# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 59 Search : press
 pressure mode   ترز ِ فشار، مد ِ ~   tarz-e fešÃ¢r, mod-e ~Fr.: mode pression   Same as → p mode→ pressure; → mode. pressure scale height   بلندی ِ مرپل ِ فشار   bolandi-ye marpel-e fešârFr.: hauteur d'échelle de pression   A basic ingredient of the → mixing length theory that scales with the → mixing length. It is defined by the relation: HP = -dr/dln P = -Pdr/dP , where r is the height and P the pressure. See also → scale height.→ pressure; → scale; → height. radiation pressure   فشار ِ تابش   fešâr-e tâbešFr.: pression de radiation   The → momentum carried by → photons to a surface exposed to → electromagnetic radiation. Stellar radiation pressure on big and massive objects is insignificant, but it has considerable effects on → gas and → dust particles. Radiation pressure is particularly important for → massive stars. See, for example, → Eddington limit, → radiation-driven wind , and → radiation-driven implosion. The → solar radiation pressure is also at the origin of various physical phenomena, e.g. → gas tails in → comets and → Poynting-Robertson effect.→ radiation; → pressure. ram pressure   فشار ِ قوچ‌وار   fešâr-e qucvârFr.: pression dynamique   The pressure exerted on a body moving through a → fluid medium. For example, a → meteor traveling through the Earth's atmosphere produces a → shock wave generated by the extremely rapid → compression of air in front of the → meteoroid. It is primarily this ram pressure (rather than → friction) that heats the air which in turn heats the meteoroid as it flows around the meteoroid. The ram pressure increases with → velocity according to the relation P = (1/2)ρv2, where ρ is the density of the medium and v the relative velocity between the body and the medium. Similarly, → ram pressure stripping produces → jellyfish galaxies. Same as → dynamic pressure.→ ram; → pressure. ram pressure stripping   لُختانش با فشار ِ قوچوار   loxtâneš bâ fešâr-e qucvârFr.: balayage par la pression dynamique   A process proposed to explain the observed absence of gas-rich galaxies in → galaxy clusters whereby a galaxy loses its gas when it falls into a cluster. There is a tremendous amount of hot (~ 107 K) and tenuous (~ 10-4 cm-3) gas (several 1013 → solar masses) in the → intracluster medium (ICM). Ram pressure stripping was first proposed by Gunn & Gott (1972) who noted that galaxies falling into clusters feel an ICM wind. If this wind can overcome the → gravitational attraction between the stellar and gas disks, then the gas disk will be blown away. The mapping of the gas content of spiral galaxies in the → Virgo cluster showed that the → neutral hydrogen (H I) disks of cluster spiral galaxies are disturbed and considerably reduced. Their molecular gas, more bound to the galaxy, is less perturbed, but still may be swept out in case of very strong ram pressure. These observational results indicate that the gas removal due to the rapid motion of the galaxy within the intracluster medium is responsible for the H I deficiency and the disturbed gas disks of the cluster spirals (e.g., J. A. Hester, 2006, ApJ 647:910).→ ram; → pressure; → strip. solar depression   نشیب ِ خورشید   nešib-e xoršidFr.: dépression solaire   The → angle between the → sea horizon, the → center of → Earth, and the center of the → solar disk.→ solar; → depression. solar radiation pressure   فشار ِ تابش ِ خورشید   fešâr-e tâbeš xoršid (#)Fr.: pression du rayonnement solaire   The → radiation pressure of solar photons, which pushes a comet's dust outward to form a → dust tail.→ solar; → radiation; → pressure. sound pressure   فشار ِ صدا   fešâr-e sedâFr.: 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. stagnation pressure   فشار ِ ناروانی   fešâr-e nâravâniFr.: pression de stagnation   The sum of → static pressure and → dynamic pressure in the → Bernoulli equation.→ stagnation; → pressure. standard temperature and pressure (STP)   دما و فشار ِ استانده   damâ o fešâr-e estândéFr.: conditions normales de température et de pression   1) The most commonly used definition is temperature of 273.15 K (0 °C) and pressure of 1 → atmosphere. 2) Chemistry: Temperature of 273.15 K (0 °C) and pressure of 105  → pascal (Pa)s (1 → bar). International Union of Pure and Applied Chemistry (IUPAC) recommends that the former use of the pressure of 1 atm as standard pressure (equivalent to 1.01325 × 105 Pa) should be discontinued.→ standard; → temperature; → pressure. static pressure   فشار ِ ایستا   fešâr-e istâFr.: pression statique   In → fluid mechanics, the → pressure felt by an object suspended in a → fluid and moving with it. This pressure is called static because the object is not moving relative to the fluid. See also → dynamic pressure.→ static; → pressure. suppress   نهاویدن   nehâvidanFr.: supprimer   1) To put down by authority or force. 2) To keep from public knowledge. 3) To restrain from a usual course or action. → suppression.L. suppressus, p.p. of supprimere "to press down, stop, stifle," from → sub- "down, under" + premere "to press, push against," → express.Nehâvidan, from ne-, → ni- "down, below," + hâvidan "to press," → express. suppression   نهاوش   nehâvešFr.: suppression   The act of suppressing; the state of being suppressed. → Compton suppression, → zero suppression.→ suppress; → -tion. thermal pressure   فشار ِ گرمایی   fešâr-e garmâyi (#)Fr.: pression thermale   The ordinary pressure in a gas that is due to motions of particles and can be attributed to the object's → temperature.→ thermal; → pressure. total pressure   فشار ِ هماک   fešâr-e hamâkFr.: pression totale   The sum of → static pressure, → dynamic pressure, and → hydrostatic pressure in the → Bernoulli equation.→ total, → pressure. vapor pressure   فشار ِ بخار   fešâr-e boxârFr.: pression de vapeur   The equilibrium pressure of a vapor above its condensed phases (liquid or solid). In other words, the pressure of the vapor resulting from evaporation of a liquid (or solid) above a sample of the liquid (or solid) in a closed container. The vapor pressure varies with the temperature. As the temperature increases its the vapor pressure also increases, and conversely. The temperature at which the vapor pressure is equal to the atmospheric pressure is called the → boiling point. For example, at 20 °C, water would boil at a pressure of about 0.023 atm, or about a fortieth of atmospheric pressure.→ vapor; → pressure. velocity pressure   فشار ِ توانیک   fešâr-e tavânikFr.: pression dynamique   → velocity; → pressure. Wilson depression   نشیب ِ ویلسون   našib-e WilsonFr.: dépression de Wilson   The depression on the → Sun's → photosphere associated with → sunspots and involving the → Wilson effect. The measured depression values vary between about 700 and 2,000 km. zero suppression   نهاوش ِ صفر   nehâveš-e sefrFr.: suppression de zéro   The removal of non-significant zeroes from a number. For example, replacing 531.2300 by 531.23.→ zero; → suppression.

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