scholarly journals Interaction between molecular outflows and dense gas in the cluster-forming region OMC-2/FIR4

2006 ◽  
Vol 2 (S237) ◽  
pp. 475-475
Author(s):  
Yoshito Shimajiri ◽  
S. Takahashi ◽  
S. Takakuwa ◽  
M. Saito ◽  
R. Kawabe
Keyword(s):  
Cluster Formation ◽  
Major Axis ◽  
List Type ◽  
Dense Gas ◽  
Continuum Source ◽  
Molecular Outflows ◽  
Molecular Outflow ◽  
Dense Cores ◽  
Potential Source ◽  
Molecular Lines

AbstractSince most stars are born as members of clusters (Lada & Lada 2003), it is important to clarified the detailed mechanism of cluster formation for comprehensive understanding of star formation. However, our current understanding of cluster formation is limited due to the followings; (a)Cluster forming regions are located at the far distance.(b)There are complex mixtures of outflows and dense gas in cluster forming regions. So, we focused on the Orion Molecular Cloud 2 region (OMC-2), a famous cluster-forming region (Lada & Lada 2003) and the most nearest GMC. We observed the FIR 4 region with the Nobeyama Millimeter Array(NMA), Atacama Submillimeter Telescope Experiment (ASTE). In this region, there are 3 protostars (FIR3, FIR4, FIR5) which were identified as 1.3 mm dust continuum sources (Chini et al. 1997) and driving sources of mixed outflows, and FIR 4 is the most strongest source of 1.3 mm dust continuum in OMC-2. Molecular lines we adopted are a high density (105cm−3) gas tracer of H13CO+ (J=1-0), a molecular outflow tracer of 12CO(J=1-0) and 12CO(J=3-2), and SiO(J=2-1 v=0) as a tracer of shocks associated with an interaction between outflows and dense gas.From results of the 12CO(J=1-0) outflow, H13CO+ dense gas, and the SiO shock, the outflow from FIR 3 interacts with dense gas in the FIR 4 region. Moreover the Position-Velocity diagram along the major axis of the 12CO(J=3-2) outflow shows that the 12CO(J=1-0) and SiO emission exhibits a L shape (the line widths increase in the interacting region in morphology). This is an evidence of interaction between the outflows and dense gas (Takakuwa et al. 2003). From result of the 3 mm dust continuum, the interacted region by the molecular outflow of FIR 3 is an assemble of seven dense cores. The mass of each core is 0.1-0.8 M. This clumpy structure is evident only at FIR 4 in the entire OMC-2/3 region. There are possible that two cores are in the proto-stellar phase, because 3 mm dust continuum source correspond to NIR source or 3.6 cm f-f jet source. From these results, cores in the FIR 4 region may be potential source of the next-generation stars. In the other words, there is a possibility that the molecular outflow ejected from FIR 3 is triggering the cluster formation in the FIR 4 region.

scholarly journals Shock Chemistry in Bipolar Molecular Outflows

1997 ◽  
Vol 182 ◽  
pp. 153-162 ◽  
Author(s):  
R. Bachiller ◽  
M. Pérez Gutiérrez
Keyword(s):  
Chemical Composition ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Molecular Outflows ◽  
Molecular Outflow ◽  
Interstellar Ice ◽  
Chemical Studies ◽  
Molecular Lines

Chemical studies have a great potential to study the structure and evolution of the bipolar molecular outflows driven by young stellar objects. In this paper, we discuss some very recent mm-wave studies of L 1157, a bipolar molecular outflow driven by a Class 0 protostar. These observations are very useful to illustrate the chemical alterations produced by a violent highly-collimated outflow. Different molecular lines are observed to trace different components of the gas. Some molecules are abundant in the quiescent medium but are not observed in the shock (e.g. C3H2, N2H+, H13CO+, DCO+), whereas some otherwise rare molecules are very enhanced at the shocked region (e.g. SiO, CH3OH, H2CO, HCN, CN, SO, SO2). In addition, we have observed strong gradients in the chemical composition across the outflow blue lobe. We briefly discuss the chemistry of the most important molecules, devoting special attention to the species which are thought to be abundant in interstellar ice mantles.

scholarly journals Binary outflows from young stars: interaction of co-orbital jet and wind

2019 ◽  
Author(s):  
Chris J R Lynch ◽  
Michael D Smith ◽  
Simon C O Glover
Keyword(s):  
Young Stars ◽  
Young Stellar Objects ◽  
Molecular Flow ◽  
Stellar Objects ◽  
Star Forming ◽  
Molecular Outflows ◽  
Molecular Outflow ◽  
T Tauri ◽  
Molecular Lines ◽  
Insight Into

