A distant OB association around RAFGL 5475
  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 ($JHK_S$ 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.
