Multiline Observations of Molecular Bullets from a High-mass Protostar

Cheng, Yu; Qiu, Keping; Zhang, Qizhou; Wyrowski, F.; Menten, K. M.; Güsten, R.

doi:10.3847/1538-4357/ab15d4

Cited by 7 publications

(4 citation statements)

References 76 publications

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“…We take this to be the width of the knot. Millimeter and sub-millimeter observations towards the central region of the jet have shown that the number density observed here is approximately in the range 10 4 −10 5 cm −3 (Hunter et al, 2000;Qiu et al, 2019;Cheng et al, 2019).…”

Section: Iras 18162-2048supporting

confidence: 50%

Modeling of thermal and non-thermal radio emission from HH80-81 jet

Sreelekshmi¹,

Vig²,

Mandal³

2023

Preprint

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Protostellar jets are one of the primary signposts of star formation. A handful of protostellar objects exhibit radio emission from ionized jets, of which a few display negative spectral indices, indicating the presence of synchrotron emission. In this study, we characterize the radio spectra of HH80-81 jet with the help of a numerical model that we have developed earlier, which takes into account both thermal free-free and non-thermal synchrotron emission mechanisms. For modeling the HH80-81 jet, we consider jet emission towards the central region close to the driving source along with two Herbig-Haro objects, HH80 and HH81. We have obtained the best-fit parameters for each of these sources by fitting the model to radio observational data corresponding to two frequency windows taken across two epochs. Considering an electron number density in the range 10 3 − 10 5 cm −3 , we obtained the thickness of the jet edges and fraction of relativistic electrons that contribute to non-thermal emission in the range 0.01 • − 0.1 • and 10 −7 − 10 −4 , respectively. For the best-fit parameter sets, the model spectral indices lie in the range of -0.15 to +0.11 within the observed frequency windows.

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Section: Iras 18162-2048supporting

confidence: 50%

Modeling of thermal and non-thermal radio emission from HH80-81 jet

Sreelekshmi¹,

Vig²,

Mandal³

2023

Preprint

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“…As for high-mass protostars, current outflow studies often are limited by their angular resolution (Beuther et al 2007;Maud et al 2015;Cunningham et al 2016) or are focused on a handful of objects only (Duarte-Cabral et al 2013;Cheng et al 2019). Surveys with high-angular resolution in high-mass star-forming regions are thus unavoidable to characterize high-mass protostellar outflows and finally constrain the mass-loss or even accretion history of high-mass protostars.…”

Section: Introductionmentioning

confidence: 99%

Episodic accretion constrained by a rich cluster of outflows

Nony

Motte

Louvet

et al. 2020

A&A

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Context. The accretion history of protostars remains widely mysterious even though it represents one of the best ways to understand the protostellar collapse that leads to the formation of stars. Aims. Molecular outflows, which are easier to detect than the direct accretion onto the prostellar embryo, are here used to characterize the protostellar accretion phase in W43-MM1. Methods. The W43-MM1 protocluster host a sufficient number of protostars to statistically investigate molecular outflows in a single, homogeneous region. We used the CO(2-1) and SiO(5-4) line datacubes, taken as part of an ALMA mosaic with a 2000 AU resolution, to search for protostellar outflows, evaluate the influence that the environment has on these outflows' characteristics and put constraints on outflow variability in W43-MM1. Results. We discovered a rich cluster of 46 outflow lobes, driven by 27 protostars with masses of 1−100 M . The complex environment inside which these outflow lobes develop has a definite influence on their length, limiting the validity of using outflows' dynamical timescales as a proxy of the ejection timescale in clouds with high dynamics and varying conditions. We performed a detailed study of Position-Velocity (PV) diagrams of outflows that revealed clear events of episodic ejection. The time variability of W43-MM1 outflows is a general trend and is more generally observed than in nearby, low-to intermediate-mass star-forming regions. The typical timescale found between two ejecta, ∼500 yr, is consistent with that found in nearby protostars.Conclusions. If ejection episodicity reflects variability in the accretion process, either protostellar accretion is more variable or episodicity is easier to detect in high-mass star-forming regions than in nearby clouds. The timescale found between accretion events could be resulting from instabilities, associated with bursts of inflowing gas arising from the close dynamical environment of highmass star-forming cores.

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“…Episodic variation of, e.g., mass-loss rate and flow velocity, in a protostellar ejection can produce internal shocks. This mechanism has been proposed to produce emission knots (which correspond to the Hubble Wedge in the PV diagram) in molecular outflows (Arce & Goodman 2001;Arce et al 2007;Vorobyov et al 2018;Cheng et al 2019;Rohde et al 2019). Since the accretion is episodic, the outflow as a natural consequence of the accretion is episodic as well (Kuiper et al 2015;Bally 2016;Cesaroni et al 2018).…”

Section: Episodic Ejectionmentioning

confidence: 97%

The ALMA Survey of 70 $μ\rm m$ Dark High-mass Clumps in Early Stages (ASHES). II: Molecular Outflows in the Extreme Early Stages of Protocluster Formation

Li,

Sanhueza,

Zhang

et al. 2020

Preprint

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We present a study of outflows at extremely early stages of high-mass star formation obtained from the ALMA Survey of 70 µm dark High-mass clumps in Early Stages (ASHES). Twelve massive 3.6−70 µm dark prestellar clump candidates were observed with the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 6. Forty-three outflows are identified toward 41 out of 301 dense cores using the CO and SiO emission lines, yielding a detection rate of 14%. We discover 6 episodic molecular outflows associated with low-to high-mass cores, indicating that episodic outflows (and therefore episodic accretion) begin at extremely early stages of protostellar evolution for a range of core masses. The time span between consecutive ejection events is much smaller than those found in more evolved stages, which indicates that the ejection episodicity timescale is likely not constant over time. The estimated outflow dynamical timescale appears to increase with core masses, which likely indicates that more massive cores have longer accretion timescales than less massive cores. The lower accretion rates in these 70 µm dark objects compared to the more evolved protostars indicate that the accretion rates increase with time. The total outflow energy rate is smaller than the turbulent energy dissipation rate, which suggests that outflow induced turbulence cannot sustain the internal clump turbulence at the current epoch. We often detect thermal SiO emission within these 70 µm dark clumps that is unrelated to CO outflows. This SiO emission could be produced by collisions, intersection flows, undetected protostars, or other motions.

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Multiline Observations of Molecular Bullets from a High-mass Protostar

Cited by 7 publications

References 76 publications

Modeling of thermal and non-thermal radio emission from HH80-81 jet

Modeling of thermal and non-thermal radio emission from HH80-81 jet

Episodic accretion constrained by a rich cluster of outflows

The ALMA Survey of 70 $μ\rm m$ Dark High-mass Clumps in Early Stages (ASHES). II: Molecular Outflows in the Extreme Early Stages of Protocluster Formation

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