An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1298
sonic point
  نقطه‌ی ِ صدایی   
noqte-ye sedâyi

Fr.: point sonique   

The point where the → stellar wind makes a transition from → subsonic to → supersonic flow. In the particular case of a spherically symmetric wind (thus with no magnetic field), the distance from star, at which the sonic point occurs, is given by: rs = (GM*)/2cs2, where G is the → gravitational constant, M* is the stellar mass, and cs the → sound speed at the sonic point.

sonic; → point.



To gather on a surface either by absorption, adsorption, or a combination of the two processes.

Verb, from sorption, extracted from → absorptionadsorption, from L. sorbere "suck in," from PIE base *srebh- "to suck, absorb" (cf. Arm. arbi "I drank;" Gk. rhopheo "to gulp down;" Lith. srebiu "to drink greedily").

Šamidan, from šam, variant of šâm, as in âšâm, âšâmidan "to drink, to sip;" Av. šam- "to drink, sip, swallow;" Skt. cam, camati "to sip, dirink, lick up, absorb."


Fr.: sorption   

The process of sorbing. The state of being sorbed. → absorption; → adsorption.

Verbal noun of → sorb

Sothic period
  دوره‌ی ِ تیشتری   
dowre-ye Tištari

Fr.: période sothique   

The interval after which the heliacal rising of the star Sirius occurs at the same time of the year. It is a period of 1,460 Sothic years.

From Fr. sothique, from Gk. Sothis, an Egyptian name of Sirius; → period.

Tištari, of or pertaining to Tištarserius; dowré, → period.

Sothic year
  سال ِ تیشتری   
sâl-e Tištari

Fr.: année sothique   

The Egyptian year of 365 days and 6 hours, as distinguished from them Egyptian vague year, which contained 365 days.

From Fr. sothique, from Gk. Sothis, an Egyptian name of Sirius; → year.

Tištari, of or pertaining to Tištarserius; sâl, → year.

  ۱) صدا؛ ۲) دروا   
1) sedâ (#); 2) dorvâ

Fr.: 1) son; 2) sain   

1) A physiological sensation received by the ear. It is caused by a vibrating source and transmitted as a longitudinal pressure wave motion through a material medium such as air.
2a) Free from damage, injury, decay, etc.
2b) Describing an → argumentiff its → reasoning is → valid and all its → premises are → true.
2c) Logic: A formal system is sound if all the → inferences that are permitted by the rules of the system are valid inferences, that is, if no invalid arguments are provable within the system. → soundness.

1) M.E. soun; O.Fr. son, from L. sonus "sound," sonare "to sound;" PIE base *suen- "to sound;" cf. Av. xvan- "to sound;" Pers. xvân-, xvândan "to sing, read;" Skt. svana- "sound," svan- "to sound," svanati "it sounds;" O.E. swinn "music, song" (Cheung 2007).
2) M.E. sund, from O.E. gesund "sound, safe, having the organs and faculties complete and in perfect action," cf. O.S. gisund, O.Fris. sund, Du. gezond, O.H.G. gisunt, Ger. gesund "healthy," as in interjection gesundheit.

1) Sedâ "sound," most probably a Pers. term, since it exists also in Indo-Aryan languages: Skt. (late Vedic): sabda "articulate sound, noise," Pali and Prakriti: sadda "sound, noise," Sindhi: sadu, sado "shout, call," Gujrâti sad "call, voice, echo," Marathi: sad "shouting to," Konkani sad "sound," Sinhali: sada "sound." Therefore, sadâ in Ar. "reverberating noise, echo" maybe a loan from Pers., or a coincidence. Note that for the author of the classical Pers. dictionary Borhân-e Qâte' (India, 1652 A.D.), the Ar. term is a loanword from Pers.
2) Dorvâ (Dehxodâ) "whole, right, just;" Qâyeni, Gonâbâdi, Tabasi, Râvari dorvâx "healthy, whole," dorvâxi "health" (related to Pers. dorud "benediction, praise," dorost "whole, healthy, right"); cf. Sogd. žûk (from *druva-) "healthy;" O.Pers. duruwa- "healthy, firm, secure;" Av. druua- "healthy, firm, sound," druuatāt "health, soundness," drvô.cašman- "of sound eyes;" Skt. dhruvá- "fixed, firm;" → integral.

sound barrier
  دیوار ِ صدا، ورغه‌ی ِ ~   
divâr-e sedâ, varqe-ye ~

Fr.: mur du son   

A sharp increase in aerodynamic drag that occurs as the speed of an aircraft approaches the speed of sound. Also called sonic barrier.

sound; → barrier.

sound energy
  کاروژ ِ صدا   
kâruž-e sedâ

Fr.: énergie acoustique   

The energy which → sound waves impart to a medium. Same as acoustic energy.

sound; → energy.

sound field
  میدان ِ صدا   
meydân-e sedâ

Fr.: champ acoustique   

The distribution of → sound energy in a defined space.

sound; → field.

