Fourier Analysis of Spectra of Solar-Type Stars

TL;DR

This paper applies Fourier transform techniques to analyze spectral lines of solar-type stars, accurately determining microturbulent, macroturbulent, and rotation velocities, and comparing results with other methods.

Contribution

The study demonstrates the effectiveness of Fourier analysis in distinguishing and measuring velocities in slowly rotating solar-type stars, including complex cases.

Findings

Average velocities for the Sun: microturbulent 0.85 km/s, macroturbulent 2.22 km/s, rotation 1.75 km/s.

Macroturbulent velocity decreases with atmospheric height in the Sun and HD 1835.

Fourier techniques yield reliable velocity measurements for slowly rotating stars.

Abstract

We used Fourier transform techniques to determine macroturbulent velocity. The analysis is done with mictoturbulent velocity and rotation velocity as an unknown quantities. In order to distinguish the effects of rotation from macroturbulence effects in slowly rotating stars, primarily the main lobe of residual Fourier transforms of the observed lines, which were taken from the solar spectrum and the spectra of two other stars, was used. This case of Fourier analysis of spectral lines is the most complicated one. The end results were in a satisfactory agreement with the data obtained using different methods. We have obtained the average values of microturbulent, macroturbulent, and rotation velocities were 0.85, 2.22, and 1.75 km/s for the Sun as the star, 0.58, 1.73, and 0.78 km/s for HD 10700, and 1.16, 3.56, and 6.24 km/s for HD 1835. It was found that the macroturbulent velocity decreases with height in the atmosphere of the Sun and HD 1835. In the case of HD 10700, the macroturbulent velocity did not change with height, and the determined rotation velocity was two times lower than the one obtained using other methods. It was concluded that Fourier transform techniques are suitable for determining the velocities in atmospheres of solar-type stars with very slow rotation.