Spectroscopic Confirmation of the Dragonfish Association: The Galaxy's Most Luminosity OB Association

Abstract

Young OB associations with masses greater than 10${}^4$ M$_{\sun}$ have been inferred to exist in the Galaxy but have largely evaded detection. Recently, a candidate OB association has been identified within the most luminous star forming complex in the Galaxy, the Dragonfish Nebula. We identify 18 young, massive stars with near-infrared spectroscopy from a sample of 50 members within the candidate OB association, including 15 O-type, and three Luminous Blue Variables or Wolf-Rayet stars. This number matches the expected yield of massive stars from the candidate association, confirming its existence and ability to power the parent star forming complex. These results demonstrate the existence of a 10${}^5$ M$_{\sun}$ OB association, more powerful than any previously known in the Galaxy, comparable in mass only to Westerlund 1. Further, the results also validate the color selection method used to identify the association, adding credence to others discovered in the same way.

13 pages, 3 figures, 1 table. Accepted to ApJL

References in corpus (12)

• The Infrared Telescope Facility (IRTF) Spectral Library: Cool Stars
• Star Formation Efficiencies and Lifetimes of Giant Molecular Clouds in the Milky Way
• Interstellar Extinction Law toward the Galactic Center III: J, H, Ks bands in the 2MASS and the MKO systems, and 3.6, 4.5, 5.8, 8.0 micron in the Spitzer/IRAC system
• UBVJHK synthetic photometry of Galactic O stars
• The VLT-FLAMES Tarantula Survey I: Introduction and observational overview
• The relation between the most-massive star and its parental star cluster mass
• Star Formation in Massive Clusters via the Wilkinson Microwave Anisotropy Probe and the Spitzer Glimpse Survey
• The Luminosity, Mass, and Age Distributions of Compact Star Clusters in M83 Based on HST/WFC3 Observations
• Hyperfast pulsars as the remnants of massive stars ejected from young star clusters
• The outskirts of Cygnus OB2
• Massive Star Forming Regions in the Galaxy using the Spitzer GLIMPSE Survey
• A Candidate for the Most Luminous OB Association in the Galaxy

Cited by in corpus (9)

• Spatial distribution of Galactic Wolf-Rayet stars and implications for the global population
• Unlocking Galactic Wolf-Rayet stars with $\text{Gaia}$ DR2 II: Cluster and Association membership
• Probing embedded star clusters in the HII complex NGC 6357 with VVV
• Molecular and Ionized Hydrogen in 30 Doradus. I. Imaging Observations
• On the Diagnostic Power of FIR/Sub-mm SED Fitting in Massive Galactic Molecular Clumps
• Probing the Dragonfish star-forming complex: the ionizing population of the young massive cluster Mercer 30
• High Excitation Emission Line Nebula associated with an Ultra Luminous X-ray Source at $z=$ 0.027 in the \textit{AKARI} North Ecliptic Pole Deep Field
• OB Associations at the Upper End of the Milky Way Luminosity Function
• Cloud structure and young star distribution in the Dragonfish complex