Abstract Jets from young stellar objects provide insight into the workings of the beating heart at the centre of star forming cores. In some cases, multiple pulsed outflows are detected such as the atomic and molecular jets from a proposed binary system in the T Tauri star HH 30. We investigate here the development and propagation of duelling atomic and molecular outflows stemming from the two stars in co-orbit. We perform a series of numerical experiments with the ZEUS-MP code with enhanced cooling and chemistry modules. The aim of this work is to identify signatures on scales of order 100 AU. The jet sources are off the grid domain and so it is the propagation and interaction from ∼ 20 AU out to 100 AU simulated here. We find that the molecular flow from the orbiting source significantly disturbs the atomic jet, deflecting and twisting the jet and disrupting the jet knots. Regions of high ionisation are generated as the atomic jet rams through the dense molecular outflow. Synthetic images in atomic and molecular lines are presented which demonstrate identifying signatures. In particular, the structure within the atomic jet is lost and Hα may trace the walls of the present CO cavity or where the walls have been recently. These results provide a framework for the interpretation of upcoming high resolution observations.

scholarly journals Circum-nuclear molecular disks: Role in AGN fueling and feedback

2019 ◽  
Vol 15 (S359) ◽  
pp. 312-317
Author(s):  
Francoise Combes
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
High Resolution ◽  
Large Scale ◽  
Active Galaxy ◽  
Small Scale ◽  
Massive Black Hole ◽  
Molecular Outflows ◽  
Molecular Outflow

AbstractGas fueling AGN (Active Galaxy Nuclei) is now traceable at high-resolution with ALMA (Atacama Large Millimeter Array) and NOEMA (NOrthern Extended Millimeter Array). Dynamical mechanisms are essential to exchange angular momentum and drive the gas to the super-massive black hole. While at 100pc scale, the gas is sometimes stalled in nuclear rings, recent observations reaching 10pc scale (50mas), may bring smoking gun evidence of fueling, within a randomly oriented nuclear gas disk. AGN feedback is also observed, in the form of narrow and collimated molecular outflows, which point towards the radio mode, or entrainment by a radio jet. Precession has been observed in a molecular outflow, indicating the precession of the radio jet. One of the best candidates for precession is the Bardeen-Petterson effect at small scale, which exerts a torque on the accreting material, and produces an extended disk warp. The misalignment between the inner and large-scale disk, enhances the coupling of the AGN feedback, since the jet sweeps a large part of the molecular disk.

scholarly journals Molecular Line Studies of Dense Core Motions

1992 ◽  
Vol 150 ◽  
pp. 217-222
Author(s):  
Yuefang Wu
Keyword(s):  
Line Width ◽  
Dense Core ◽  
Emission Region ◽  
Molecular Line ◽  
Dense Cores ◽  
Chemical Effects ◽  
Size Relationship ◽  
Molecular Lines ◽  
Line Widths

Molecular lines have revealed various supporting motions in dense cores. Line widths and emission region sizes of NH3 and CS in the same kind of cores or of the same line in cores with or without sources are different and can not be explained with the line width- size relationship. Outflows in dense cores show rich characteristics which can account for the NH3 emission difference between the two kinds of the cores; CS emission is consistent with the chemical effects in shocked regions. Rotation exists in both kinds of cores and may be related to the observed polarities and collimations of outflows.

scholarly journals Non thermal sputtering of grains and production of SiO in interstellar shocks

1997 ◽  
Vol 178 ◽  
pp. 113-128 ◽  
Author(s):  
Guillaume Pineau Des Forêts ◽  
David Flower
Keyword(s):  
Gas Phase ◽  
Satisfactory Agreement ◽  
Shock Model ◽  
Dense Gas ◽  
Heavy Particles ◽  
Molecular Outflows ◽  
Dark Clouds ◽  
Interstellar Grains ◽  
Upper Limits ◽  
Interstellar Shocks

We present recent results for the yields of Si and O, produced in the sputtering of SiO2 by ions of different masses, and show the importance of sputtering by heavy particles at low streaming velocities. These data are incorporated in a C-shock model to study the erosion of interstellar grains and the release of silicon through non-thermal sputtering within the shock. Once in the gas phase, the atomic silicon reacts with O2 and is rapidly transformed into SiO. The column densities of SiO thus calculated are compared with the observations of molecular outflows with a satisfactory agreement. In the postshock gas, SiO disappears from the gas phase through the reaction SiO(OH,H)SiO2 and SiO2 remains, unseen, in the cold dense gas. This could explain the extremely low upper limits of SiO deduced from observations of dark clouds.

