The young open cluster Berkeley 55

TL;DR

This study analyzes the young open cluster Berkeley 55, revealing its stellar population, age, distance, and evolutionary status, with implications for intermediate-mass star evolution.

Contribution

First detailed UBV photometry and spectral analysis of Berkeley 55, identifying its stellar content and providing insights into its age and evolutionary stage.

Findings

Age approximately 50 million years

Distance around 4 kiloparsecs

Presence of B-type, supergiant, and bright giant stars

Abstract

We present UBV photometry of the highly reddened and poorly studied open cluster Berkeley 55, revealing an important population of B-type stars and several evolved stars of high luminosity. Intermediate resolution far-red spectra of several candidate members confirm the presence of one F-type supergiant and six late supergiants or bright giants. The brightest blue stars are mid-B giants. Spectroscopic and photometric analyses indicate an age 50+-10 Myr. The cluster is located at a distance d~4kpc, consistent with other tracers of the Perseus Arm in this direction. Berkeley 55 is thus a moderately young open cluster with a sizable population of candidate red (super)giant members, which can provide valuable information about the evolution of intermediate-mass stars.