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

In a self-regulatory system, monitoring a disturbance before it enters the → system to apply corrections before the disturbance has influenced the system. See also → feedback.

→ feed; → forward.

1a) To or toward what is ahead or in front.
1b) Directed toward a point in advance.
2) To send forward; transmit, especially (a letter or email) to a different address.

From fore "before, in front of," cognate with Pers. farâ, → pro-,+ → -ward.

Piš-su, from piš "forward; in front of; before;" Mid.Pers. pêš, + su, → direction.

Scattering in which photons emerge from the → scattering medium travelling predominantly in the same direction as they entered. The → halos around the Sun and Moon in wet weather are caused by forward scattering by water droplets in the Earth's atmosphere. → backscattering.

→ forward; → scattering.

1) Geology: The process whereby a geologic section (subsurface model of one-, two-, or three dimensions) is transformed into a synthetic seismogram (synthetic seismic record).
2) In → asteroseismology, a model that takes the physical properties of a star as input parameters and predicts the star's oscillations. Then, by finding parameters that yield oscillation frequencies (ω_nlm) close to those observed, one can infer the properties of the observed star. The quantum numbers n, l, and m must be identified before any meaningful comparison between seismic data and model predictions can be made. That mode identification requires a physical interpretation of the measured frequencies.

→ forward; → seismic; → modeling.

A highly → supersonic → shock wave created in a → supernova remnant as the expanding stellar ejecta runs into the → interstellar medium (ISM). This forward shock wave produces sudden, large changes in pressure and temperature behind the shock wave. The forward shock wave also accelerates electrons and other charged particles to extremely high energies. The forward shock front has a velocity of 10⁴ km s^-1 and can heat the shocked gas to temperatures ~ 10⁹ K. While the forward shock continues to expand into the ISM, it creates a → reverse shock that travels back into the freely expanding → supernova ejecta.

→ forward; → shock.