scholarly journals A large scale survey of dense cores and molecular outflows in Ophiuchus

1991 ◽  
Vol 147 ◽  
pp. 462-463
Author(s):  
Akira Mizuno ◽  
Satonori Nozawa ◽  
Takahiro Iwata ◽  
Yasuo Fukui
Keyword(s):  
High Velocity ◽  
Large Scale ◽  
Mass Density ◽  
Point Sources ◽  
Main Body ◽  
Grid Spacing ◽  
Molecular Outflows ◽  
Dark Clouds ◽  
Dense Cores ◽  
Large Scale Survey

We have been surveying dense molecular cores in Ophiuchus region including ρ Oph, L234, and L43 with the 4m radio telescope at Nagoya University since 1985. We have already mapped ∼18° × 12° area with 2′ or 4′ grid spacing in 13CO (J=1-0) spectra. We have identified ∼50 dense cores (we call ”13CO cores”). Typical mass, density, and size of the 13CO cores are ∼20 M⊙, ∼3 × 103 cm−3, and ∼0.3 pc, respectively (Nozawa et al. 1990). We also surveyed molecular outflows in 12CO (J=1-0) spectra toward 13 IRAS point sources associated with 13CO cores in Ophiuchus. As a result of the survey, we have found 5 molecular outflows in the filamentary dark clouds and 5 regions exhibiting high velocity wings in the ρ Oph main body.

scholarly journals ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions – I. Survey description and a first look at G9.62+0.19

2020 ◽  
Vol 496 (3) ◽  
pp. 2790-2820 ◽  
Author(s):  
Tie Liu ◽  
Neal J Evans ◽  
Kee-Tae Kim ◽  
Paul F Goldsmith ◽  
Sheng-Yuan Liu ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Star Formation ◽  
Survey Data ◽  
Massive Star ◽  
High Mass ◽  
Dense Gas ◽  
Star Forming ◽  
Star Forming Regions ◽  
Stellar Feedback ◽  
Dense Cores

ABSTRACT The ATOMS, standing for ALMA Three-millimeter Observations of Massive Star-forming regions, survey has observed 146 active star-forming regions with ALMA band 3, aiming to systematically investigate the spatial distribution of various dense gas tracers in a large sample of Galactic massive clumps, to study the roles of stellar feedback in star formation, and to characterize filamentary structures inside massive clumps. In this work, the observations, data analysis, and example science of the ATOMS survey are presented, using a case study for the G9.62+0.19 complex. Toward this source, some transitions, commonly assumed to trace dense gas, including CS J = 2−1, HCO+J = 1−0, and HCN J = 1−0, are found to show extended gas emission in low-density regions within the clump; less than 25 per cent of their emission is from dense cores. SO, CH3OH, H13CN, and HC3N show similar morphologies in their spatial distributions and reveal well the dense cores. Widespread narrow SiO emission is present (over ∼1 pc), which may be caused by slow shocks from large–scale colliding flows or H ii regions. Stellar feedback from an expanding H ii region has greatly reshaped the natal clump, significantly changed the spatial distribution of gas, and may also account for the sequential high-mass star formation in the G9.62+0.19 complex. The ATOMS survey data can be jointly analysed with other survey data, e.g. MALT90, Orion B, EMPIRE, ALMA_IMF, and ALMAGAL, to deepen our understandings of ‘dense gas’ star formation scaling relations and massive protocluster formation.

scholarly journals Feedback and Feeding in the Context of Galaxy Evolution with SPICA: Direct Characterisation of Molecular Outflows and Inflows

2017 ◽  
Vol 34 ◽  
Author(s):  
E. González-Alfonso ◽  
L. Armus ◽  
F. J. Carrera ◽  
V. Charmandaris ◽  
A. Efstathiou ◽  
...  
Keyword(s):  
Fine Structure ◽  
Galaxy Evolution ◽  
Far Infrared ◽  
Molecular Outflows ◽  
Line Shapes ◽  
Infrared Telescope ◽  
Molecular Lines ◽  
The Universe ◽  
Fine Structure Lines

