Distance and age of the massive stellar cluster Westerlund 1. I. Parallax method using Gaia-EDR3

Abstract

Westerlund 1 (Wd 1) is one of the most massive young star clusters in the Milky Way. Although relevant for star formation and evolution, its fundamental parameters are not yet very well constrained. We aim to derive an accurate distance and provide constraints on the cluster age. We used the photometric and astrometric information available in the Gaia Early Data Release 3 (Gaia-EDR3) to infer its distance of 4.06${}_{-0.34}^{+0.36}$ kpc. Modelling of the eclipsing binary system W36, reported in Paper II, led to the distance of 4.03$\pm$0.25 kpc, in agreement with the Gaia-EDR3 distance and, therefore, validating the parallax zero-point correction approach appropriate for red objects. The weighted average distance based on these two methods results in d${}_{wd1}$=4.05$\pm$0.20 kpc ($m-M$=13.04${}_{-0.12}^{+0.11}$ mag), which has an unprecedented accuracy of 5%. Using the Binary Population and Spectral Synthesis (BPASS) models for the Red Supergiants with solar abundance, we derived an age of 10.7$\pm$1 Myr, in excellent agreement with recent work by Beasor & Davies (10.4${}_{-1.2}^{+1.3}$ Myr) based on MIST evolutionary models. In Paper II, the age of W36B was reported to be 6.4$\pm$0.5 Myr, supporting recent claims of a temporal spread of several Myrs for the star-forming process within Wd 1 instead of a single monolithic starburst episode scenario.

16 pages, 9 figures, accepted for publication at MNRAS on August 18th, 2022

References in corpus (20)

• Binary interaction dominates the evolution of massive stars
• GW190521: A Binary Black Hole Merger with a Total Mass of $150M_{\odot }$
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• The Second-Generation Guide Star Catalog: Description and Properties
• A census of the Wolf-Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy
• The Initial Masses of the Red Supergiant Progenitors to Type-II Supernovae
• Intermediate to low-mass stellar content of Westerlund 1
• The cool supergiant population of the massive young star cluster RSGC1
• The distance and neutral environment of the massive stellar cluster Westerlund 1
• A VLT/FLAMES survey for massive binaries in Westerlund 1. IV. Wd1-5 - binary product and a pre-supernova companion for the magnetar CXOU J1647-45?
• Extinction law in the range 0.4-4.8 $\mu$m and the 8620 $\mathring{A}$ DIB towards the stellar cluster Westerlund 1
• Grids of stellar models with rotation VII: Models from 0.8 to 300 M${}_{\odot }$ at super-solar metallicity (Z = 0.020)
• A Rich Population of X-ray Emitting Wolf-Rayet Stars in the Galactic Starburst Cluster Westerlund 1
• The Age of Westerlund 1 Revisited
• Unlocking Galactic Wolf-Rayet stars with $\text{Gaia}$ DR2 II: Cluster and Association membership
• The distances to star-clusters hosting Red Supergiants: $\chi$ Per, NGC 7419, and Westerlund 1
• Gaia-DR2 distance to the W3 Complex in the Perseus Arm
• A VLT/FLAMES survey for massive binaries in Westerlund 1: VIII. Binary Systems and Orbital Parameters
• A VLT/FLAMES survey for massive binaries in Westerlund 1: VI. Properties of X-ray bright massive cluster members
• On aging star clusters using red supergiants independent of the fraction of interacting binary stars

Cited by in corpus (5)

• Distance and age of the massive stellar cluster Westerlund 1. II. The eclipsing binary W36
• eROSITA X-ray Analysis of the PeVatron Candidate Westerlund 1
• Don't believe the hype(r): The Yellow Supergiants of Westerlund 1
• A cosmic-ray loaded nascent outflow driven by a massive star cluster
• Structure and Dynamics of the Young Massive Star Cluster Westerlund 1