compton effect. When photons from the CMB radiation travel through a hot plasma (with a temperature of around 10⁸ K), in which bathe a galaxy cluster, they collide with energetic electrons and some of the energy of the electrons is transferred to the low energy CMB photons. If we look at the CMB radiation through such a plasma cloud, we therefore see fewer microwave photons than we would if the cloud were not there.

See also: Named after Rashid Sunyaev (1943-) and Yakov Borisovich Zel’dovich (1914-1987), Russian astrophysicists; → effect.

Same as → perigee full Moon.

See also: → super-; → Moon.

A group of hundreds to thousands of very young stars packed into an unbelievably small volume of a few parsecs in size. These objects represent the youngest stage of → massive star cluster evolution yet observed. The most massive and dense SSCs, with ages less than 10⁶ years, may be proto globular clusters. SSCs are thought to dissolve within 10 million years and merge into the field star population.

See also: → super; → star;
→ cluster.

A prefix occurring originally in loanwords from Latin, with the basic meaning “above, beyond.”

Etymology (EN): L. adverb and preposition super “above, over, on the top (of), beyond, besides, in addition to,” from PIE base *uper “over,” cognate with Pers. abar-, as below.

Etymology (PE): Mid.Pers. abar (Mod.Pers. bar- “on, upon, up”); O.Pers. upariy “above; over, upon, according to;” Av. upairi “above, over,” upairi.zəma- “located above the earth;” cf. Gk. hyper- “over, above;” L. super-, as above; O.H.G. ubir “over.”

A star whose mass exceeds the → canonical upper limit of the stellar → initial mass function (Kroupa et al. 2012, arXiv:1112.3340).

See also: → super-; → canonical; → star.

A superluminous → Type Ia supernova which is characterized by a bright → light curve peak, a slow light curve evolution during the photospheric phase, and moderately low ejecta velocities. Modeling suggests ejecta masses far in excess of the → Chandrasekhar limit of mass for non-rotating → white dwarfs and the production of about 1.5 Msun of ⁵⁶Ni. This precludes the interpretation of these events as thermonuclear explosions of Chandrasekhar-mass white dwarfs.

See also: → super-; → Chandrasekhar limit.

An → extrasolar planet more massive than the Earth but less massive than 10 → Earth masses. The first discovered super-Earth orbits an M4 V star named GJ 876. Its estimated mass is 7.5±0.7 Earth masses and it has an orbital period of 1.94 days. It is close to the host star, and the surface temperature is calculated to lie between 430 and 650 K (Rivera et al. 2005, ApJ 634, 625).

See also: → super-; → Earth.

A → stellar wind accelerated by radiation pressure in the continuum from a star with a luminosity above the → Eddington limit.

See also: → super-; → Eddington limit; → wind.

A very → metal-rich star whose iron → metallicity, [Fe/H], exceeds 0.20 → dex. Examples include HD 32147, HD 121370, and HD 145675 (Feltzing & Gonzalez, 2001, A&A 367, 253).

See also: → super-; → metal; → rich; → star.

A condition in which there is an excess of the actual temperature gradient over the → adiabatic temperature gradient corresponding to the same pressure gradient. A region with superadiabatic temperature gradient is convectively unstable. → Hayashi forbidden zone.

See also: → super-; → adiabatic; → temperature; → gradient.

A cavity hundreds of light-years across filled with a hot gas blown into the interstellar medium by multiple supernovae and stellar winds. Examples are the Local Bubble in the Orion Arm of the Milky Way and the N44 Superbubble in the Large Magellanic Cloud.

See also: → super-; → bubble

1. An aggregation of clusters of galaxies (→ galaxy cluster). Superclusters are typically about one hundred million (10⁸) → light-years in diameter and contain tens of thousands of galaxies. Some examples are the → Local Supercluster, → Centaurus supercluster, → Laniakea supercluster, → Perseus-Pisces supercluster→ Shapley supercluster→ Virgo supercluster.
   

2. For stellar aggregations, → dynamical stream.

See also: → super-; → cluster

Grouping of galaxies in supercluster structure.

See also: → super-; → clustering

The phenomenon in which certain materials, when cooled to a sufficiently low temperature, lose all resistance to the flow of electricity.

See also: → super-; → conductivity

A material which shows almost perfect conductivity at temperatures approaching absolute zero.

See also: → super-; → conductor.

The process by which a liquid or a gas is cooled below the temperature at which a → phase transition should occur. For example, water can be cooled well below the → freezing point without freezing (as often happens in the upper atmosphere). The introduction of an → impurity or surface can trigger freezing.

See also: → super-; → cooling.

1. Thermodynamics: Describing a condition in which a substance has a temperature or pressure above its critical value of temperature or pressure.
   

2. Nuclear physics: Of or relating to an arrangement of → fissile material where more neutrons are being produced than are wasted and escape.

See also: → super-; → critical.

