An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 23 Search : problem
two-body problem
  پراسه‌ی ِ دو جسم   
parâse-ye do jesm

Fr.: problème à deux corps   

In classical mechanics, the study concerned with the dynamics of an isolated system of two particles subject only to the Newtonian gravitational force between them. The problem can be separated into two single-particle problems with the following solutions. The equation of the → center of mass is governed by the equation of the same form as that for a single particle. Moreover, the motion of either particle, with respect to the other as origin, is the same as the motion with respect to a fixed origin of a single particle of → reduced mass acted on by the same internal force. See also → three-body problem, → n-body problem.

two; → body; → problem.

weak wind problem
  پراسه‌ی ِ باد ِ نزار، ~ ~ کمزور   
parâse-ye bâd-e nezâr, ~ ~ kamzur

Fr.: problème de faible vent   

The discrepancy between the observed → mass loss rates and the predicted values for → weak-wind O-type stars.

weak; → wind; → problem.

winding problem
  پراسه‌ی ِ پیچش   
parâse-ye piceš

Fr.: problème d'enroulement   

The problem encountered in the explanation of the → spiral arms of galaxies if the material making up a spiral arm is static, that is remains in the arm. Since galaxies exhibit → differential rotation, stars near the center take less time to orbit the center than those farther from the center. The arm would, after a few → galactic rotations, become increasingly curved and wind around the → galaxy ever tighter until it ultimately disappears. This is inconsistent with observations.

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