Fr.: synthèse d'ouverture
The method of combining the signals received by several smaller telescopes distributed over a very large area or baseline to provide the high angular resolution of a much large telescope.
Big Bang nucleosynthesis (BBN)
haste-handâyeš-e Meh Bâng, ~ Big Bang
Fr.: nucléosynthèse de Big Bang
The production of → light elements, roughly three minutes after the → Big Bang when the temperature of the → Universe dropped from 1032 K to approximately 109 K. In a short time interval → protons and → neutrons collided to produce → deuterium. Most of the deuterium then fused with other protons and neutrons to produce → helium and a small amount of → tritium. The element → lithium 7 could also arise form the coalescence of one tritium and two deuterium nuclei. According to the Big Bang nucleosynthesis theory, roughly 25% of the mass of the Universe consists of helium. It also predicts about 0.01% deuterium, and even smaller quantities of lithium. These predictions depend critically on the → baryon-photon ratio. Same as → primordial nucleosynthesis.
→ Big Bang; → nucleosynthesis.
In biochemistry, the ability to produce organic compounds using energy contained in inorganic molecules. Chemosynthesis is similar to → photosynthesis. Instead of using light as an energy source to make food, energy or compounds from chemical reactions is used. Most chemosynthetic organisms are bacteria.
hasté andâyeš-e oskafti
Fr.: nucléosynthèse explosive
The explosive processes that are believed to occur in supernovae. Explosive carbon burning occurs at a temperature of about 2 × 109 degrees and produces the nuclei from neon to silicon. Explosive oxygen burning occurs near 4 × 109 degrees and produces nuclei between silicon and calcium in atomic weight.At higher temperatures, still heavier nuclei are produced.
→ explosive; → nucleosynthesis.
The process by which → nuclear reactions at very high temperatures and pressures produce the various → chemical elements of the → periodic table, either in the → Big Bang or in stellar interiors. See also → primordial nucleosynthesis, → stellar nucleosynthesis, → explosive nucleosynthesis.
From nucleo-, combining form of → nucleus + → synthesis.
The process in green plants, algae, diatoms, and certain forms of bacteria by which carbohydrates are synthesized from carbon dioxide and water using light as an energy source. Most forms of photosynthesis release oxygen as a byproduct.
Fr.: nucléosynthèse primordiale
The formation of → chemical elements in the → early Universe, between about 0.01 seconds and 3 minutes after the → Big Bang, when the nuclei of primordial matter collided and fused with one another. Most of the → helium in the → Universe was created by this process. Same as → Big Bang nucleosynthesis
→ primordial; → nucleosynthesis.
Fr.: synthèse spectrale
The process of computing line strengths in stellar spectra using an appropriate stellar atmosphere model, atomic and molecular data, and the numerical solution of the → radiative transfer equation at each point in the spectrum.
Fr.: nucléosynthèse stellaire
The → nuclear reaction process taking place inside stars, whereby → chemical elements are produced from pre-existing nuclei heavier than → hydrogen and → helium.
→ stellar; → nucleosynthesis.
stellar population synthesis
handâyeš-e porinešhâ-ye setâre-yi
Fr.: synthèse de poupulations stellaires
A theoretical model that reconstructs the integrated spectrum of → stellar populations from an empirical library of stellar spectra containing the range of types expected to be present in the sample. The light received from a given galaxy is emitted by a large number of stars that may have different masses, ages, and metallicities. Stellar population synthesis models are tools for interpreting the integrated light that we observe from the galaxies.
→ stellar; → population; → model.
The combining of the constituent elements of separate materials or
abstract entities into a single or unified entity; opposite of
→ aperture synthesis;
From L. synthesis "collection, set," from Gk. synthesis "composition," from syntithenai "put together, combine," from → syn- "together" + tithenai "to put, place," from PIE base *dhe- "to put, to do," cf. Pers. dâdan "to give," as below.
Handâyeš, from han-, variant ham- "together," → syn- + O.Pers./Av. dā- "to give, grant, put," dadāiti "he gives;" Mid.Pers./Mod.Pers. dâdan "to give, put" (cf. Skt. dadáti "he gives;" Gk. tithenai "to place, put, set," didomi "I give;" L. dare "to give, offer;" Rus. delat' "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do;" PIE base *dhe- "to put, to do") + -y- epenthetic vowel + -eš verbal noun suffix, → synthesize.