A fluid that is at a temperature and pressure above its thermodynamic critical point. In these conditions the substance acquires unique characteristics of density and mobility. Supercritical fluids exist deep inside some planets; for example, there is supercritical water deep inside the Earth.

See also: → supercritical; → fluid.

A → fluid that exhibits frictionless flow, very high heat → conductivity, and other unusual physical properties. For example, → liquid helium at the temperature about 2.17 K (→ lambda point) becomes a zero → viscosity fluid which will move rapidly through any pore in the apparatus. See also → helium II.

See also: → super-; → fluid

The phenomenon occurring in → liquid helium
(→ helium I) cooled below the → lambda point temperature of 2.17 K, whereby it flows freely with no measurable → friction and → viscosity.

See also: → super-; → fluidity.

Of or pertaining to a system composed of nearby groups and clusters of galaxies in the → local Universe. Se also → galaxy cluster.

See also: → super-; → galactic.

A spherical → coordinate system in which the → equator is the → supergalactic plane. Supergalactic longitude, SGL, is measured → counterclockwise from direction l = 137.37 deg, b = 0 deg (between 0 and 360 deg). The zero point for supergalactic longitude is defined by the intersection of this plane with the → Galactic plane. In the → equatorial coordinate system
(J2000) this is approximately 2.82 h, +59.5 deg. Supergalactic latitude, SGB, is measured from the supergalactic plane, positive northward and negative southward. The North Supergalactic Pole (SGB=90 deg) lies at galactic coordinates l = 47.37 deg, b = +6.32 degrees, corresponding to the equatorial coordinate system (J2000) 18.9 h, +15.7 deg.

See also: → supergalactic; → coordinate; → system.

→ supergalactic coordinate system.

See also: → supergalactic; → latitude.

→ supergalactic coordinate system.

See also: → supergalactic; → longitude.

The symmetry plane of the → Local Supercluster, where density of galaxies in our environment is the largest. The plane passes through the → Virgo cluster of galaxies, about which many of the brightest galaxies in the sky are concentrated. The supergalactic plane was recognized by Gérard de Vaucouleurs (1918-1995) in 1953 from the  → Shapley-Ames catalogue.

See also: → supergalactic; → plane.

A star with maximum intrinsic brightness and low density. The radius of a supergiant can be as large as 1000 times that of the Sun. See also → blue supergiant; → red supergiant; → yellow supergiant.

See also: → super-; → giant

A highly luminous → B[e] star with a luminosity greater than 10⁴L_sun. A number of such objects exist in the → Magellanic Clouds, e.g. LMC R126, R66, SMC R4, and R50. A likely example in our Galaxy is MWC 300.

See also: → supergiant; → B[e] star.

One of a number of large convective cells (about 15,000-30,000 km in diameter) in the solar photosphere, distributed fairly uniformly over the solar disk, that last longer than a day.

See also: → super-; → granulation; → cell.

A vapor that has been heated above its boiling point temperature corresponding to the pressure.

See also: → super-; → heat; → vapor.

The process in which a liquid is heated to a temperature higher than its boiling point, without boiling. Superheating is achieved by heating a homogeneous substance in a clean container, free of nucleation sites.

See also: → super-; → heating.

A radio receiver which uses the → superheterodyne technique.

See also: → super-; → heterodyne; → receiver.

The technique used in a radio receiver in which the frequency of an incoming signal is changed by adding it to a signal generated within the receiver to produce fluctuations or beats of a frequency equal to the difference between the two signals.
See also → mixer.

See also: → superheterodyne receiver; → technique.

An ion which is responsible for the existence of a strong → P Cygni profile observed in many early O stars. Since the → effective temperature of the star is too low to produce such an ion appreciably, the ion is termed a superion.

For example, the ion O⁵⁺ which is at the origin of a strong O VI λλ1031, 1038 P Cygni profile observed in many O stars. Similarly, the lines due to N V λλ1238, 1242 belong to the superion category, while in later spectral types C IV λλ1548, 1552 also falls into this category.

Initial modeling of the → ultraviolet line superions assumed the → stellar winds were smooth and homogeneous. However it is now generally accepted that the winds are (→ clumped wind), and this can have a profound influence on the formation of the superion profiles. We know that the strength of lines due to the superions is strongly influenced by the → interclump medium. Indeed, the interclump medium may be more important for producing the lines than are the clumps – this is simply a consequence of the higher ionization in the interclump medium which occurs because of its lower density (see D. John Hillier, 2020, https://www.mdpi.com/2075-4434/8/3/60/htm, and references therein).

See also: → super-; → ion.

Upper or situated higher up in rank, degree, etc.

Etymology (EN): M.E., from O.Fr., from L. superiorem (nominative superior) “higher,” comparative of superus “situated above, upper,” from super “above, over,” → super-.

Etymology (PE): Zabar, from Mid.Pers. azabar “above,” related to abar (Mod.Pers. bar- “on, upon, up”); O.Pers. upariy “above; over, upon, according to;” Av. upairi “above, over,” upairi.zəma- “located above the earth;” cf. Gk. hyper- “over, above;” L. super-, as above; O.H.G. ubir “over” + -in comparative suffix.

