An Etymological Dictionary of Astronomy and Astrophysics
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A → profile representing the number density of stars in the → core of a galaxy.

→ core; → profile.

1) A → profile representing the → density of a quantity.
2) A → profile representing the distribution of stars as a function of their number in a region.

→ density; → profile.

The shape of the spectral line resulting from the Doppler broadening.

→ Doppler effect; → profile.

The shape of a curve representing a normal distribution.

→ Gaussian; → profile.

The shape of instrument's response to the input signal. The Fourier transform of the source function by the instrument function.

→ instrumental; → profile.

A line profile in which the emission is on the blue side of the absorption. It is usually interpreted as the redshift of the absorption component relative to emission lines, which necessitates infall of matter.

→ inverse; → P Cygni; → line; → profile.

The representation of a spectral line as produced by an observing instrument.

→ line, → profile.

The change in the shape of a → spectral line over time. For instance, in → Wolf-Rayet stars the line profile varying on time-scales of minutes to hours is attributed to → microturbulence.

→ line; → profile; → variability.

A spectral profile in which the intensity distribution follows a specific mathematical function (Lorentz or Cauchy probability). Compared to the normal or Gaussian profile, Lorentzian has a pointed peak and more important wings.

→ Lorentz; → profile.

The shape of a pulsar's pulse as determined by averaging several pulses.

→ mean; → profile.

A feature in a stellar spectrum showing strong hydrogen and helium emission lines with absorption lines on their blueward wing. This line profile indicates a strong outflow of matter from a star. → inverse P Cygni line profile.

After → P Cygni star.

A graph or drawing that shows the variation of one property (such as intensity), usually as ordinate, with respect to another property (such as wavelength). → line profile.

From It. profilo "a drawing in outline," from profilare "to draw in outline," from → pro- "forth" + filare "draw out, spin," from L.L. filare "to spin, draw out a line," from filum "thread," cognate with Pers. zeh "cord, string," → filament.

Farâpâl, from farâ-, → pro-, + pâl "thread, string," probably cognate with L. filum, as above.

A method of analysis in which the observed stellar image profiles or spectral line profiles are fitted by model profiles in order to study and derive some properties of the object.

→ profile; → fitting; → method.

A mathematical function that describes how the → intensity  I of a → galaxy varies with distance R from its center. It is given by: (dln I/dln R) = -(b/n)(R/R_e)^1/n. The constant b is chosen such that R_e is the → effective radius; n is the Sérsic index. The Sérsic profile is a generalization of → de Vaucouleurs law. Setting n = 4 gives the de Vaucouleurs profile.

J. L. Sérsic, 1963, Boletin de la Asociacion Argentina de Astronomia, Vol. 6, p.41; → profile.

A plot of the fluid velocity as a function of position.

→ velocity; → profile.

A spectral profile in which a → spectral line is broadened by two types of mechanisms, one of which alone would produce a & rarr; Gaussian profile (usually, as a result of the → Doppler broadening), and the other would produce a → Lorentzian profile.

After Woldemar Voigt (1850-1919), a German physicist; → profile.