Searching for shocks in high-mass starless clump candidates

Abstract

In order to search for shocks in the very early stage of star formation, we performed single-point surveys of SiO J=1-0, 2-1 and 3-2 lines and the H${}_2$CO $2_{12}-1_{11}$ line toward a sample of 100 high-mass starless clump candidates (SCCs) by using the Korean VLBI Network (KVN) 21-m radio telescopes. The detection rates of the SiO J=1-0, 2-1, 3-2 lines and the H${}_2$CO line are $31.0\%$, $31.0\%$, $19.5\%$ and $93.0\%$, respectively. Shocks seem to be common in this stage of massive star formation. The widths of the observed SiO lines (full width at zero power (FWZP)) range from 3.4 to 55.1 km s${}^{-1}$. A significant fraction ($\sim 29\%$) of the detected SiO spectra have broad line widths (FWZP $>20km{s}^{-1}$), which are very likely associated with fast shocks driven by protostellar outflows. This result suggests that about one third of the SiO-detected SCCs are not really starless but protostellar. On the other hand, about 40$\%$ of the detected SiO spectra show narrow line widths (FWZP<10 $km{s}^{-1}$) probably associated with low-velocity shocks which are not necessarily protostellar in origin. The estimated SiO column densities are mostly $0.31-4.32\times 10^{12}c{m}^{-2}$. Comparing the SiO column densities derived from SiO J=1-0 and 2-1 lines, we suggest that the SiO molecules in the SCCs may be in the non-LTE condition. The SiO abundances to H${}_2$ are usually $0.20-10.92\times 10^{-10}$.

arXiv comment19 pages, 13 figures

References in corpus (27)

• A computer program for fast non-LTE analysis of interstellar line spectra
• ATLASGAL - The APEX Telescope Large Area Survey of the Galaxy at 870 microns
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• High-Mass Star and Massive Cluster Formation in the Milky Way
• How to Calculate Molecular Column Density
• ATLASGAL --- properties of a complete sample of Galactic clumps
• Structure and Evolution of the Envelopes of Deeply Embedded Massive Young Stars
• Formation of Massive Molecular Cloud Cores by Cloud-cloud Collision
• The Bolocam Galactic Plane Survey IX: Data Release 2 and Outer Galaxy Extension
• Parsec-scale SiO Emission in an Infrared Dark Cloud
• W43: the closest molecular complex of the Galactic Bar?
• Low-velocity shocks traced by extended SiO emission along the W43 ridges: witnessing the formation of young massive clusters
• The Bolocam Galactic Plane Survey. XIV. Physical Properties of Massive Starless and Star Forming Clumps
• ATLASGAL-selected massive clumps in the inner Galaxy, II: Characterisation of different evolutionary stages and their SiO emission
• Distinct Chemical Regions in the "Prestellar" Infrared Dark Cloud (IRDC) G028.23-00.19
• Outflow and dense gas emission from massive Infrared Dark Clouds
• ALMA observations of fragmentation, sub-structure, and protostars in high-mass starless clump candidates
• SiO emission from low- and high-velocity shocks in Cygnus-X massive dense clumps
• Tracing extended low-velocity shocks through SiO emission - Case study of the W43-MM1 ridge
• The Bolocam Galactic Plane Survey. XII. Distance Catalog Expansion Using Kinematic Isolation of Dense Molecular Cloud Structures With 13CO(1-0)
• A SiO J = 5 - 4 Survey Toward Massive Star Formation Regions
• Kinetic temperature of massive star forming molecular clumps measured with formaldehyde. II. The Large Magellanic Cloud
• SiO excitation from dense shocks in the earliest stages of massive star formation
• Widespread SiO and CH3OH emission in Filamentary Infrared Dark Clouds
• Searching for Inflow Towards Massive Starless Clump Candidates Identified in the Bolocam Galactic Plane Survey
• Molecular Gas Density Measured with H${}_2$CO and CS toward a Spiral Arm of M51
• Accretion and Feedback in Star Cluster Formation

Cited by in corpus (8)

• Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde IV. The ALMA view of N113 and N159W in the LMC
• A global view on star formation: The GLOSTAR Galactic plane survey VIII. Formaldehyde absorption in Cygnus~X
• A survey of SiO $J=$ 1 -- 0 emission toward massive star-forming regions
• SiO Outflows in the Most Luminous and Massive Protostellar Sources of the Southern Sky
• Star Formation in Extreme Environments: A 200 pc High Velocity Gas Stream in the Galactic Centre
• Spatial distributions and kinematics of shocked and ionized gas in M17
• Different molecular filament widths as tracers of accretion onto filaments
• Origins of the shocks in high-mass starless clump candidates