scholarly journals Star cluster formation in Orion A

2020 ◽  
Author(s):  
Wanggi Lim ◽  
Fumitaka Nakamura ◽  
Benjamin Wu ◽  
Thomas G Bisbas ◽  
Jonathan C Tan ◽  
...  
Keyword(s):  
Cluster Formation ◽  
Star Cluster ◽  
The Other ◽  
Young Stellar Objects ◽  
Molecular Gas ◽  
Archival Data ◽  
Formation Processes ◽  
Collision Process ◽  
Stellar Objects ◽  
Collision Model

Abstract We introduce new analysis methods for studying the star cluster formation processes in Orion A, especially examining the scenario of a cloud–cloud collision. We utilize the CARMA–NRO Orion survey 13CO (1–0) data to compare molecular gas to the properties of young stellar objects from the SDSS III IN-SYNC survey. We show that the increase of $v_{\rm {}^{13}CO} - v_{\rm YSO}$ and Σ scatter of older YSOs can be signals of cloud–cloud collision. SOFIA-upGREAT 158 μm [C ii] archival data toward the northern part of Orion A are also compared to the 13CO data to test whether the position and velocity offsets between the emission from these two transitions resemble those predicted by a cloud–cloud collision model. We find that the northern part of Orion A, including regions ONC-OMC-1, OMC-2, OMC-3, and OMC-4, shows qualitative agreements with the cloud–cloud collision scenario, while in one of the southern regions, NGC 1999, there is no indication of such a process in causing the birth of new stars. On the other hand, another southern cluster, L 1641 N, shows slight tendencies of cloud–cloud collision. Overall, our results support the cloud–cloud collision process as being an important mechanism for star cluster formation in Orion A.

scholarly journals Aperture Synthesis Observations of CS, NH3, and Continuum in the Bipolar Flow Source NGC2071-IRS

1989 ◽  
Vol 120 ◽  
pp. 254-259
Author(s):  
R. Kawabe ◽  
M. Kitamura ◽  
M. Ishiguro ◽  
T. Hasegawa ◽  
Y. Chikada ◽  
...  
Keyword(s):  
Binary System ◽  
Uv Radiation ◽  
Aperture Synthesis ◽  
The Other ◽  
Central Hole ◽  
Young Stellar Objects ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Stellar Objects ◽  
Disk Structure

ABSTRACT.We have made aperture synthesis observations of CS(J=l-0, 2-1) and NH3(1,1) lines and 49, 98, and 110 GHz continuum in NGC2071-1RS with the Nobeyama Millimeter Array. Wfe have obtained maps of these lines and continuum maps with 2”. 7-20” resolution, ffe have found that dense molecular gas has a disk structure with a radial scale ranging 0.01 pc - 0.1 pc and has a ring-like structure with expanding motion at the central 5000 AU region. We also have found that there exists double dust continuum sources which are separated by 2500 AU in projection and are apparently located at the inner edges of the ring. Our observational results suggest that the disk of molecular gas has a central hole formed by wind and UV radiation from a central young stellar object, the central part is expanding, and that dust continuum emission comes from tangential parts of the shock compressed ring (r~1300 AU, M(H2)~ 21-34 Mo, and n(H2)~ 109) at the most inner side of the disk structure. The other possible model of the dust continuum sources is a binary system of self-luminous young stellar objects.

scholarly journals Large-scale star formation in Auriga region

2019 ◽  
Vol 492 (2) ◽  
pp. 2446-2467 ◽  
Author(s):  
A K Pandey ◽  
Saurabh Sharma ◽  
N Kobayashi ◽  
Y Sarugaku ◽  
K Ogura
Keyword(s):  
Star Formation ◽  
Spanning Tree ◽  
Large Scale ◽  
Minimum Spanning Tree ◽  
Young Stellar Objects ◽  
Molecular Gas ◽  
Archival Data ◽  
Stellar Objects ◽  
Tree Analysis ◽  
Formation Efficiency

ABSTRACT New observations in the VI bands along with archival data from the 2MASS and WISE surveys have been used to generate a catalogue of young stellar objects (YSOs) covering an area of about 6° × 6° in the Auriga region centred at l ∼ 173° and b ∼ 1.5°. The nature of the identified YSOs and their spatial distribution are used to study the star formation in the region. The distribution of YSOs along with that of the ionized and molecular gas reveals two ring-like structures stretching over an area of a few degrees each in extent. We name these structures as Auriga Bubbles 1 and 2. The centre of the Bubbles appears to be above the Galactic mid-plane. The majority of Class I YSOs are associated with the Bubbles, whereas the relatively older population, i.e. Class ii objects are rather randomly distributed. Using the minimum spanning tree analysis, we found 26 probable subclusters having five or more members. The subclusters are between ∼0.5 and ∼3 pc in size and are somewhat elongated. The star formation efficiency in most of the subcluster region varies between 5 ${{\ \rm per\ cent}}$ and 20 ${{\ \rm per\ cent}}$ indicating that the subclusters could be bound regions. The radii of these subclusters also support it.

