Fourier Analysis of Spectral Lines

In many cases, the analysis of the shape of a spectral line is better done in the Fourier domain. One reason for this lies in the distribution of signal amplitude as a function of frequency as it compares to the statistically constant white-noise level. In a log-log plot, the shape of the transform is often invariant, and therefore simple horizontal translation is all that is needed to model different values of rotation rate (v sin I) or macroturbulence dispersion (z _RT). The following figure illustrates one match of a disk-integration model with observations.

I have used Fourier analysis extensively to separate the components of line broadening, the major two being rotation and macroturbulence.

Please see the following references:

• The Observation and Analysis of Stellar Photospheres, (Cambridge: Cambridge), 1992, especially Chapters 17 and 18.
• David F. Gray 1989 Astrophys. J. 347, 1021, The Rotational Break for G Giants.
• David F. Gray & R. Pallavicini 1989 Pub. Astron. Soc. Pacific 101, 695, Rotation Rates of Giants.
• Lectures on Spectral-Line Analysis: F, G, and K Stars, (The Publisher: Arva), 1988, a hard-bound book available now from me for a $15 shipping fee.
• David F. Gray & C.G. Toner 1987 Astrophys. J. 322, 360, An Analysis of the Photospheric Line Profiles in F, G, and K Supergiants.
• David F. Gray & C.G. Toner 1986 Astrophys. J. 310, 277, Rotation and Turbulence in Bright Giants.
• David F. Gray & P. Nagar 1985 Astrophys. J. 298, 756, The Rotational Discontinuity shown by Luminosity Class IV Stars.
• David F. Gray 1982 Astrophys. J. 261, 259, The Rotation of Cool Main-Sequence Stars.
• David F. Gray 1976 Solar Physics 59, 193, Turbulence in Stellar Atmospheres

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