Gas Kinematics and Star Formation in the Filamentary Irdc G34.43+0.24

Abstract

We performed a multiwavelength study toward the infrared dark cloud (IRDC) G34.43+0.24. New maps of 13 CO J = 1-0 and C 18 O J = 1-0 were obtained from the Purple Mountain Observatory (PMO) 13.7 m radio telescope. At 8 μm (Spitzer-IRAC), IRDC G34.43+0.24 appears to be a dark filament extended by 18′ along the north-south direction. Based on the association with the 870 μm and C 18 O J = 1-0 emission, we suggest that IRDC G34.43+0.24 should not be 18′ in length, but extend to 34′. 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×103 M e pc −1 , which is roughly consistent with its critical mass to length ratio. The turbulent motion may help stabilize the filament against the radial collapse. Both infrared bubbles N61 and N62 show a ringlike structure at 8 μm. In particular, N61 has a double-shell structure that has expanded into IRDC G34.43+0.24. The outer shell is traced by 8 μm and 13 CO J = 1-0 emission, while the inner shell is traced by 24 μm and 20 cm emission. We suggest that the outer shell (9.9×10 5 years) is created by the expansion of H II region G34.172+0.175, while the inner shell (4.1∼6.3×10 5 years) may be produced by the energetic stellar wind of its central massive star. From the GLIMPSE I catalog, we selected some Class I sources with an age of ∼10 5 years. These Class I sources are clustered along the filamentary molecular cloud.

A Molecular Line Investigation of the Interaction between Mid-infrared Bubbles and the Interstellar Medium

“…N62 was included in the sample of MIR bubbles studied by Deharveng et al (2010), who noted that it was coincident with 21 cm radio emission, detected in the ATLASGAL survey, and coincident with an infrared dark cloud (IRDC). N62 is coincident with HII region G34.325+0.211 (Anderson et al 2011), andXu et al (2016) conducted an analysis of the ionizing flux from this HII region to determine that the spectral type of the ionizing star is between B1V and B1.5V. The HII region velocities reported by (Anderson et al 2011) are consistent with the CS (1-0) velocities of the dense gas detected in Watson et al (2016) and in this paper, indicating that the IRDC is indeed at the same distance as, and associated with, N62.…”

Histogram of oriented gradients: a technique for the study of molecular cloud formation

“…The deviation from the clustering of high V values around v HI ≈ v 13CO is more evident toward GRS34.19+0.05. There, the broad range of velocities with large V can in principle be related to the effects of the Hii regions G34.256+0.136 and G34.172+0.175 and the presence of infrared bubbles (Churchwell et al 2006;Xu et al 2016). It is worth noting that observationally, the MCs are arbitrarily defined identities, the spatial and velocity associations of 13 CO that we call MCs may not correspond to an individual objects with well defined boundaries.…”

The effects of ionization feedback on star formation: a case study of the M 16 H II region

“…From component 1 to component 3, we find that several pillars, revealed by their 13 CO J=1-0 emission, are distributed over the edges of the entire M16 region. The northeastern part of the large-scale filament may be disrupted into some small IRDCs because of the expansion of the M16 H II region, which is similar to the case of the filamentary IRDC G34.43+0.24 (Xu et al 2016 Moreover, to investigate the dynamic structure of the molecular gas surrounding the N19 bubble, we made a positionvelocity (PV) diagram along the northwestern direction towards the NGC6611 cluster. The cutting direction goes through N19.…”