Precise parameter determination of the open cluster NGC 1647 via asteroseismology of p-mode pulsators

TL;DR

This study uses asteroseismology of pulsating stars in NGC 1647 to precisely determine the cluster's age and metallicity, improving upon previous estimates and demonstrating the method's diagnostic power.

Contribution

It provides the first detailed asteroseismic analysis of NGC 1647, refining its age and metallicity with high precision and establishing a benchmark for future cluster studies.

Findings

Seventy-six cluster members identified with high confidence.

Seismic age of 178+11-9 Myr, more precise than previous estimates.

Metallicity determined as [Fe/H] = -0.08+0.04-0.01.

Abstract

Asteroseismology of member pulsators provides a robust physical constraint on cluster parameters by linking internal stellar structures to the global properties of the host cluster. However, the parameters of NGC 1647 remains poorly constrained due to limited investigation, a situation that cluster asteroseismology can significantly refine. In this study, we identified 271 high confidential cluster members in NGC 1647, using HDBSCAN clustering with radial-velocity validation. Its initial age is determined in the range of 1250-280 Myr, derived from isochrone fitting based on multi-survey metallicities extinction-corrected Gaia photometry. Among the members, we found 96 periodic variables from TESS and K2 photometry, including nine p-mode pulsators (five {\delta} Sct and four hybrid {\delta} Sct-{\gamma} Dor stars). Assuming a common cluster age and initial chemical composition, joint asteroseismic modeling is performed based on measured large frequency separations and individual mode frequencies. This yields a metallicity of [Fe/H] = -0.08+0.04-0.01, well consistent with the spectroscopic determinations, and a seismic age of 178+11-9 Myr, more precise than isochrone-based estimates. This work shows the diagnostic potential of {\delta} Sct asteroseismology in young open clusters and establishes a high-precision benchmark for future studies of NGC 1647 and other open clusters.