Gas Kinematics and Star Formation in the Filamentary IRDC G34.43+0.24
  We performed a multiwavelength study toward infrared dark cloud (IRDC)
G34.43+0.24. New maps of 13CO $J$=1-0 and C18}O J=1-0 were obtained from the
Purple Mountain Observatory (PMO) 13.7 m radio telescope. At 8 um (Spitzer -
IRAC), IRDC G34.43+0.24 appears to be a dark filament extended by 18 arcmin
along the north-south direction. Based on the association with the 870 um and
C18O J=1-0 emission, we suggest that IRDC G34.43+0.24 should not be 18 arcmin
in length, but extend by 34 arcmin. IRDC G34.43+0.24 contains some massive
protostars, UC H II regions, and infrared bubbles. The spatial extend of IRDC
G34.43+0.24 is about 37 pc assuming a distance of 3.7 kpc. IRDC G34.43+0.24 has
a linear mass density of 1.6*10^{3} M_{sun} pc^{-1}, which is roughly
consistent with its critical mass to length ratio. The turbulent motion may
help stabilizing the filament against the radial collapse. Both infrared
bubbles N61 and N62 show a ringlike structure at 8 um. Particularly, N61 has a
double-shell structure, which has expanded into IRDC G34.43+0.24. The outer
shell is traced by 8 um and 13}CO J=1-0 emission, while the inner shell is
traced by 24 um and 20 cm emission. We suggest that the outer shell (9.9*10^{5}
yr) is created by the expansion of H II region G34.172+0.175, while the inner
shell (4.1-6.3*10^{5} yr) may be produced by the energetic stellar wind of its
central massive star. From GLIMPSE I catalog, we selected some Class I sources
with an age of 10^{5} yr. These Class I sources are clustered along the
filamentary molecular cloud.
