An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



Number of Results: 15 Search : combination
affine combination
  میازش ِ کروَن   
miyâzeš-e karvan

Fr.: combinaison affine   

A linear combination of vectors in which all the vector coefficients add up to one.

affine; → combination.


Fr.: combinaison   

1) General: The act of combining or the state of being combined.
2) Math: The number of ways elements making up a set can be arranged into various groups without regard to their order in the group. → permutation

Noun from → combine

dissociative recombination
  بازمیازش ِ واهزشی   
bâzmiyâzeš-e vâhazeši

Fr.: recombinaison dissociative   

A process where a positive molecular ion recombines with an electron, and as a result it dissociates into two neutral products. For example, AB+ + e-→ A + B, where e- is an electron, AB+ is a diatomic or polyatomic molecular ion, and A and B are the neutral fragmentation products. Dissociative recombination is the dominant recombination process in planetary ionospheres and interstellar clouds.

dissociative; → recombination.

radiative recombination
  بازمیازش ِ تابشی   
bâzmiyâzeš-e tâbeši

Fr.: recombinaison radiative   

The process by which an ionized atom binds a free electron in a → plasma to produce a new atomic state with the subsequent radiation of photons.

radiative; → recombination.

radio recombination line
  خط ِ بازمیازش ِ رادیویی   
xatt-e bâzmiyâzeš-e râdioyi

Fr.: raie de recombinaison radio   

A → recombination line whose wavelength lies in the radio range of the electromagnetic spectrum. Radio recombination lines are the result of electronic transitions between high energy levels (n > 50) in an atom or ion.

radio; → recombination line.


Fr.: recombinaison   

1) The process or result of combining again.
2) The capture of an electron by a positive ion. It is the inverse process to → ionization.

Verbal noun of → recombine.

recombination coefficient
  همگر ِ بازمیازش   
hamgar-e bâzmiyâzeš

Fr.: coefficient de recombinaison   

A measure of the specific rate at which oppositely charged ions join to form neutral particles. It is given by the rate at which those ions recombine, divided by the product of the densities of the two species involved.

recombination; → coefficient.

recombination continuum
  پیوستار ِ بازمیازش   
peyvastâr-e bâzmiyâzeš

Fr.: continuum de recombinaison   

A recombination radiation that is continuous over a range of frequencies. Same as → continuum emission.

recombination; → continuum.

recombination epoch
  زیمه‌ی ِ بازمیازش   
zime-ye bâzmiyâzeš

Fr.: époque de recombinaison   

Same as → recombination era.

recombination; → epoch.

recombination era
  دوران ِ بازمیازش   
dowrân-e bâzmiyâzeš

Fr.: ère de recombinaison   

The era some 380,000 years after the → Big Bang (at a → redshift of about 1,100), when the Universe had cooled sufficiently so that protons and electrons combined to form → neutral hydrogen in a process called → recombination. The temperature was about 3,000 K and the ionization fraction low enough for Universe to become transparent to light. Consequently matter and radiation decouple from one another because no further → scattering of the radiation occurs. The observation of the → cosmic microwave background radiation provides a means of studying the Universe at the recombination era. Also called recombination epoch and → decoupling era.

recombination; → era.

recombination line
  خط ِ بازمیازش   
xatt-e bâzmiyâzeš

Fr.: raie de recombinaison   

An → emission line in a spectrum produced in an → H II region when a free electron combines with an ionized atom to form a neutral atom or an ion of lower → ionization stage. Same as → free-bound emission.

recombination; → line.

recombination radiation
  تابش ِ بازمیازش   
tâbeš-e bâzmiyâzeš

Fr.: rayonnement de recombinaison   

Radiation produced when a free electron in a plasma is captured by an ionized atom.

recombination; → radiation.

recombination rate
  نرخ ِ بازمیازش   
nerx-e bâzmiyâzeš

Fr.: taux de recombinaison   

In → H II regions the rate at which free electrons recombine with → ionized hydrogen atoms (protons).

recombination; → rate.

recombination time
  زمان ِ بازمیازش   
zamân-e bâzmiyâzeš

Fr.: temps de recombinaison   

The time period necessary for a cloud of atomic hydrogen to be → ionized by the ultraviolet photons of a central → massive stars.

recombination; → time.

Ritz combination principle
  پروز ِ میازش ِ ریتز   
parvaz-e miyâzeš-e Ritz

Fr.: principe de combinaison de Ritz   

An empirical rule discovered before the advent of quantum mechanics which states that it is possible to find pairs of spectral lines, which have the property that the sum of their wavenumbers is also an observed spectral line.

Named after Walther Ritz (1878-1909), a Swiss theoretical physicist; → combination; → principle.