scholarly journals SiO emission as a probe of cloud–cloud collisions in infrared dark clouds

2020 ◽  
Vol 499 (2) ◽  
pp. 1666-1681
Author(s):  
G Cosentino ◽  
I Jiménez-Serra ◽  
J D Henshaw ◽  
P Caselli ◽  
S Viti ◽  
...  
Keyword(s):  
Star Formation ◽  
Initial Conditions ◽  
Cluster Formation ◽  
Silicon Monoxide ◽  
High Sensitivity ◽  
H Ii Regions ◽  
Line Profiles ◽  
Stellar Cluster ◽  
Dark Clouds ◽  
Infrared Dark Clouds

ABSTRACT Infrared dark clouds (IRDCs) are very dense and highly extincted regions that host the initial conditions of star and stellar cluster formation. It is crucial to study the kinematics and molecular content of IRDCs to test their formation mechanism and ultimately characterize these initial conditions. We have obtained high-sensitivity Silicon Monoxide, SiO(2–1), emission maps towards the six IRDCs, G018.82–00.28, G019.27+00.07, G028.53–00.25, G028.67+00.13, G038.95–00.47, and G053.11+00.05 (cloud A, B, D, E, I, and J, respectively), using the 30-m antenna at the Instituto de Radioastronomía Millimétrica (IRAM30m). We have investigated the SiO spatial distribution and kinematic structure across the six clouds to look for signatures of cloud–cloud collision events that may have formed the IRDCs and triggered star formation within them. Towards clouds A, B, D, I, and J, we detect spatially compact SiO emission with broad-line profiles that are spatially coincident with massive cores. Towards the IRDCs A and I, we report an additional SiO component that shows narrow-line profiles and that is widespread across quiescent regions. Finally, we do not detect any significant SiO emission towards cloud E. We suggest that the broad and compact SiO emission detected towards the clouds is likely associated with ongoing star formation activity within the IRDCs. However, the additional narrow and widespread SiO emission detected towards cloud A and I may have originated from the collision between the IRDCs and flows of molecular gas pushed towards the clouds by nearby H ii regions.

SiO as a chemical signature of outflows from bright, compact sources in MSX IR-dark clouds

2004 ◽  
Vol 82 (6) ◽  
pp. 740-743 ◽  
Author(s):  
P A Feldman ◽  
R O Redman ◽  
L W Avery ◽  
J Di Francesco ◽  
J D Fiege ◽  
...  
Keyword(s):  
Star Formation ◽  
Young Stellar Objects ◽  
Line Profiles ◽  
Bipolar Outflows ◽  
Dark Cloud ◽  
Stellar Objects ◽  
Dark Clouds ◽  
Dense Cores ◽  
Infrared Dark Clouds ◽  
Compact Sources

The line profiles of dense cores in infrared-dark clouds indicate the presence of young stellar objects (YSOs), but the youth of the YSOs and the large distances to the clouds make it difficult to distinguish the outflows that normally accompany star formation from turbulence within the cloud. We report here the first unambiguous identification of a bipolar outflow from a young stellar object (YSO) in an infrared-dark cloud, using observations of SiO to distinguish the relatively small amounts of gas in the outflow from the rest of the ambient cloud. Key words: infrared-dark clouds, star formation, bipolar outflows, SiO, G81.56+0.10.

scholarly journals Fire from Ice - Massive Star Birth from Infrared Dark Clouds

2017 ◽  
Vol 13 (S332) ◽  
pp. 139-152
Author(s):  
Jonathan C. Tan
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Initial Conditions ◽  
Massive Star Formation ◽  
Dark Clouds ◽  
Complex Process ◽  
Infrared Dark Clouds

AbstractI review massive star formation in our Galaxy, focussing on initial conditions in Infrared Dark Clouds (IRDCs), including the search for massive pre-stellar cores (PSCs), and modeling of later stages of massive protostars, i.e., hot molecular cores (HMCs). I highlight how developments in astrochemistry, coupled with rapidly improving theoretical/computational and observational capabilities are helping to improve our understanding of the complex process of massive star formation.

scholarly journals A New Comprehensive Catalogue of Infrared Dark Clouds

2009 ◽  
Vol 5 (H15) ◽  
pp. 796-796
Author(s):  
G. A. Fuller ◽  
N. Peretto
Keyword(s):  
Star Formation ◽  
Initial Conditions ◽  
Future Studies ◽  
Dark Clouds ◽  
Star Formation Activity ◽  
Extraction Algorithm ◽  
The Galaxy ◽  
The Individual ◽  
Density Image ◽  
Infrared Dark Clouds