scholarly journals Bipolar Outflows and Stellar Jets

1987 ◽  
Vol 115 ◽  
pp. 213-237 ◽  
Author(s):  
Ronald L. Snell
Keyword(s):  
Physical Properties ◽  
High Velocity ◽  
Molecular Clouds ◽  
Early Stage ◽  
Young Stellar Objects ◽  
Molecular Gas ◽  
Bipolar Outflows ◽  
Stellar Objects ◽  
Stellar Jets ◽  
Almost All

A wealth of data is now available on the energetic mass outflows that are associated with young stellar objects. This phenomenon is thought to occur at a very early stage in the evolution of stars of almost all masses. The discovery of this energetic event was first made through observations of the rapidly expanding molecular gas that surrounds many of these young stellar objects. A review of the physical properties, including the energetics and morphology, of the expanding molecular gas is presented in this paper. In addition, the role these energetic winds play in affecting the dynamics of the parental molecular clouds is also discussed. Finally, the results of detailed studies of the structure and kinematics of the high velocity molecular gas are reviewed and the evidence for existance of wind-swept cavities and molecular shells within the clouds are presented.

scholarly journals Bipolar H II regions

2018 ◽  
Vol 617 ◽  
pp. A67 ◽  
Author(s):  
M. R. Samal ◽  
L. Deharveng ◽  
A. Zavagno ◽  
L. D. Anderson ◽  
S. Molinari ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Galactic Plane ◽  
Three Dimensional ◽  
Young Stellar Objects ◽  
Formation Processes ◽  
Two Dimensional ◽  
Stellar Objects ◽  
Flat Structures ◽  
Exciting Star

Aims. We aim to identify bipolar Galactic H II regions and to understand their parental cloud structures, morphologies, evolution, and impact on the formation of new generations of stars. Methods. We use the Spitzer-GLIMPSE, Spitzer-MIPSGAL, and Herschel-Hi-GAL surveys to identify bipolar H II regions and to examine their morphologies. We search for their exciting star(s) using NIR data from the 2MASS, UKIDSS, and VISTA surveys. Massive molecular clumps are detected near these bipolar nebulae, and we estimate their temperatures, column densities, masses, and densities. We locate Class 0/I young stellar objects (YSOs) in their vicinities using the Spitzer and Herschel-PACS emission. Results. Numerical simulations suggest bipolar H II regions form and evolve in a two-dimensional flat- or sheet-like molecular cloud. We identified 16 bipolar nebulae in a zone of the Galactic plane between ℓ ± 60° and |b| < 1°. This small number, when compared with the 1377 bubble H II regions in the same area, suggests that most H II regions form and evolve in a three-dimensional medium. We present the catalogue of the 16 bipolar nebulae and a detailed investigation for six of these. Our results suggest that these regions formed in dense and flat structures that contain filaments. We find that bipolar H II regions have massive clumps in their surroundings. The most compact and massive clumps are always located at the waist of the bipolar nebula, adjacent to the ionised gas. These massive clumps are dense, with a mean density in the range of 105 cm−3 to several 106 cm−3 in their centres. Luminous Class 0/I sources of several thousand solar luminosities, many of which have associated maser emission, are embedded inside these clumps. We suggest that most, if not all, massive 0/I YSO formation has probably been triggered by the expansion of the central bipolar nebula, but the processes involved are still unknown. Modelling of such nebula is needed to understand the star formation processes at play.

scholarly journals Star Cluster Formation in Extreme Starburst Environments

2005 ◽  
Vol 13 ◽  
pp. 185-186
Author(s):  
Richard de Grijs
Keyword(s):  
High Pressure ◽  
Star Formation ◽  
High Resolution ◽  
Empirical Evidence ◽  
Hubble Space Telescope ◽  
Cluster Formation ◽  
Dominant Mode ◽  
Star Cluster ◽  
Formation Processes ◽  
Galaxy Interactions

AbstractThe currently available empirical evidence on the star formation processes in the extreme, high-pressure environments induced by galaxy encounters, mostly based on high-resolution Hubble Space Telescope imaging observations, strongly suggests that star cluster formation is an important and perhaps even the dominant mode of star formation in the starburst events associated with galaxy interactions.

scholarly journals High-resolution Infrared Spectroscopy of Hot Molecular Gas in AFGL 2591 and AFGL 2136: Accretion in the Inner Regions of Disks around Massive Young Stellar Objects

2020 ◽  
Vol 900 (2) ◽  
pp. 104
Author(s):  
Andrew G. Barr ◽  
Adwin Boogert ◽  
Curtis N. DeWitt ◽  
Edward Montiel ◽  
Matthew J. Richter ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
High Resolution ◽  
Young Stellar Objects ◽  
Molecular Gas ◽  
Stellar Objects

scholarly journals Turbulent Mixing Layers in Herbig-Haro and Embedded H2 Jets

1997 ◽  
Vol 182 ◽  
pp. 103-110 ◽  
Author(s):  
Alberto Noriega-Crespo
Keyword(s):  
Turbulent Mixing ◽  
Near Infrared ◽  
Surrounding Medium ◽  
Mixing Layers ◽  
Young Stellar Objects ◽  
Molecular Gas ◽  
Stellar Objects ◽  
Turbulent Entrainment ◽  
Millimeter Wavelengths