The conjunction of a planet with the Sun which occurs when the planet is beyond the Sun. → inferior conjunction.

See also: → superior; → conjunction.

The meridian transit of a star between the celestial pole and the south point of the horizon. Same as → upper culmination. → inferior culmination.

See also: → superior; → culmination.

A planet whose orbit lies outside that of the Earth. The superior planets are Mars, Jupiter, Saturn, Uranus, and Neptune. → planet.

See also: → superior; → planet.

Apparent proper motion exceeding the velocity of light seen toward certain astronomical objects, such as the jets of radio galaxies and quasars. However, these jets are not actually moving at speeds in excess of the speed of light: the apparent superluminal motion is a projection effect caused by objects moving near the speed of light and at a small angle to the line of sight.

Etymology (EN): → super-; luminal, from → lumen; → motion.

Etymology (PE): Jonbeš, → motion; abar→ super-; nur, → light.

The quality of an object whose luminosity exceeds a certain value.

See also: → super-; → luminous.

A → supernova with an → absolute magnitude of about -22 in optical. Examples of these newly discovered SNe include SN 2006gy, SN 2005ap, and SNe 2003ma. The nature of these objects is poorly known. Some of them are powered by the circumstellar interaction, or by the shock breakout from the dense circumstellar medium, as suggested by the presence of narrow emission lines in superluminous → Type II-N supernovae. It is also argued that superluminous SNe could be powered by a large amount of ⁵⁶Ni which is synthesized as a result of energetic → core-collapse supernovae. Other scenarios include the interaction between shells ejected by the pulsational → pair-instability. See, e.g. Tanaka et al. 2012, MNRAS 422, 2675, arXiv:1202.3610, and references therein.

See also: → superluminous; → supernova.

Having a mass highly exceeding a certain limit. → supermassive black hole, → supermassive neutron star, → supermassive star.

See also: → super-; → massive.

A → black hole of tremendous mass, equivalent to those of millions or even billions of stars, which is believed to exist and occupy the centers of many galaxies. The supermassive black hole residing in the center of our → Milky Way Galaxy is the object → Sgr A* with a mass of 4 x 10⁶→ solar masses within a radius of 100 → astronomical units.

See also: → supermassive; → black hole.

A → neutron star of mass above the typical value that is temporarily prevented from → collapseing into a → black hole because of its rapid → rotation.

See also: → supermassive; → neutron; → star.

A star with an initial mass over about 120 solar masses. The existence of such stars is the present Universe is not confirmed. Such stars were proposed as an explanation for very bright O type stars in the Large Magellanic Cloud, but these are now known to be clusters of ordinary O stars.
→ very massive star; → massive star.

See also: → supermassive; → star.

Same as → perigee full Moon.

See also: → super-; → moon.

A generalization of the concept of multiplet to the case when there are several quantum numbers that describe the quantum-mechanical states.

See also: → super-; multiplet.

1. Of, pertaining to, or being above or beyond what is natural; unexplainable by natural; abnormal.
   

2. Of, pertaining to, characteristic of, or attributed to God or a deity (Dictionary.com).

See also: → super-; → natural.

Belief in the doctrine of supernatural or divine agency as manifested in the world, in human events, religious revelation, etc. (Dictionary.com).

See also: → super-; → naturalism.

A violent stellar explosion which blows off all or most of the star’s material at high velocity leaving a compact stellar remnant such as a → neutron star or → black hole. At → maximum light, the supernova can have → luminosity about 10⁸ or 10⁹ times the → solar luminosity. The phenomenon results from the later evolution of stars when an instability sets in
the core following the → nucleosynthesis of → iron. In → massive stars, the supernova occurs when the star has used up all its available → nuclear fuel and it reaches a lower energy state through → gravitational collapse to form a more compact object. In → white dwarfs forming → binary systems, → accretion of mass onto the surface of a neutron star can be sufficient to take the star over the upper mass limit for stability as a white dwarf. Consequently, the white dwarf collapses in a → supernova explosion to form a neutron star.
There are several → supernova types.

See also: → super-; → nova.

A star which according to observational data could become a supernova.

See also: → supernova; → candidate.

The material ejected by a → supernova explosion.

See also: → supernova; → ejecta.

The total amount of energy liberated by a → supernova. A typical supernova radiates between 10⁵¹ and 10⁵²  → erg, or 10^44-45 J (→ joules).

See also: → supernova; → energy.

The very short and violent phenomenon that occurs when a star undergoes → core collapse or → thermonuclear runaway.

See also: → supernova; → explosion.

1. The process whereby the energy and matter contained in a → supernova are injected into the → interstellar medium after the → supernova explosion. The → thermal energy injected into the ISM serves to → suppress → star formation, while → heavy elements → nucleosynthesized inside SNe tend to enhance star formation.
   

2. The matter thus injected.

See also: → supernova; → feedback.

