Gamma Equ - magnetic roAp star

Please use this DOI to cite the data:

doi:10.17876/data/2024_1

The data were published with this article:

Järvinen et al. (2024), A&A 683, A66

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Contact

Silva Järvinen
Leibniz-Institute for Astrophysics Potsdam (AIP)
sjarvinen AT aip.de

Testing pulsation diagnostics in the rapidly oscillating magnetic Ap star γ Equ using near-infrared CRIRES+ observations

by Järvinen et al. (2024), A&A 683, A66

Abstract

Pulsations of rapidly oscillating Ap stars and their interaction with the stellar magnetic field have not been studied in the near-infrared (near-IR) region despite the benefits these observations offer compared to visual wavelengths. The main advantage of the near-IR is the quadratic dependence of the Zeeman effect on the wavelength, as opposed to the linear dependence of the Doppler effect. To test pulsation diagnostics of roAp stars in the near-IR, we aim to investigate the pulsation behaviour of one of the brightest magnetic roAp stars, γ Equ, which possesses a strong surface magnetic field of the order of several kilogauss and exhibits magnetically split spectral lines in its spectra. Two magnetically split spectral lines belonging to different elements, the triplet Fe I at 1563.63 nm and the pseudo-doublet Ce III at 1629.2 nm, were recorded with CRIRES+ over about one hour in the H band with the aim of understanding the character of the line profile variability and the pulsation behaviour of the magnetic field modulus. The profile shapes of both studied magnetically split spectral lines vary in a rather complex manner probably due to a significant decrease in the strength of the longitudinal field component and an increase in the strength of the transverse field components over the last decade. A mean magnetic field modulus of 3.9 kG was determined for the Zeeman triplet Fe I at 1563.63 nm, whereas for the pseudo-doublet Ce III at 1629.2 nm we observe a much lower value of only about 2.9 kG. For comparison, a mean field modulus of 3.4 kG was determined using the Zeeman doublet Fe II at 6249.25 in optical PEPSI spectra recorded just about two weeks before the CRIRES+ observations. Different effects that may lead to the differences in the field modulus values are discussed. Our measurements of the mean magnetic field modulus using the line profiles recorded in different pulsational phase bins suggest a field modulus variability of 32 G for the Zeeman triplet Fe I at 1563.63 nm and 102 G for the pseudo-doublet Ce III at 1629.2 nm.

Data available download

pepsir.20170911.005.sxs.i.fits : PEPSI Stokes I spectrum of γ Equ obtained 2017 Sep 11 covering wavelength range 5384-6297 angstroms. The binary fits file has the wavelegths (in angstroms), the normalised intensity values, and the variances.

pepsir.20201203.000.dxs.i.fits : PEPSI Stokes I spectrum of γ Equ obtained 2020 Dec 3 covering wavelength range 6271-7429 angstroms. The binary fits file has the wavelegths (in angstroms), the normalised intensity values, and the variances.

pepsib.20220915.060.dxs.i.fits : PEPSI Stokes I spectrum of γ Equ obtained 2022 Sep 15 covering wavelength range 4236-4771 angstroms. The binary fits file has the wavelegths (in angstroms), the normalised intensity values, and the variances.

pepsir.20220915.055.dxs.i.fits : PEPSI Stokes I spectrum of γ Equ obtained 2022 Sep 15 covering wavelength range 5390-6289 angstroms. The binary fits file has the wavelegths (in angstroms), the normalised intensity values, and the variances.