Test of depending frequencies of the variable Stars of OC: NGC 6866

TL;DR

This study investigates secondary pulsation modes in variable stars of NGC 6866, identifying their frequency-amplitude characteristics and proposing new correlations with stellar parameters, challenging previous classifications of certain variables.

Contribution

It provides the first detailed analysis of depending frequencies of variable stars in NGC 6866 and introduces a new correlation between secondary pulsation modes and absolute magnitude.

Findings

18 out of 28 variables show secondary pulsation modes

Field variables are likely red-component-stars (RCS)

No support found for HADS characteristics in known HADS stars

Abstract

The search of secondary pulsations is carried out to understand the possible relations among the known parameters of variables of the cluster, NGC 6866. These pulsations arise due to the various ongoing physical phenomena of the variables. Moreover, pulsations of the variables are identified through the visual inspection of their frequency-amplitude distributions. A total of 18 variables among the 28 known variables are showing the secondary pulsation modes. Furthermore, these pulsation modes do not occur for PV, EA, EB, Elliptical and semi-regular. In addition, the field variables seem to be the red-component-stars (RCS) for the studied cluster. The smoothness of the frequency-amplitude curves, signal to noise ratio and the significant limits are play major role for deciding the real peak or frequency values. We are not rejected those amplitude peak of parabolic patterns, for which, the amplitude is greater than then significant limit of variables. The weight of pulsation frequencies is given to be 0.5 for non full cyclic variation but the amplitude is greater than significant limit. Similarly, our present analysis does not support the HADS characteristics of previous known HADS stars within stellar cluster NGC 6866. We are also proposed to new correlation between the secondary pulsation modes (depending frequencies) and the absolute magnitude of known variables.