AbstractTo better characterise infrared dark clouds (IRDCs), and the star formation within them, a comprehensive catalogue of IRDCs has been constructed from the Spitzer GLIMPSE and MIPSGAL archival data. Mosaicing the individual survey blocks together, we have used a new extraction method to identify dark clouds up to 30′ in size, and produce a column density image of each cloud. In total the catalogue contains over 11,000 clouds, defined as connected regions with 8 micron optical depth > 0.35 (corresponding to column densities < 1022 cm−2). The extraction algorithm also identifies sub-structures (fragments) within each cloud. These Spitzer dark clouds (SDCs) range in mass from 10M⊙ to 104M⊙. About 80% of the SDCs were previously unidentified. Only ~ 30% of the SDCs are associated with 24μm point-like sources, leaving the majority of these clouds with no apparent sign of star formation activity. This new catalogue provides an important new resource for future studies of the initial conditions of star formation in the Galaxy.

scholarly journals Observational Studies of Pre-Stellar Cores and Infrared Dark Clouds

2011 ◽  
Vol 7 (S280) ◽  
pp. 19-32 ◽  
Author(s):  
Paola Caselli
Keyword(s):  
Molecular Cloud ◽  
Chemical Structure ◽  
Initial Conditions ◽  
Theoretical Work ◽  
High Mass ◽  
Mass Star ◽  
Stellar Cluster ◽  
Dark Clouds ◽  
Low Mass ◽  
Infrared Dark Clouds

AbstractStars like our Sun and planets like our Earth form in dense regions within interstellar molecular clouds, called pre-stellar cores (PSCs). PSCs provide the initial conditions in the process of star and planet formation. In the past 15 years, detailed observations of (low-mass) PSCs in nearby molecular cloud complexes have allowed us to find that they are cold (T < 10K) and quiescent (molecular line widths are close to thermal), with a chemistry profoundly affected by molecular freeze-out onto dust grains. In these conditions, deuterated molecules flourish, becoming the best tools to unveil the PSC physical and chemical structure. Despite their apparent simplicity, PSCs still offer puzzles to solve and they are far from being completely understood. For example, what is happening to the gas and dust in their nuclei (the future stellar cradles) is still a mystery that awaits for ALMA. Other important questions are: how do different environments and external conditions affect the PSC physical/chemical structure? Are PSCs in high-mass star forming regions similar to the well-known low-mass PSCs? Here I review observational and theoretical work on PSCs in nearby molecular cloud complexes and the ongoing search and study of massive PSCs embedded in infrared dark clouds (IRDCs), which host the initial conditions for stellar cluster and high-mass star formation.

scholarly journals Molecular Line Observations of Infrared Dark Clouds: Seeking the Precursors to Intermediate and Massive Star Formation

2006 ◽  
Vol 166 (2) ◽  
pp. 567-584 ◽  
Author(s):  
S. E. Ragan ◽  
E. A. Bergin ◽  
R. Plume ◽  
D. L. Gibson ◽  
D. J. Wilner ◽  
...  
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Star Formation ◽  
Molecular Line ◽  
Dark Clouds ◽  
Infrared Dark Clouds

scholarly journals Scale Free Processes in Stellar Cluster Formation

2015 ◽  
Vol 11 (A29B) ◽  
pp. 717-718
Author(s):  
Nate Bastian
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Cluster Formation ◽  
Formation Rate ◽  
Stellar Clusters ◽  
Host Galaxies ◽  
Stellar Cluster ◽  
Scale Free ◽  
Model Predictions ◽  
The Common

AbstractWe review some of the basic population properties of stellar clusters, as well as how they relate to star-formation more broadly within their host galaxies. Despite the common assertion, the vast majority of stars do not form within stellar clusters. For typical galaxies (including the solar neighbourhood), the fraction of stars forming in clusters is ~10%. There are indications however that this fraction increases as a function of increasing star-formation rate surface density, in agreement with model predictions (based on a turbulent ISM and relatively straight-forward prescriptions of star-formation).

