A distant OB association around RAFGL 5475

Abstract

Observations of the galactic disk at mid-infrared and longer wavelengths reveal a wealth of structures indicating the existence of complexes of recent massive star formation. However, little or nothing is known about the stellar component of those complexes. We have carried out observations aiming at the identification of early-type stars in the direction of the bright infrared source RAFGL~5475, around which several interstellar medium structures usually associated with the presence of massive stars have been identified. Our observations have the potential of revealing the suspected but thus far unknown stellar component of the region around RAFGL~5475. We have carried out near-infrared imaging observations ($JH{K}_S$ bands) designed to reveal the presence of early-type stars based on their positions in color-color and color-magnitude diagrams centered on the location of RAFGL~5475. We took into account the possibility that candidates found might belong to a foreground population physically related either to M16 or M17, two giant HII regions lying midway between the Sun and RAFGL~5475. The near-infrared color-color diagram shows clear evidence for the presence of a moderately obscured population of early-type stars in the region imaged. By studying the distribution of extinction in their direction and basic characteristics of the interstellar medium we show that these new early-type stars are most likely associated with RAFGL~5475. By investigating the possible existence of massive early-type stars in the direction of RAFGL~5475 we have discovered the existence of a new OB association. A very preliminary assessment of its contents suggests the presence of several O-type stars, some of them likely to be associated with structures in the interstellar medium. The new association is located at 4 kpc from the Sun in the Scutum-Centaurus arm.

arXiv comment8 pages, 7 figures; accepted by Astronomy and Astrophysics

References in corpus (18)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• The Milky Way in Molecular Clouds: A New Complete CO Survey
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• VISTA Variables in the Via Lactea (VVV): The public ESO near-IR variability survey of the Milky Way
• The Third US Naval Observatory CCD Astrograph Catalog (UCAC3)
• The initial conditions of stellar protocluster formation. I. A catalogue of Spitzer dark clouds
• Galactocentric Distance With the OGLE and Hipparcos Red Clump Stars
• The Green Bank Telescope HII Region Discovery Survey II. The Source Catalog
• A general catalogue of 6.7 GHz methanol masers. I: data
• Resolution of the Distance Ambiguity for Galactic HII Regions
• Detection of the old stellar component of the major Galactic bar
• The Long Bar in the Milky Way. Corroboration of an old hypothesis
• The Bolocam Galactic Plane Survey V: HCO+ and N2H+ Spectroscopy of 1.1 mm Dust Continuum Sources
• The Becklin-Neugebauer Object as a Runaway B Star, Ejected 4000 years ago from the theta^1C system
• The Bolocam Galactic Plane Survey. X. A Complete Spectroscopic Catalog of Dense Molecular Gas Observed toward 1.1 mm Dust Continuum Sources with 7.5 <= l <= 194 degrees
• The outskirts of Cygnus OB2
• PANIC: the new panoramic NIR camera for Calar Alto

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