Discovery of a young massive stellar cluster near HESS J1813-178

Abstract

We present the serendipitous discovery of a young stellar cluster in the Galactic disk at l=12deg. Using Keck/NIRSPEC, we obtained high- and low-resolution spectroscopy of several stars in the cluster, and we identified one red supergiant and two blue supergiants. The radial velocity of the red supergiant provides a kinematic cluster distance of 4.7pm0.4 kpc, implying luminosities of the stars consistent with their spectral types. Together with the known Wolf-Rayet star located 2.4' from the cluster center, the presence of the red supergiant and the blue supergiants suggests a cluster age of 6-8 Myr, and an initial mass of 2000 Msun. Several stars in the cluster are coincident with X-ray sources, including the blue supergiants and the Wolf-Rayet star. This is indicative of a high binary fraction, and is reminiscent of the massive young cluster Westerlund 1. The cluster is coincident with two supernova remnants, SNR G12.72-0.0 and G12.82-0.02, and the highly magnetized pulsar associated with the TeV gamma-ray source HESS J1813-178. The mixture of spectral types suggests that the progenitors of these objects had initial masses of 20 - 30 Msun.

4 pages, 3 figures. ApJ Letter, accepted. Figure 2 has been revised

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Cited by in corpus (9)

• The death of massive stars - I. Observational constraints on the progenitors of type II-P supernovae
• First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
• Discovery of a Highly Energetic X-ray Pulsar Powering HESS J1813-178 in the Young Supernova Remnant G12.82-0.02
• A catalog of known Galactic K-M stars of class I, candidate RSGs, in Gaia DR2
• Massive Stars in the W33 Giant Molecular Complex
• Red Supergiant Candidates for Multimessenger Monitoring of the Next Galactic Supernova
• Radio Detection of PSR J1813-1749 in HESS J1813-178: The Most Scattered Pulsar Known
• Galactic Observatory Science with the ASTRI Mini-Array at the Observatorio del Teide
• Massive Stars in Molecular Clouds Rich in High-energy Sources: The Bridge of G332.809-0.132 and CS 78 in NGC 6334