Variable stars in one open cluster within the Kepler/K2-Campaign-5 field: M 67 (NGC 2682)

TL;DR

This study presents a detailed photometric catalogue of the open cluster M 67, identifying 68 variable stars, including 43 new detections, and improves data on variable periods and proper motions, aiding future Kepler/K2 and radial-velocity surveys.

Contribution

The paper provides a new high-resolution photometric catalogue of M 67 with improved variable star data, supporting upcoming space and radial-velocity exoplanet surveys.

Findings

Detected 68 variable stars, 43 newly identified

Enhanced proper-motion and period measurements

Catalogue will support Kepler/K2 and radial-velocity studies

Abstract

In this paper we continue the release of high-level data products from the multiyear photometric survey collected at the 67/92 cm Schmidt Telescope in Asiago. The primary goal of the survey is to discover and to characterise variable objects and exoplanetary transits in four fields containing five nearby open clusters spanning a broad range of ages. This second paper releases a photometric catalogue, in five photometric bands, of the Solar-age, Solar-metallicity open cluster M 67 (NGC 2682). Proper motions are derived comparing the positions observed in 2013 at the Asiago's Schmidt Telescope with those extracted from WFI@2.2m MPG/ESO images in 2000. We also analyse the variable sources within M 67. We detected 68 variables, 43 of which are new detection. Variable periods and proper-motion memberships of a large majority of sources in our catalogue are improved with respect to previous releases. The entire catalogue will be available in electronic format. Besides the general interest on an improved catalogue, this work will be particularly useful because of: (1) the imminent release of Kepler/K2 Campaign-5 data of this cluster, for which our catalogue will provide an excellent, high spatial resolution input list, and (2) characterisation of the M 67 stars which are targets of intense HARPS and HARPS-N radial-velocity surveys for planet search.