A brilliant burst of light that would suggest a → supernova explosion, but analysis of the star’s → light curve, → spectrum, and → luminosity rules it out as a genuine supernova. Energetic → outbursts of → massive stars are often labeled as “supernova impostors” (Van Dyk et al. 2000). Many of these giant eruptions are spectroscopically similar to → Type II-n supernovae and thus receive a supernova (SN) designation, but are later recognized as subluminous or their spectra and light curves do not develop like true supernovae. Consequently, they are often referred to as “supernova impostors.” These impostors or giant eruptions are examples of high → mass loss episodes apparently from evolved massive stars. Authors often refer to them as → Luminous Blue Variables (LBVs), but these giant eruptions are distinctly different from LBV/→ S Doradus variability in which the star does not increase in luminosity and the eruption or maximum light can last for several years. The mechanisms triggering these events are not yet fully understood (see, e.g., Humphreys et al., 2016, arXiv:1606.04959v1).

See also: → supernova; → impostor.

The graph of luminosity as a function of time after a → supernova explosion. The → light curve goes up rapidly to a → peak luminosity, then decays away slowly over time, with different rates, depending on the → supernova type.

The temporal evolution of a supernova’s luminosity contains important information on the physical processes driving the explosion. The observed → bolometric light curves provide a measure of the total output of converted radiation of → Type Ia supernovae, and hence serve as a crucial link to theoretical models of the explosion and evolution.

See also: → supernova; → light; → curve.

A star which is at the origin of a supernova phenomenon.

See also: → supernova; → progenitor.

The body of expanding gas ejected at a speed of about 10,000 km s^-1
by a → supernova explosion, observed as a diffuse → gaseous nebula, often with a → shell-like structure. Supernova remnants are generally powerful → radio sources. The evolution of the SNR can be divided into different phases according to the dominant physical processes. Simplified models are made for the first stages, to get an idea of typical time scales, expansion velocities, and sizes. The three main phases are:

1. the → free expansion phase,
2. the → Sedov-Taylor phase, and
3. the → snowplow phase.

See also: → supernova; → remnant.

A → shock wave that forms when the inner → iron core (of ~ 0.5 Msun) → collapses until it reaches densities in excess of → nuclear density. At this point the pressure rises dramatically and resists further collapse. The homologous core bounces and drives out a shock wave that works its way through the remainder of the initial iron core. The small compressibility of nuclear matter halts the infall of the innermost core by an elastic collective bounce whose kinetic energy is almost immediately depleted by the → photodisintegration of heavy nuclei and the emission of → neutrinos.

See also: → supernova; → shock.

The classification of supernovae according to the presence or absence of the absorption lines of different chemical elements that appear in their spectra shortly after their explosion. Basically, supernovae come in two main types: those that have hydrogen (Type II, from a very massive star that blows up) and those that do not (Type I, due to thermonuclear runaways in a less massive star). Both types exhibit a wide variety of subclasses. Type Ia lacks hydrogen and presents a singly-ionized silicon (Si II) line at 6150 Å, near peak light. Type Ib has non-ionized helium (He I) line at 5876 Å, and no strong silicon absorption feature near 6150 Å. Type Ic shows weak or no helium lines and no strong silicon absorption feature near 6150 Å. Type II stars also have various subclasses. See also → Type I supernova, → Type Ia supernova, → Type Ib supernova, → Type Ic supernova, → Type II supernova, → Type II-L supernova, → Type II-n supernova, and → Type II-P supernova

See also: → supernova; → type.

Exceeding the usual or prescribed number; extra; additional.

Etymology (EN): L.L. supernumarius “excess, counted in over” (of soldiers added to a full legion), from L. super numerum “beyond the number,” → super- “beyond, over” + numerum, accusative of numerus, → number.

Etymology (PE): Faršomâr, from far- intensive prefix “much, abundant; elegantly;” also “above, upon, over; forward, along,” → pro-, + šomâr, → number.

An additional faint arc or series of arcs just
below the → primary rainbow. Supernumerary bows are caused by → interference and are more common toward the top of the bow.

See also: → supernumerary; → rainbow.

1. The act of placing upon; the state of being placed upon.
   

2. Math. The act of placing (one geometric figure) over another so that all like parts coincide.

Etymology (EN): → super- + → position.

Etymology (PE): Barhamneheš, from
bar- “on, upon, up” (Mid.Pers. abar; O.Pers. upariy “above; over, upon, according to;” Av. upairi “above, over,” upairi.zəma- “located above the earth;” cf. Gk. hyper- “over, above;” L. super-; O.H.G. ubir “over;” PIE base *uper “over”)

• -ham- “together, with,” → syn-, + neheš, → position.

1. Math.: The principle concerned with homogeneous and non-homogeneous → linear differential equations, stating that two or more solutions to a linear equation or set of linear equations can be added together so that their sum is also a solution.
   

