# K2 Observations of 95 Vir: delta Scuti Pulsations in a Chromospherically Active Star

## TL;DR

This study analyzes Kepler K2 data of the active star 95 Vir, identifying delta Scuti pulsations and exploring the origin of low-frequency variability, suggesting rotational modulation due to star spots as the most likely cause.

## Contribution

It provides the first detailed analysis of 95 Vir's pulsational and rotational variability using K2 data, linking chromospheric activity with pulsation characteristics.

## Key findings

- Main pulsation frequency at 9.53728 d^-1 identified as delta Scuti pulsation.
- Low-frequency signal at 1.07129 d^-1 likely due to rotational modulation from star spots.
- Evidence favors rotational origin for the low-frequency variability, consistent with chromospheric activity.

## Abstract

We have searched for photometric variability in 95 Vir, a fast rotating, chromospherically active early F-type star, which was observed in the framework of Campaign 6 of the Kepler K2 mission. Available literature information on 95 Vir were procured, and well-established calibrations were employed to verify the derived astrophysical parameters. We have investigated the location of our target star in the M(Bol) versus log T(eff) diagram, which provides information on evolutionary status. We have discussed our results in detail, drawing on literature information and the theoretical predictions of state-of-the-art pulsation models, with the aim of unraveling the underlying variability mechanisms. From an analysis of 3400 long-cadence measurements, we have identified two main frequencies and several harmonics in our target star. We attribute the main frequency, f1 = 9.53728 d**-1, to delta Scuti pulsations. The origin of the secondary signal, f2 = 1.07129 d**-1, is less clear. We have investigated three possible interpretations of the low-frequency variation: binarity, pulsation and rotational modulation. Current evidence favours an interpretation of f2 as a signature of the rotational period caused by the presence of cool star spots, which goes along well with the observed chromospheric activity. However, phase-resolved spectroscopy is needed to verify this assumption. We briefly consider other chromospherically active delta Scuti stars that have been presented in the literature. A search for star spot-induced photometric variability in these objects might be of great interest, as well as an investigation of the interplay between chromospheric and pulsational activity.