Spectroscopic study of pulsations in the atmosphere of roAp star 10 Aql

TL;DR

This study analyzes spectroscopic and photometric data of the roAp star 10 Aql, revealing pulsation frequencies, atmospheric wave components, and a pulsation node, enhancing understanding of stellar pulsations.

Contribution

It provides the first detailed spectroscopic analysis of pulsations in 10 Aql, identifying multiple frequencies and atmospheric pulsation characteristics.

Findings

Four pulsation frequencies identified, three matching photometry.

Detected a pulsation node indicated by a phase jump in RV measurements.

High amplitude RV variations observed in specific ions.

Abstract

We present the analysis of spectroscopic time-series observations of the roAp star 10 Aql. Observations were carried out in July 2006 with the UVES and SARG spectrographs simultaneously with the MOST mini-satellite photometry. All these data were analysed for radial velocity (RV) variations. About 150 lines out of the 1000 measured reveal clear pulsation signal. Frequency analysis of the spectroscopic data gives four frequencies. Three highest amplitude frequencies in spectroscopy coincide with the photometric ones. Phase-amplitude diagrams created for the lines of different elements/ions show that atmospheric pulsations may be represented by a superposition of the standing and running wave components, similar to other roAp stars. The highest RV amplitudes, 300-400 m/s, were measured for Ce II, Dy III, Tb III, and two unidentified lines at lambda 5471, 5556 A. We discovered ~0.4 period phase jump in the RV measurements across the Nd III line profiles. It indicates the presence of the pulsation node in stellar atmosphere. The phase jump occurs at nearly the same atmospheric layers for the two main frequencies. There is no rotational modulation in the average spectra for the 6 different nights we analysed.