2. One of the most fundamental principles of → quantum mechanics which distinctly marks the departure from classical concepts. It holds that any linear superposition of → wave functions is also a possible wave function. Simply put, the state of an object is all its possible states simultaneously, as long as we do not look to check. It is the measurement itself that causes the object to be limited to a single possibility. The superposition principle is rooted in the linearity of → Schrödinger’s equation. Hence if two solutions of the wave function, ψ₁ and ψ₂, are known, other solutions, of the form: ψ = a₁ψ₁ + a₂ψ₂ also represent possible states of the system.

See also: → superposition; → principle.

The process whereby the amount of → water vapor in the air exceeds that needed to → saturate. In other words, the condition of air in which the → humidity is above the level required for saturation at a given temperature (i.e. the → relative humidity is greater than 100%). When the temperature drops below freezing, this can lead to a situation where more water vapor is present in the air than the air can hold. At every temperature, there is a maximum amount of water vapor that can be supported in the air. The higher the temperature, the more water vapor can be accommodated. But if the air that is already at 100% relative humidity is cooled then it becomes supersaturated, and this situation is unstable. As a result, the excess water vapor crystallizes out, either into water droplets or directly into ice.

See also: → super-; → saturation.

An → index (a digit or symbol) written slightly above and to the right of a letter, such as for representing variable components in → tensor analysis. → subscript. The most common mathematical superscript is an → exponent. Other common superscripts are the single and double prime marks
indicating the → first derivative and → second derivative of a → function. See also → contravariant tensor.

Etymology (EN): → super- + script, → subscript.

Etymology (PE): Zabarneveš, from zabar- “above,” → superior

• nevešt “written,” → subscript.

Describing a speed that is greater than the → sound speed in the medium concerned. See also → Mach number, → subsonic.

See also: → super-; → sonic.

A class of theories that seek to unify the four fundamental forces of nature. It proposes symmetrical relationships linking fermions and bosons (particles of half integer spin, like electrons, protons, and neutrinos) with particles of integral spin (like photons and gluons).

See also: → super; → symmetry.

A galaxy that appears as an extraordinary thin and long figure
on the sky because of its → edge-on orientation, highly flattened stellar → disk, and absence of a → bulge component. Superthin galaxies are → gas-rich and have optically diffuse disks with little internal absorption, as well as low emission-line intensity ratios and slowly rising → rotation curves. They seem to be among the least evolved disk galaxies in the local Universe, having undergone only minimal dynamical heating, → star formation, and → angular momentum transport. Examples are: UGC 7321, UGC 3697, UGC 9242.

See also: → super-; → thin; → galaxy.

A galactic-scale wind driven by the collective effect of a large number of → supernovae and → winds from → massive stars occurring in the central region of a galaxy. Superwinds have been invoked, among other things, as the source by which the → intergalactic medium is provided with → enriched gas (see, e.g. Heckman et al. 1990, ApJS 74, 833).

See also: → super-; → wind.

A galaxy with → superwind characteristics. M 82 and NGC 4666 are among superwind galaxy candidates.

See also: → superwind; → galaxy.

1a) A thing added to something else in order to complete, reinforce, or extend it.

1b) A separation section added to a book, document, etc., to supply additional or later information, or the like.

2a) To complete, add to, or extend by a supplement.

2b) To form a supplement or addition to.

Etymology (EN): From L. supplementum “that which fills up, that with which anything is made full or whole, something added to supply a deficiency,” from supplere “to fill up, complete,” from → sub- “up from below” + plere “to fill;” cognate with Pers. por, as below.

Etymology (PE): Âporidan, from prefix â-

• por “full;” Mid.Pers. purr; O.Pers. paru- “much, many;” Av. parav-, pauru-, pouru-, from
  par- “to fill;” PIE *pelu- “full,” from *pel- “to be full;” cf. Skt. puru-; Gk. polus; P.Gmc. *fullaz (O.H.G. fol, Ger. voll, Goth. full, O.E. full).

Completing something or added as a supplement.

See also: → supplement; → -ary.

The angle that when added to a given angle makes 180°. → complementary angle.

See also: → supplementary; → angle.

1a) Something that serves as a foundation, prop, brace, or stay.

1b) The act or an instance of supporting.

2a) To bear or hold up (a load, mass, structure, part, etc.); serve as a foundation for.

2b) To uphold (a person, cause, policy, etc.) by aid, countenance, one’s vote, etc.; back (Dictionary.com).

Etymology (EN): M.E. supporten, from M.Fr. supporter, from L. supportare “convey, carry, bring forward,” from → sub- “up from under”

• portare “to carry.”

Etymology (PE): Pâdir “a column supporting a building; a post supporting a wall.”

1. To assume (something), as for the sake of argument or as part of a proposition or theory.
   

2. To consider (something) as a possibility suggested or an idea or plan proposed (Dictionary.com).

Etymology (EN): M.E. supposen, from O.Fr. supposer, from L. supponere “to put or place under,” from → sub- “under” + ponere “to put, place,”
→ position.

