The putative old, nearby cluster Lod\'{e}n 1 does not exist

TL;DR

This study thoroughly investigated Lodén 1, a purported nearby 2 Gyr old cluster, and found no evidence supporting its existence as a true star cluster, suggesting it is neither old nor nearby.

Contribution

The paper provides a comprehensive analysis combining archival data and new spectroscopic observations to disprove the existence of Lodén 1 as a genuine star cluster.

Findings

No main-sequence turnoff or red giant branch detected.

No kinematic clustering found among candidate members.

Lodén 1 is not an actual star cluster.

Abstract

Astronomers have access to precious few nearby, middle-aged benchmark star clusters. Within 500 pc, there are only NGC 752 and Ruprecht 147 (R147), at 1.5 and 3 Gyr respectively. The Database for Galactic Open Clusters (WEBDA) also lists Lod\'{e}n 1 as a 2 Gyr cluster at a distance of 360 pc. If this is true, Lod\'{e}n 1 could become a useful benchmark cluster. This work details our investigation of Lod\'{e}n 1. We assembled archival astrometry (PPMXL) and photometry (2MASS, Tycho-2, APASS), and acquired medium resolution spectra for radial velocity measurements with the Robert Stobie Spectrograph (RSS) at the Southern African Large Telescope. We observed no sign of a cluster main-sequence turnoff or red giant branch amongst all stars in the field brighter than $J < 11$. Considering the 29 stars identified by L.O. Lod\'{e}n and listed on SIMBAD as the members of Lod\'{e}n 1, we found no compelling evidence of kinematic clustering in proper motion or radial velocity. Most of these candidates are A stars and red giants, and their observed properties are consistent with distant field stars in the direction of Lod\'{e}n 1 in the Galactic plane. We conclude that the old nearby cluster Lod\'{e}n 1 is neither old, nor nearby, nor a cluster.