Dynamical properties and search of variable stars: NGC 1960

TL;DR

This study investigates the dynamical properties, mass functions, and variable star population in the open cluster NGC 1960, revealing mass segregation, a near-normal extinction law, and a high variability fraction among massive stars.

Contribution

It provides new photometric analysis of variable stars in NGC 1960, including period determination and classification, and examines the cluster's dynamical state and mass segregation.

Findings

Mass function slope is close to Salpeter value.

Evidence of mass segregation without full dynamical relaxation.

High variability fraction among massive stars.

Abstract

The total-to-selective extinction RV in the direction of a cluster is found to be 3.12 +/- 0.2 (close to its normal value). We derive the luminosity and mass functions for the cluster main sequence stars. The mass function slope is found to be -2.29 +/- 0.20 which is close to Salpeter value. We find evidence of mass segregation process in the cluster which is not yet dynamically relaxed. We have performed time series photometric observations to detect variable stars within star cluster NGC 1960. The DAOPHOT-II package is utilized to estimate the apparent stellar magnitudes of stars. The secondary standardization method is applied to the transformation of these apparent magnitudes into standard values. The magnitude-time diagrams (light curves) of stars are constructed to identify possible variability nature within them. The stars, having sufficient magnitude variation with time, are considered to be variable stars and their period values have computed through PERIOD04 package. These periodic values of variables are used to construct their corresponding phase diagrams. Here, we are reporting short periodic variables through the photometric analysis of science frames of whole night observations. Their type and variability nature, have been prescribed on the basis of information about amplitude, period and shape of phase diagrams. The location of variables on colour-magnitude-diagram is effective to constrain the history of stellar evolution. Our present analysis indicates that the variability fraction of massive stars is found to be high in the comparison of lighter members.