Outflows arising from young stellar objects interact with their surrounding medium through different mechanisms, such as shocks, turbulence and /or entrainment. These two last mechanisms have recently begun to be fully developed in an effort to understand the coupling of the stellar jet gas (mostly atomic) with the molecular environment. Observationally a number of objects are being studied in the near infrared and millimeter wavelengths to map the warm (H2) and cold (CO) molecular gas, respectively. In this paper we discuss some of the properties in the near infrared of various embedded jets in the context of turbulent entrainment.

scholarly journals Molecular gas and triggered star formation surrounding Wolf-Rayet stars

2012 ◽  
Vol 8 (S292) ◽  
pp. 48-48
Author(s):  
Tie Liu ◽  
Yuefang Wu ◽  
Huawei Zhang
Keyword(s):  
Star Formation ◽  
Stellar Wind ◽  
Young Stellar Objects ◽  
Molecular Gas ◽  
Number Density ◽  
Stellar Objects ◽  
Molecular Emission ◽  
Wind Velocities ◽  
Expanding Shells

AbstractThe environments surrounding nine Wolf-Rayet stars were studied in molecular emission. Expanding shells were detected surrounding these WR stars (see left panels of Figure 1). The average masses and radii of the molecular cores surrounding these WR stars anti-correlate with the WR stellar wind velocities (middle panels of Figure 1), indicating the WR stars has great impact on their environments. The number density of Young Stellar Objects (YSOs) is enhanced in the molecular shells at ∼5 arcmin from the central WR star (lower-right panel of Figure 1). Through detailed studies of the molecular shells and YSOs, we find strong evidences of triggered star formation in the fragmented molecular shells (Liu et al. 2010).

scholarly journals G133.50+9.01: a likely cloud–cloud collision complex triggering the formation of filaments, cores, and a stellar cluster

2020 ◽  
Vol 499 (3) ◽  
pp. 3620-3629
Author(s):  
Namitha Issac ◽  
Anandmayee Tej ◽  
Tie Liu ◽  
Yuefang Wu
Keyword(s):  
Cluster Formation ◽  
Observational Evidence ◽  
Young Stellar Objects ◽  
Molecular Line ◽  
Stellar Objects ◽  
Stellar Cluster ◽  
Dense Cores ◽  
Bolometer Array ◽  
Bona Fide ◽  
Common User

ABSTRACT We present compelling observational evidence of G133.50+9.01 being a bona fide cloud–cloud collision candidate with signatures of induced filament, core, and cluster formation. The CO molecular line observations reveal that the G133.50+9.01 complex is made of two colliding molecular clouds with systemic velocities, $\rm -16.9$ and $\rm -14.1\, km\, s^{-1}$. The intersection of the clouds is characterized by broad bridging features characteristic of collision. The morphology of the shocked layer at the interaction front resembles an arc-like structure with enhanced excitation temperature and H2 column density. A complex network of filaments is detected in the Submillimeter Common-User Bolometer Array 2 850 $\rm \mu m$ image with 14 embedded dense cores, all well correlated spatially with the shocked layer. A stellar cluster revealed through an overdensity of identified Classes I and II young stellar objects is found located along the arc in the intersection region corroborating with a likely collision induced origin.

scholarly journals On the structure and kinematics of molecular clouds from large scale mapping of mm-lines

1991 ◽  
Vol 147 ◽  
pp. 11-20
Author(s):  
J. Bally ◽  
W. D. Langer ◽  
R. W. Wilson ◽  
A. A. Stark ◽  
M. W. Pound
Keyword(s):  
Molecular Clouds ◽  
Large Scale ◽  
Massive Stars ◽  
Vital Role ◽  
Solar Neighborhood ◽  
Young Stellar Objects ◽  
Small Scale ◽  
Molecular Gas ◽  
Main Body ◽  
Stellar Objects

Molecular gas in the interior of the Orion superbubble consists of sheets, filaments, and partial shells in which the active star forming dense cloud cores are embedded. The main body of the Orion A and B clouds and at least 14 smaller clouds in Orion region are cometary in appearance suggesting strong interaction with massive stars in the Orion OB association. While the small scale (< 1 pc) structure of the clouds may be determined primarily by internal magnetic fields, gravity, and the effects of outflows from young stellar objects, the large scale morphology and kinematics is affected by the energy injected by massive stars. Supernovae, stellar winds, and radiation have compressed, accelerated, ablated, and dispersed molecular gas over the last 107 years. Most GMC/OB star complexes in the Solar neighborhood exhibit morphological and kinematic properties similar to the Orion region. We argue that energy injection by massive stars plays a vital role in the evolution of the ISM and may be responsible for much of the observed large-scale structure and kinematics of molecular clouds.

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