scholarly journals Massive and low-mass protostars in massive “starless” cores

2019 ◽  
Vol 622 ◽  
pp. A54 ◽  
Author(s):  
Thushara Pillai ◽  
Jens Kauffmann ◽  
Qizhou Zhang ◽  
Patricio Sanhueza ◽  
Silvia Leurini ◽  
...  
Keyword(s):  
Star Formation ◽  
Detection Limit ◽  
High Mass ◽  
Mass Star ◽  
Core Mass ◽  
Filamentary Structure ◽  
Dark Clouds ◽  
Low Mass ◽  
Infrared Dark Clouds ◽  
Dense Clump

The infrared dark clouds (IRDCs) G11.11−0.12 and G28.34+0.06 are two of the best-studied IRDCs in our Galaxy. These two clouds host clumps at different stages of evolution, including a massive dense clump in both clouds that is dark even at 70 and 100 μm. Such seemingly quiescent massive dense clumps have been speculated to harbor cores that are precursors of high-mass stars and clusters. We observed these two “prestellar” regions at 1 mm with the Submillimeter Array (SMA) with the aim of characterizing the nature of such cores. We show that the clumps fragment into several low- to high-mass cores within the filamentary structure of the enveloping cloud. However, while the overall physical properties of the clump may indicate a starless phase, we find that both regions host multiple outflows. The most massive core though 70 μm dark in both clumps is clearly associated with compact outflows. Such low-luminosity, massive cores are potentially the earliest stage in the evolution of a massive protostar. We also identify several outflow features distributed in the large environment around the most massive core. We infer that these outflows are being powered by young, low-mass protostars whose core mass is below our detection limit. These findings suggest that low-mass protostars have already formed or are coevally formed at the earliest phase of high-mass star formation.

scholarly journals Cold Dark Clouds: The Initial Conditions for Star Formation

2007 ◽  
Vol 45 (1) ◽  
pp. 339-396 ◽  
Author(s):  
Edwin A. Bergin ◽  
Mario Tafalla
Keyword(s):  
Star Formation ◽  
Initial Conditions ◽  
Dark Clouds

scholarly journals Probing the initial conditions of high-mass star formation

2019 ◽  
Vol 627 ◽  
pp. A85 ◽  
Author(s):  
Chuan-Peng Zhang ◽  
Timea Csengeri ◽  
Friedrich Wyrowski ◽  
Guang-Xing Li ◽  
Thushara Pillai ◽  
...  
Keyword(s):  
Star Formation ◽  
Multiple Scales ◽  
Initial Conditions ◽  
Dust Emission ◽  
Radio Continuum ◽  
High Mass ◽  
Small Scale ◽  
High Angular Resolution ◽  
H Ii Regions ◽  
Mass Star

Context. Fragmentation and feedback are two important processes during the early phases of star formation. Aims. Massive clumps tend to fragment into clusters of cores and condensations, some of which form high-mass stars. In this work, we study the structure of massive clumps at different scales, analyze the fragmentation process, and investigate the possibility that star formation is triggered by nearby H ii regions. Methods. We present a high angular resolution study of a sample of massive proto-cluster clumps G18.17, G18.21, G23.97N, G23.98, G23.44, G23.97S, G25.38, and G25.71. Combining infrared data at 4.5, 8.0, 24, and 70 μm, we use a few arcsecond resolution, radiometer and millimeter inteferometric data taken at 1.3 cm, 3.5 mm, 1.3 mm, and 870 μm to study their fragmentation and evolution. Our sample is unique in the sense that all the clumps have neighboring H ii regions. Taking advantage of that, we tested triggered star formation using a novel method where we study the alignment of the center of mass traced by dust emission at multiple scales. Results. The eight massive clumps, identified based on single-dish observations, have masses ranging from 228 to 2279 M⊙ within an effective radius of Reff ~ 0.5 pc. We detect compact structures towards six out of the eight clumps. The brightest compact structures within infrared bright clumps are typically associated with embedded compact radio continuum sources. The smaller scale structures of Reff ~ 0.02 pc observed within each clump are mostly gravitationally bound and massive enough to form at least a B3-B0 type star. Many condensations have masses larger than 8 M⊙ at a small scale of Reff ~ 0.02 pc. We find that the two infrared quiet clumps with the lowest mass and lowest surface density with <300 M⊙ do not host any compact sources, calling into question their ability to form high-mass stars. Although the clumps are mostly infrared quiet, the dynamical movements are active at clump scale (~1 pc). Conclusions. We studied the spatial distribution of the gas conditions detected at different scales. For some sources we find hints of external triggering, whereas for others we find no significant pattern that indicates triggering is dynamically unimportant. This probably indicates that the different clumps go through different evolutionary paths. In this respect, studies with larger samples are highly desired.

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