Etymology (PE): Engâštan, engâridan “to suppose,” from Mid.Pers. (h)angârtan “to conside, to bear in mind, to regard as,” from han, ham “together” → com- + kartan “to establish; to declare; to found;” Av. han-kârayeiti, from han-, ham- “together,” + kar- “to remember; to impress on memory.”

1. To put down by authority or force.
   

2. To keep from public knowledge.
   

3. To restrain from a usual course or action. → suppression.

Etymology (EN): L. suppressus, p.p. of supprimere “to press down, stop, stifle,” from → sub- “down, under” + premere “to press, push against,” → express.

Etymology (PE): Nehâvidan, from ne-, → ni- “down, below,” + hâvidan “to press,” → express.

The act of suppressing; the state of being suppressed. → Compton suppression, → zero suppression.

See also: → suppress; → -tion.

A prefix denoting “over, above, beyond, greater than.”

Etymology (EN): From L. supra “above, over, before, beyond,” → super-.

Etymology (PE): Farâz “above, up, upon,” → height; bâlâ “above, up, high,” → height; abar-, → super-.

In some stellar models, particularly for evolved → massive stars,
such as → red supergiants, → Luminous Blue Variables, and → Wolf-Rayet stars,
an outermost layer of the stellar envelope where the luminosity might exceed the → Eddington limit.
This is due to the → opacity peak produced by the variation in the ionization level of hydrogen in the outer → convective envelope, beneath the surface, of very luminous stars. The opacity peak generates supra-Eddington layers and density inversion. The high opacity decreases the Eddington luminosity in these layers, possibly to fainter levels than the actual stellar luminosity. As a result, the → radiative acceleration exceeds the
→ gravitational acceleration leading to → mass loss enhancement
(see, e.g., A. Maeder, Physics, Formation and Evolution of Rotating Stars, Springer, 2009).

See also: → supra-; → Eddington limit; → layer.

A member of a rare class of objects found in → globular clusters to lie about one magnitude above and to the blue part of the → horizontal branch. These stars are identified as post → EHB stars on their way from to the → asymptotic giant branch.

See also: → supra-; → horizontal; → branch; → star.

An → atmospheric escape mechanism that occurs where individual atoms or molecules in the atmosphere are raised to → escape velocity because of chemical reactions or ionic interactions. Same as
→ nonthermal escape (see, e.g., Catling, D. C. and Kasting, J. F., 2017, Escape of Atmospheres to Space, pp. 129-167. Cambridge University Press).

See also: → supra-; → thermal; → escape.

1. Highest in rank or authority.
   

   2. Of the highest quality, degree, character, importance, etc.

Etymology (EN): M.E., from M.Fr. suprême, and directly from L. supremus “highest,” superlative of superus “situated above,” from super “above,” → super-.

Etymology (PE): Abartom “highest,” from abar “high, upon,” → super-, + -tom superlative suffix, → extreme.

A prefix meaning “over, above, beyond, in addition,” occurring mainly in loanwords from Fr.

Etymology (EN): From O.Fr. sour-, sor-, sur-, from L. → super-.

Etymology (PE): Bar-, abar-, → super-; ru-, ruy- “face, surface; aspect; appearance,” variant rox (Mid.Pers. rôy, rôdh “face;” Av. raoδa- “growth,” in plural form “appearance,” from raod- “to grow, sprout, shoot;” cf. Skt. róha- “rising, height”).

Free from doubt as to the reliability, character, action, etc., of something (Dictionary.com).

Etymology (EN): M.E. sur(e), from M.Fr. sur, O.Fr. seur “safe, secure; trustworthy,” from L. securus “free from care, untroubled, safe,” from *se cura, from se “free from” + cura “care.”

Etymology (PE): Tenz, from (Fine-e Bandar Abbâs) tenz “firm, fixed, solid,” variant tereng; (Tabari) tereng, təreq “firm, fixed;” (Baxtiyâri) teng “firm;” cf. Baluci tranj-, dranjit, tranjit/drannj-, draht, dratk “to hang up;” ultimately from Proto-Ir. *dra(n)j- “to fix, fasten, hold;”
Av. drənj- (draž-) “to fix, fasten, hold;” Parthian (*abi-) ‘bdrynj- “to be sure, secure; make certain;” Khotanese drys- “to hold;” cognate with Gk. drassomai “I hold (with the hand), take;” O.Irish dringid “he climbs;” M.Welsh dringo “to climb;” PIE *dreg^h- “to hold, fasten.”

Without doub; certainly; to be sure; for sure.

See also: → sure; → -ly.

1. Security against loss or damage or for the fulfillment of an obligation, the payment of a debt, etc.; a pledge, guaranty, or bond.
   

2. The state or quality of being sure (Dictionary.com).

Etymology (EN): M.E. surte, from M.Fr., from O.Fr. seurte “a promise, pledge, guarantee; assurance, confidence;” from L. securitas “freedom from care or danger, safety,” from securus, → secure.

