Fourier analysis of Fe I lines in the spectra of the Sun, {\alpha} Centauri A, Procyon, Arcturus, and Canopus

TL;DR

This study employs Fourier analysis of high-resolution Fe I spectral lines to measure micro and macroturbulent velocities and rotation speeds in the atmospheres of the Sun and several stars, revealing different velocity field characteristics.

Contribution

It introduces a detailed Fourier analysis method to determine turbulent velocities and rotation in stellar atmospheres, including anisotropic turbulence in Canopus, expanding previous models.

Findings

Microturbulent velocities are around 0.8 km/s for Sun and similar stars.

Macroturbulent velocities vary from 2.6 km/s in the Sun to 17 km/s in Canopus.

Rotation velocity of Canopus is approximately 3.5 km/s.

Abstract

We used spectral observations of Fe I line profiles with a 200 000 resolution to determine micro and macroturbulent velocities in the atmospheres of the Sun as a star, {\alpha} Cen A, Procyon ({\alpha} CMi), Arcturus ({\alpha} Boo), and Canopus ({\alpha} Car). Isotropic microturturbulent velocities (V_mi) and radial-tangential macroturbulent velocities (V_ma,RT) were found to be a quite suitable approximation to the velocity field in the atmospheres of all stars studied except Canopus. The average velocities V_mi and V_ma,RT are 0.8 +/- 0.1 and 2.6 +/- 0.3 km/s for the Sun as a star, 0.8 +/- 0.2 and 2.9 +/- 0.4 km/s for {\alpha} Cen A, 0.8 +/- 0.3 and 5.9 +/- 0.2 km/s for Procyon, 1.0 +/- 0.2 and 4.6 +/- 0.3 km/s for Arcturus. The velocity field in the atmosphere of Canopus can be described by an anisotropic radial-tangential distribution of microturbulence with V_mi,RT = 2.1 km/s and anisotropic distribution of macroturbulence with V_ma,rad = 17 +/- 2 km/s and V_ma,tan = 1.3 +/- 1.0 km/s. From Fourier analysis of broadening and shapes of three spectral lines of Fe I, we have derived the rotation velocity V_e sini = 3.5 +/- 0.2 km/s for Canopus.