Absolute proper motion of the Galactic open cluster M67

TL;DR

This paper measures the absolute proper motion of the open cluster M67 using multi-epoch observations and galaxy references, and analyzes its galactic orbit considering different Galactic potential models.

Contribution

It provides the first precise absolute proper motion of M67 and explores its orbit within various Galactic potential configurations.

Findings

Proper motion of M67: (-9.6, -3.7) mas/yr

Cluster's galactic orbit depends on the Galactic potential model used

The study demonstrates the impact of Galactic bar and spiral arms on cluster dynamics

Abstract

We derived the absolute proper motion (PM) of the old, solar-metallicity Galactic open cluster M67 using observations collected with CFHT (1997) and with LBT (2007). About 50 galaxies with relatively sharp nuclei allow us to determine the absolute PM of the cluster. We find (mu_alpha cos(delta),mu_delta)_J2000.0 = (-9.6+/-1.1,-3.7+/-0.8) mas/yr. By adopting a line-of-sight velocity of 33.8+/-0.2 km/s, and assuming a distance of 815+/-50 pc, we explore the influence of the Galactic potential, with and without the bar and/or spiral arms, on the galactic orbit of the cluster.