1. The outer face, outside, or exterior boundary of a thing; outermost or uppermost layer or area.
   

2. Math.: An infinite aggregate of points constituting space of two dimensions; part or all of the boundary of a solid.

See also: → sur-; → face.

The brightness of an extended object, such as a planet, nebula, galaxy, or the sky background, expressed as magnitudes per unit area (usually square arc second). Surface brightness is calculated by dividing the object’s magnitude by its size (→ isophotal radius).

See also: → surface; → brightness.

A current whose core of maximum velocity is near the surface.

See also: → surface; → current.

The amount of a quantity distributed over a surface area divided by the area, such as a surface-charge density.

See also: → surface; → density.

1. The rate at which a small object in free fall near the surface of a body is accelerated by the gravitational force of the body: g = GM / R², where G is the gravitational constant, and M and R are the mass and radius of the object. The
   surface gravity of Earth is equal to 980 cm s^-2.
   

2. → black hole surface gravity.

See also: → surface; → gravity.

Same as → last scattering surface.

See also: → surface; → last; → scattering.

1. For a star, same as → effective temperature.
   

2. Meteo.: The air temperature at or near the earth’s surface.

See also: → surface; → temperature.

The inward → attraction of the → molecules at the → surface of a → liquid. The reason is that the molecules at the surface do not have other like molecules on all sides of them and consequently they cohere more strongly to those directly associated with them on the surface. Also called surface energy and capillary forces.

See also: → surface; → tension.

Electricity: A sudden rush or burst of current or voltage.
Sun: A jet of material from an active region that reaches coronal heights
and then either fades or returns into the chromosphere along the trajectory of ascent.

Etymology (EN): From M.Fr. sourgir “to rise, swell,” from L. surgere “to rise, spring out” from → sub- “up from below” + regere “to keep straight, guide,” cognate with Pers. râst, → right.

Etymology (PE): Boruntâz, from borun “out, the outside,” → out, + tâz present stem of tâxtan, tâzidan “to run; to hasten; to assault”
(Mid.Pers. tak “assault, attack;” Av. taka- “leap, run,” from tak- “to run, flow;” cf. Skt. tak- “to rush, to hurry,” takti “runs;” O.Ir. tech- “to flow;” Lith. teketi “to walk, to flow;” O.C.S. tešti “to walk, to hurry;” Tokharian B cake “river;” PIE base *tek^w- “to run; to flow”).

A mapping f of a set A onto a set B in such a way that every b element of B is the image of at least one element a of A. In other words, for any element b of B, the equation f(a) = b yields at least one solution.
Allso called → surjective mapping.

See also: From → sur- + → injection.

Of or pertaining to a → surjection.

See also: → sur-; → injection.

Same as → surjection.

See also: → surjective; → mapping.

1. A → conjecture or → guess.
   

   2. To conjecture or guess.

Etymology (EN): M.E. surmisen, from O.Fr. surmis “accusation,” noun use of p.p. of surmettre
“to accuse,” from → sur- + mettre “put,” from L. mittere, → mission.

Etymology (PE): Râxé, from râx (Dehxodâ) “conjecture, opinion; sorrow, sadness.”

1. General: A general or comprehensive view; a detailed inspection or investigation.
   

2. Astro.: The observation and recording of large extents of the sky with a particular instrument using one or more wavelengths in the same spectral domain. → all-sky survey; → infrared survey; → redshift survey; → photographic survey.
   

3. To conduct a survey of.

Etymology (EN): M.E. surveien, from M.Fr. surv(e)eir, surveoir “to oversee,”
from L. supervidere, from → super-

• videre “to look;” cognate with Pers. bin present stem of didan “to see;” Mid.Pers. wyn-; O.Pers. vain- “to see;” Av. vaēn- “to see;”
  cf. Skt. veda “I know;” Gk. oida “I know,” idein “to see;” L. videre “to see;” PIE base *weid- “to know, to see.”

Etymology (PE): Bardid from bar- “up; upon; on; in; into; at; forth; with; near; before; according to” (Mid.Pers. abar; O.Pers. upariy “above; over, upon, according to;” Av. upairi “above, over,” upairi.zəma- “located above the earth;” cf. Gk. hyper- “over, above;” L. super-; O.H.G. ubir “over;” PIE base *uper “over”)

• did past stem of didan “to see” (Mid.Pers. ditan “to see, regard, catch sight of, contemplate, experience;” O.Pers. dī- “to see;” Av. dā(y)- “to see,” didāti “sees;” cf.
  Skt. dhī- “to perceive, think, ponder; thought, reflection, meditation,” dādhye; Gk. dedorka “have seen”).

1. A person whose occupation is taking accurate measurements of land areas in order to determine boundaries, elevations, and dimensions.
   
2. One of a series of space probes (1966-1968) that analyzed lunar soil and obtained other scientific information after soft-landing on the Moon.

See also: → survey; → -or.

The act or fact of surviving, especially under adverse or unusual circumstances (Dictionary.com).

See also: → survive; → -al.

