The distance and neutral environment of the massive stellar cluster Westerlund 1

Abstract

The goal of this study is to determine a distance to Westerlund 1 independent of the characteristics of the stellar population and to study its neutral environment, using observations of atomic hydrogen. The HI observations are taken from the Southern Galactic Plane Survey to study HI absorption in the direction of the HII region created by the members of Westerlund 1 and to investigate its environment as observed in the HI line emission. A Galactic rotation curve was derived using the recently revised values for the Galactic centre distance of $R_{\odot }=7.6$ kpc, and the velocity of the Sun around the Galactic centre of ${\Theta }_{\odot }=214$ km s${}^{-1}$. The newly determined rotation model leads us to derive a distance of $3.9\pm 0.7$ kpc to Westerlund 1, consistent with a location in the Scutum-Crux Arm. Included in this estimate is a very careful investigation of possible sources of error for the Galactic rotation curve. We also report on small expanding HI features around the cluster with a maximum dynamic age of 600,000 years and a larger bubble which has a minimum dynamic age of 2.5 million years. Additionally we re-calculated the kinematic distances to nearby HII regions and supernova remnants based on our new Galaxic rotation curve. We propose that in the early stages of the development of Wd 1 a large interstellar bubble of diameter about 50 pc was created by the cluster members. This bubble has a dynamic age similar to the age of the cluster. Small expanding bubbles, with dynamical ages $\sim 0.6$ Myr are found around Wd 1, which we suggest consist of recombined material lost by cluster members through their winds.

arXiv comment8 pages, accepted for publication in A&A

References in corpus (15)

• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• SINFONI in the Galactic Center: young stars and IR flares in the central light month
• First GLIMPSE Results on the Stellar Structure of the Galaxy
• The VLA Galactic Plane Survey
• The Southern Galactic Plane Survey: HI Observations and Analysis
• Massive Stars in the Quintuplet Cluster
• Galactic Kinematics of Cepheids from Hipparcos Proper Motions
• Massive Stars in the Arches Cluster
• On the massive stellar population of the Super Star Cluster Westerlund 1
• A Neutron Star with a Massive Progenitor in Westerlund 1
• A census of the Wolf-Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy
• The Molonglo Galactic Plane Survey: I. Overview and Images
• The Galactic Distribution of Large HI Shells
• A hidden population of Wolf-Rayet stars in the massive galactic cluster Westerlund 1
• Discovery of extended radio emission in the young cluster Wd1

Cited by in corpus (68)