sound horizon
  افق ِ صدا   
ofoq-e sedâ

Fr.: horizon sonore   

The maximum distance a → sound wave could have traveled through the ionized plasma from the → Big Bang until the → recombination era. It is 150 → Mpc, or bout 500 million → light-years. Sound horizon is the equivalent of the concept of → cosmic horizon, where one replaces → electromagnetic wave by → sound wave. The sound horizon is a fixed physical scale at the → last scattering surface. Cosmological models relate the value of sound horizon to the angle it subtends on the sky today. Same as acoustic horizon and sonic horizon. See also → CMB angular power spectrum.

sound; → horizon.

sound intensity
  درتنویی ِ صدا   
dartanuyi-ye sedâ

Fr.: intensité de son   

The average → sound power passing through a unit area perpendicular to the direction that the sound is traveling. It is usually expressed in watts per square meter.

sound; → level.

sound intensity level
  تراز ِ درتنویی ِ صدا   
tarâz-e dartanuyi-ye sedâ

Fr.: niveau de l'intensité de son   

The expression of sound intensity in decibel units. The sound intensity level (LI), in decibels, is computed as: LI = 10 log (I/I0), where I is the measured sound intensity and I0 is the reference intensity (1 x 10 -12 watt per square meter).

sound; → intensity; → level.

sound power
  توان ِ صدا   
tavân-e sedâ

Fr.: puissance de son   

The → sound energy emitted by a source per unit time, usually expressed in → watts. Sound power causes → sound pressure.

sound; → power.

sound power level
  تراز ِ توان ِ صدا   
tarâz-e tavân-e sedâ

Fr.: niveau de la puissance de son   

The sound energy emitted by a sound source per unit time and expressed in → decibels. Sound power, in → watts, is converted to sound power level in decibels (L), by L = 10 log (W/W0), where W0 is the reference power (1 x 10 -12 watt).

sound; → power; → level.

sound pressure
  فشار ِ صدا   
fešâr-e sedâ

Fr.: pression de son   

The periodic fluctuation above and below atmospheric pressure created by an oscillating body which provides the → sound power. Instantaneous sound pressure is the peak value of air pressure.

sound; → pressure.

sound quality
  چونی ِ صدا   
cuni-ye sedâ

Fr.: qualité de son   

The number of → overtones present in a sound and their respective intensity. Like → loudness, it is a subjective quantity and cannot be measured with instruments.

sound; → quality.

sound speed
  تندی ِ صدا   
tondi-ye sedâ

Fr.: vitesse du son   

The velocity of propagation of a → longitudinal wave in a medium under specified conditions. Also known as sonic speed, sonic velocity, acoustic velocity, sound velocity, velocity of sound, speed of sound. The speed of sound is a thermodynamic property that relates to the change in pressure and density of the medium and can be expressed as C = (dP/dρ)1/2, where C is the sound velocity, dP is the change in pressure, and dρ the change in density. It can also be expressed as C = (E/ρ)1/2, where E is the bulk modulus elasticity. This equation is valid for liquids, solids and gases. The sound travels faster through media with higher → elasticity and/or lower density. If a medium is → incompressible the speed of sound is infinite. For → ideal gases, a simple relationship exists between the sound speed and temperature: C = (γR T)1/2, where γ is the → specific heat ratio (CP/CV), and R is the → gas constant. We see that for ideal gases it the speed is independent of pressure. In air at 0°C it is 332 m/sec. The speed of sound in a gas of hydrogen is 1315 m/s. → Mach number.

sound; → speed.

sound wave
  موج ِ صدا   
mowj-e sedâ (#)

Fr.: onde sonore   

A → longitudinal wave which when striking the ear gives rise to the sensation of sound. Such waves can be propagated in solids, liquids, and gases. The material particles transmitting sound waves oscillate in the direction of propagation of the wave itself. There is a large range of frequencies within which longitudinal waves can stimulate the human ear and brain to the sensation of hearing. This range is from about 20 → Hz to about 20,000 Hz and is called the audible range. → ultrasound; → infrasound.

sound; → wave.


Fr.: sondage, radiosondage   

1) In geophysics, any penetration of the natural environment for scientific observation.
2) In meteorology, a free, unmanned balloon carrying instruments aloft to make atmospheric measurements, esp. a radiosonde balloon.
3) The measurement of the depth of water beneath a vessel.

From Fr. sonder, → sonde.

From gomâné, → sonde, + zani verbal noun of zadan "to do; to strike, beat; to play an instrument" (Mid.Pers. zatan, žatan; O.Pers./Av. jan-, gan- "to strike, hit, smite, kill" (jantar- "smiter"); cf. Skt. han- "to strike, beat" (hantar- "smiter, killer"); Gk. theinein "to strike;" L. fendere "to strike, push;" Gmc. *gundjo "war, battle;" PIE *gwhen- "to strike, kill").

sounding balloon
  بالون ِ گمانه‌زنی   
bâlon-e gamâne-zani

Fr.: ballon-sonde   

A small, free balloon sent into the upper atmosphere to measure, record, and transmit meteorological reports to a ground station.

sounding; → balloon.

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