AbstractA far-infrared observatory such as the SPace Infrared telescope for Cosmology and Astrophysics, with its unprecedented spectroscopic sensitivity, would unveil the role of feedback in galaxy evolution during the last ~10 Gyr of the Universe (z = 1.5–2), through the use of far- and mid-infrared molecular and ionic fine structure lines that trace outflowing and infalling gas. Outflowing gas is identified in the far-infrared through P-Cygni line shapes and absorption blueshifted wings in molecular lines with high dipolar moments, and through emission line wings of fine-structure lines of ionised gas. We quantify the detectability of galaxy-scale massive molecular and ionised outflows as a function of redshift in AGN-dominated, starburst-dominated, and main-sequence galaxies, explore the detectability of metal-rich inflows in the local Universe, and describe the most significant synergies with other current and future observatories that will measure feedback in galaxies via complementary tracers at other wavelengths.

scholarly journals Fate Before Function: Specification of the Hair Follicle Niche Occurs Prior to its Formation and Is Progenitor Dependent

2018 ◽  
Author(s):  
Ka-Wai Mok ◽  
Nivedita Saxena ◽  
Nicholas Heitman ◽  
Laura Grisanti ◽  
Devika Srivastava ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Single Cell ◽  
Hair Follicle ◽  
Cell Fate ◽  
Cluster Formation ◽  
Developmental Trajectory ◽  
List Type ◽  
Molecular Events ◽  
Niche Formation ◽  
And Function

SUMMARYCell fate transitions are essential for specialization of stem cells and their niches, but the precise timing and sequence of molecular events during embryonic development are largely unknown. Here, we show that dermal condensates (DC), signaling niches for epithelial progenitors in hair placodes, are specified before niche formation and function. With 3D/4D microscopy we identify unclustered DC precursors. With population-based and single-cell transcriptomics we define a molecular time-lapse of dynamic niche signatures and the developmental trajectory as the DC lineage emerges from fibroblasts. Co-expression of downregulated fibroblast and upregulated DC genes in niche precursors reveals a transitory molecular state following a proliferation shutdown. Waves of transcription factor and signaling molecule expression then consolidate DC niche formation. Finally, ablation of epidermal Wnt signaling and placode-derived FGF20 demonstrates their requirement for DC-precursor specification. These findings uncover a progenitor-dependent niche precursor fate and the transitory molecular events controlling niche formation and function.Graphical AbstractHIGHLIGHTSPrecursors of the hair follicle niche are specified before niche cluster formationBulk/single cell RNA-seq defines early niche fate at molecular transitional stateSuccessive waves of transcription factor/signaling genes mark niche fate acquisitionNiche fate acquisition is not “pre-programmed” and requires FGF20 from progenitors

scholarly journals A Flattened Cloud Core in NGC 2024

1994 ◽  
Vol 140 ◽  
pp. 262-263
Author(s):  
P. T. P. Ho ◽  
Y-L. Peng ◽  
J. M. Torrelles ◽  
J. F. Gómez ◽  
L. F. Rodríguez ◽  
...  
Keyword(s):  
High Velocity ◽  
Far Infrared ◽  
Gravitational Energy ◽  
Ammonia Emission ◽  
Molecular Gas ◽  
Internal Heating ◽  
Molecular Outflows ◽  
Heating Source ◽  
Molecular Lines ◽  
Cloud Core

With the VLA in the D configuration we have mapped the (J,K) = (1,1) and (2,2) NH3 lines toward a molecular cloud core in NGC 2024. This region, which contains one of the most highly collimated molecular outflows (Richer et al. 1992), has been studied extensively using a variety of techniques, including dust continuum in the far-infrared (FIR) wavelengths (Mezger et al. 1988, 1992), and molecular lines (see Barnes & Crutcher 1992 and references therein). We find that the molecular condensations associated with FIR 5, 6, and 7 (Mezger et al. 1988, 1992) have kinetic temperatures TK ≃ 40 K. We also find a perturbation of the molecular gas near FIR 6 and FIR 7 in terms of broadening of the ammonia lines. These results suggest that these condensations may not be protostars heated by gravitational energy released during collapse, but that they have an internal heating source. A flattened structure of ammonia emission is found extending parallel to the unipolar CO outflow structure, but displaced systematically to the east. The location of the high velocity outflow along the surface of the NH3 structure suggests that a wind is sweeping material from the surface of this elongated cloud core. Figure 1 is an overlay of the VLA ammonia emission (dotted area) on top of the C18O emission (thick contours) and the CO outflow (thin contours).

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