• The McGill Magnetar Catalog
• The strongest cosmic magnets: Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars
• A massive cluster of Red Supergiants at the base of the Scutum-Crux arm
• The RMS Survey: Critical Tests of Accretion Models for the Formation of Massive Stars
• Intermediate to low-mass stellar content of Westerlund 1
• Spatial distribution of Galactic Wolf-Rayet stars and implications for the global population
• The cool supergiant population of the massive young star cluster RSGC1
• Discovery of extended VHE γ-ray emission from the vicinity of the young massive stellar cluster Westerlund 1
• The population of OB supergiants in the starburst cluster Westerlund 1
• MN48: a new Galactic bona fide luminous blue variable revealed by Spitzer and SALT
• Mass segregation and elongation of the starburst cluster Westerlund 1
• On the shape of the spectrum of cosmic-rays accelerated inside superbubbles
• The G305 star-forming complex: the central star clusters Danks 1 and Danks 2
• Magnetar Broadband X-ray Spectra Correlated with Magnetic Fields: Suzaku Archive of SGRs and AXPs Combined with NuSTAR, Swift, and RXTE
• A newly-discovered young massive star cluster at the end of the Galactic Bar
• The Starburst Cluster Westerlund 1: The Initial Mass Function and Mass Segregation
• 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?
• A guided map to the Spiral arms in the galactic disk of the Milky Way
• Distances, Radial Distribution and Total Number of Galactic Supernova Remnants
• Is the massive young cluster Westerlund I bound?
• NuSTAR Discovery of a Young, Energetic Pulsar Associated with the Luminous Gamma-ray Source HESS J1640-465
• The Mipsgal View of Supernova Remnants in the Galactic Plane
• A deep spectromorphological study of the $\gamma$-ray emission surrounding the young massive stellar cluster Westerlund 1
• The very low-mass stellar content of the young supermassive Galactic star cluster Westerlund 1
• A search for new supernova remnant shells in the Galactic plane with H.E.S.S
• Radio and X-ray images of SNR G18.8+0.3 interacting with molecular clouds
• Radio emission from the massive stars in the Galactic Super Star Cluster Westerlund 1
• Discovery of the hard spectrum VHE gamma-ray source HESS J1641-463
• A Catalogue of Galactic Supernova Remnants in the far-infrared: revealing ejecta dust in pulsar wind nebulae
• The JCMT 12CO(3-2) Survey of the Cygnus X Region: I. A Pathfinder
• The Optical/Near-Infrared Extinction Law In Highly Reddened Regions
• AMI observations of northern supernova remnants at 14-18 GHz
• Discovery of a young massive stellar cluster near HESS J1813-178
• The Fundamental Parameters of Four Massive Eclipsing Binaries in Westerlund 1
• Fundamental Parameters of four Massive Eclipsing Binaries in Westerlund 1
• Understanding the TeV $\gamma$-ray emission surrounding the young massive star cluster Westerlund 1
• The distances to star-clusters hosting Red Supergiants: $\chi$ Per, NGC 7419, and Westerlund 1
• An ALMA 3mm continuum census of Westerlund 1
• G141.2+5.0, a new Pulsar Wind Nebula discovered in the Cygnus Arm of the Milky Way
• A Complete Catalogue of Dusty Supernova Remnants
• Open cluster stability and the effects of binary stars
• Westerlund 1 under the light of Gaia EDR3: Distance, isolation, extent, and a hidden population
• The Quintuplet Cluster: Extended Structure and Tidal Radius
• Water Maser Survey on AKARI and IRAS Sources: A Search for "Low-Velocity" Water Fountains
• Where are the magnetar binary companions? Candidates from a comparison with binary population synthesis predictions
• Inferring the parallax of Westerlund 1 from Gaia DR2
• Interstellar gas towards the TeV gamma-ray sources HESS J1640-465 and HESS J1641-463
• Distance and age of the massive stellar cluster Westerlund 1. I. Parallax method using Gaia-EDR3
• Maser Observations of Westerlund 1 and Comprehensive Considerations on Maser Properties of Red Supergiants Associated with Massive Clusters
• Dense molecular gas at 12 mm towards Galactic TeV gamma-ray sources
• YSO jets in the Galactic Plane from UWISH2: IV - Jets and outflows in Cygnus-X
• Maser and Infrared Studies of Oxygen-Rich Late/Post-AGB Stars and Water Fountains: Development of a New Identification Method
• HESS J1640-465 and HESS J1641-463: two intriguing TeV sources in the light of new Fermi LAT observations
• A Complete Atlas of HI Absorption toward HII Regions in the Southern Galactic Plane Survey (SGPS1)
• The multi-outburst activity of the magnetar in Westerlund I
• A Radio Census of the Massive Stellar Cluster Westerlund 1
• Properties of shocked dust grains in supernova remnants
• Constraining the origin of the puzzling source HESS J1640-465 and the PeVatron candidate HESS J1641-463 using Fermi-LAT observations
• The Age Evolution of the Radio Morphology of Supernova Remnants
• Multiwavelength Observations of Massive Stellar Cluster Candidates in the Galaxy
• The enormous outer Galaxy HII region CTB 102
• The discovery of a molecular cavity in the Norma near arm associated to H.E.S.S gamma-ray source located in the direction of Westerlund 1
• TRAPUM search for pulsars in supernova remnants and pulsar wind nebulae -- I. Survey description and initial discoveries
• Fast as Potoroo: Radio Continuum Detection of a Bow-Shock Pulsar Wind Nebula Powered by Pulsar J1638-4713
• 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
• A cosmic-ray loaded nascent outflow driven by a massive star cluster
• On the hadronic origin of the very high energy $\gamma$-ray emission surrounding the young massive stellar cluster Westerlund 1