To remain alive after the death of someone, the cessation of something, or the occurrence of some event; continue to live (Dictionary.com).

Etymology (EN): M.E., from O.Fr. souvivre, from L. supervivere “live beyond, live longer than,” from → super- “over, beyond,” + vivere “to live,” cognate with Gk. bios, → bio-, and Pers. zistan “to live,” as below.

Etymology (PE): Barzividan, from bar- “over, above,” variant of abar-, → super-, + zividan, from Mid.Pers. zivastan “to live,” zivik, zivandag “alive, living,” Mod.Pers. zistan “to live;” cf. O.Pers./Av. gay- “to live;” Av. gaya- “life,” gaeθâ- “being, world, mankind,” jivya-, jva- “aliving, alive,” Skt. jivah “alive, living;” Gk. bios “life;” L. vivus “living, alive,” vita “life;” O.E. cwic “alive;” E. quick, Lith. gyvas “living, alive;” PIE base *gweie- “to live.”

State or character of being susceptible. → magnetic susceptibility

Etymology (EN): M.L. susceptibilitas, from susceptibilis “capable, sustainable, susceptible,” from susceptus, p.p. of suscipere “sustain, support, acknowledge,” from sub “up from under” + capere “to take” ……

Etymology (PE): Barxodgiri, from bar- “up; upon; on; in; into; at; forth; with; near; before; according to” (Mid.Pers. abar; O.Pers. upariy “above; over, upon, according to;” Av. upairi “above, over,” upairi.zəma- “located above the earth;” cf. Gk. hyper- “over, above;” L. super-; O.H.G. ubir “over;” PIE base *uper “over”) + xod “self, own” (Mid.Pers. xwad “self; indeed;”
Av. hva- “self, own”) + giri vebal noun of gereftan “to take, seize, hold” (Mid.Pers. griftan, gir- “to take, hold, restrain;” O.Pers./Av. grab- “to take, seize,”
cf. Skt. grah-, grabh- “to seize, take,” graha- “seizing, holding, perceiving,” M.L.G. grabben “to grab,” from P.Gmc. *grab, E. grab “to take or grasp suddenly;” PIE *ghrebh- “to seize”).

1. To believe to be guilty, false, counterfeit, undesirable, defective, bad, etc., with little or no proof.
   

2. A person who is suspected, especially one suspected of a crime, offense, or the like (Dictionary.com).

Etymology (EN): M.E., from M.Fr. suspecter, from O.Fr. suspect, from L. suspectus “suspected, regarded with suspicion or mistrust,” p.p. of suspicere “look up at, look upward,” from assimilated form of → sub-

• specere, “to look at,” → -scope.

Etymology (PE): Bargâsidan, from bar- “on; up; upon; in; into; at; forth; with,” → on-, + gâsidan “to look at,” → speculate; bargâsâr, from bargâs + -âr, contraction of âvar agent noun of âvardan “to bring; to cause, produce,” → format.

Believed likely.

See also: Past participle of → suspect.

1. The state of mind or feeling of one who suspects.
   

2. An instance of suspecting something or someone (Dictionary.com).

Etymology (EN): M.E., from suspecioun, from O.Fr. suspicion, sospeçon “mistrust, suspicion,” from L.L. suspectionem “mistrust, suspicion, fear,” noun of state from past participle stem of L. suspicere “to look up at,” → suspect.

Etymology (PE): Verbal noun from bargâsidan, → suspect.

1. Tending to cause or excite suspicion; questionable.
   

2. Inclined to suspect, especially inclined to suspect evil; distrustful.
   

3. Full of or feeling suspicion (Dictionary.com).

Etymology (EN): M.E., from O.Fr. sospecious, from L. suspiciosus, suspitiosus “exciting suspicion, causing mistrust,” from stem of suspicere, → suspect.

Etymology (PE): Bargâsnâk, from bargâs present stem of pargâsidan, → suspect, + -nâk adj. suffix.

To cause or allow something to continue for a long period of time.

Etymology (EN): M.E. suste(i)nen, from O.Fr. sustenir “hold up, endure,” from L. sustinere “hold up, support, endure,” from → sub- “up from below” + tenere “to hold,” from from PIE root *ten- “to stretch,” → tension.

Etymology (PE): Padârdan, from Sogd. padâr “to sustain, support,” from Proto-Ir. *pati-dar-, from *pati- “to, toward, in, at, agianst,” → ad hoc, + *dar “to hold, keep, maintain,” → property, + -dan infinitive suffix.

An ecological concept, the property or condition of being → sustainable.

See also: Quality, state noun from → sustainable.

Ecology: Maintaining ecological balance; exploiting natural resources without destroying the ecological balance of an area, e.g. → sustainable agriculture;
→ sustainable development.

See also: → sustain; → -able.

The ability of a farm to produce food indefinitely, without causing severe or irreversible damage to → ecosystem health.

See also: → sustainable; → agriculture.

Ecology: A development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

See also: → sustainable; → development.