scholarly journals Studies of star formation in isolated small dark clouds – I. A catalogue of southern Bok globules: optical and IRAS properties

1995 ◽  
Keyword(s):  
Star Formation ◽  
Dark Clouds ◽  
Bok Globules

scholarly journals Triggered star formation in the isolated cluster CB 34?

2006 ◽  
Vol 2 (S237) ◽  
pp. 464-464
Author(s):  
Dawn E. Peterson ◽  
R. A. Gutermuth ◽  
M. F. Skrutskie ◽  
S. T. Megeath ◽  
J. L. Pipher ◽  
...  
Keyword(s):  
Star Formation ◽  
Class Ii ◽  
High Rate ◽  
Young Stellar Objects ◽  
Collapse Mechanism ◽  
Stellar Objects ◽  
Hii Region ◽  
Dark Clouds ◽  
Sky Survey ◽  
Bok Globules

AbstractBok globules, optically opaque small dark clouds, are classical examples of isolated star formation. However, the collapse mechanism for these cold, dense clouds of gas and dust is not well understood. Observations of Bok globules include some which appear to be starless while others harbor single stars, binaries and even small groups of forming stars. One example of a Bok globule forming a group of stars is CB 34, observed with both the IRAC and MIPS instruments as part of the Spitzer Young Cluster Survey. Based on initial analysis of 1-8 μm photometry from IRAC and the Two Micron All Sky Survey (2MASS), we identified 9 Class 0/I and 14 Class II young stellar objects within the small, 4.5′ × 4.5′ region encompassing CB 34. This unusually high number of protostars compared with Class II sources is intriguing because it implies a high rate of star formation. Therefore we have begun a larger study of this region in order to determine why and how CB 34 started forming stars at such a high rate. Is CB 34 embedded within a larger HII region which may have triggered its collapse or does it appear to have collapsed in isolation from outside influences?

scholarly journals Evidence for collapse in dark clouds

1997 ◽  
Vol 178 ◽  
pp. 193-202
Author(s):  
S. Zhou
Keyword(s):  
Star Formation ◽  
Dark Cloud ◽  
Dark Clouds ◽  
Bok Globules ◽  
Cloud Cores

Bart Bok speculated back in the 1940's that dark cloud cores (i.e. Bok globules) are sites of star formation. The means for probing the dark cloud cores, molecules, were not discovered until much later. Today, we can finally say Bart Bok was right! Evidence for collapse in dark cloud cores will be discussed in general, along with specific examples of collapse candidates. We also describe methods to search for new candidates and the complications in identifying the infall motion.

scholarly journals Star Formation in the Galaxy

1992 ◽  
Vol 45 (4) ◽  
pp. 411
Author(s):  
Peter J McGregor
Keyword(s):  
Star Formation ◽  
Spatial Scales ◽  
Mass Star ◽  
Dark Cloud ◽  
Single Star ◽  
Dark Clouds ◽  
Collapse Models ◽  
The Galaxy ◽  
Low Mass ◽  
Bok Globules

Star formation in the Galaxy occurs on different spatial scales from single star formation events in Bok Globules to the formation of OB associations and star clusters. We review recent observations of Bok Globules and relate them to the dense NH3 cores observed in dark clouds. Recent work on the Chamaeleon I dark cloud supports quasi-static subcritical collapse models for low mass star formation. This cloud is a typical region of low mass star formation similar to the Taurus-Auriga clouds; star formation has continued in the cloud for ",107 yr, the most massive embedded stars have masses of "'2M0, and the cloud appears to be magnetically supported in its long dimension.

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 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

Star Formation in Southern Bok Globules

1997 ◽  
pp. 405-408
Author(s):  
K. Kämpgen ◽  
R. Chini ◽  
M. Nielbock ◽  
M. Albrecht
Keyword(s):  
Star Formation ◽  
Bok Globules

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 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.

High-resolution interstellar spectroscopy and star formation

1981 ◽  
Vol 303 (1480) ◽  
pp. 565-579 ◽  
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Molecular Spectroscopy ◽  
Active Regions ◽  
Infrared Source ◽  
Very Large Array ◽  
Dark Clouds ◽  
The Past ◽  
Different Types ◽  
Interstellar Molecular Clouds

During the past several years, high spatial and spectral resolution molecular spectroscopy has greatly contributed to our knowledge of the physics, dynamics and chemistry of interstellar molecular clouds and thus has led to a better understanding of the conditions that lead to star formation. According to their physical properties, molecular clouds can be grouped into four different types: (i) the dark clouds, (ii) the molecular clouds associated with H+ regions, (iii) the ‘protostellar’ (or maser) environment, and (iv) the molecular envelopes of late-type stars. The first three types of cloud contain generally active regions of star formation. As typical examples the properties are discussed of individual clouds such as TMC 1 and L 183 for the cold clouds, S 140 and S 106 for the warm dark clouds with embedded infrared source, and Orion A for a region with associated H+ region. In S 140, NH 3 is clumped on a scale of not more than 20", whereas recent observations towards Orion A with the Very Large Array show that NH 3 clumps on a scale smaller than 5".

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