Alma Observations of the Hh 46/47 Molecular Outflow

Arce, Héctor G.; Mardones, Diego; Corder, Stuartt; Garay, Guido; Noriega-Crespo, A.; Raga, A. C.

doi:10.1088/0004-637x/774/1/39

Cited by 85 publications

(90 citation statements)

References 75 publications

(118 reference statements)

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“…Arguing against this is the smooth distribution of the gas indicating that we also recover most of the emission at low velocities with respect to υ sys (cf. the clumpy distribution in the channel maps presented by Arce et al 2013). Even though the lack of single-dish data prevents us from putting quantitative numbers on the effect of loss of short spacings, we still find it unlikely that this will significantly affect the emission in the line wings.…”

Section: Observed Line Profilesmentioning

confidence: 75%

A young bipolar outflow from IRAS 15398-3359

Bjerkeli

Jørgensen

Brinch³

2016

A&A

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Context. Changing physical conditions in the vicinity of protostars allow for a rich and interesting chemistry to occur. Heating and cooling of the gas allows molecules to be released from and frozen out on dust grains. These changes in physics, traced by chemistry as well as the kinematical information, allows us to distinguish between different scenarios describing the infall of matter and the launching of molecular outflows and jets. Aims. We aim to determine the spatial distribution of different species that are of different chemical origin. This is to examine the physical processes in play in the observed region. From the kinematical information of the emission lines we aim to determine the nature of the infalling and outflowing gas in the system. We also aim to determine the physical properties of the outflow. Methods. Maps from the Submillimeter Array (SMA) reveal the spatial distribution of the gaseous emission towards IRAS 15398-3359. The line radiative transfer code LIME is used to construct a full 3D model of the system taking all relevant components and scales into account. Results. CO, HCO + , and N 2 H + are detected and shown to trace the motions of the outflow. For CO, the circumstellar envelope and the surrounding cloud also have a profound impact on the observed line profiles. N 2 H + is detected in the outflow, but is suppressed towards the central region, perhaps because of the competing reaction between CO and H + 3 in the densest regions as well as the destruction of N 2 H + by CO. N 2 D + is detected in a ridge south-west of the protostellar condensation and is not associated with the outflow. The morphology and kinematics of the CO emission suggests that the source is younger than ∼1000 years. The mass, momentum, momentum rate, mechanical luminosity, kinetic energy, and mass-loss rate are also all estimated to be low. A full 3D radiative transfer model of the system can explain all the kinematical and morphological features in the system.

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Section: Observed Line Profilesmentioning

confidence: 75%

A young bipolar outflow from IRAS 15398-3359

Bjerkeli

Jørgensen

Brinch³

2016

A&A

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“…Moreover, those for the Class 0 source L1448C (L1448 mm) in Perseus are reported by Hirano et al (2010), and those for the HH 46/47 molecular outflow on the outskirts of the Gum Nebula by Arce et al (2013). The outflow parameters for these sources are summarized in Table 2.…”

Section: Comparison With Other Sourcesmentioning

confidence: 99%

“…Thus, the wall of the outflow cavity has a parabolic shape, and it is linearly accelerated with increasing distance from the protostar along the outflow axis and with increasing distance from the outflow axis. Such a parabolic model is widely applied to various low-mass and high-mass protostellar sources (e.g., Beuther et al 2004;Yeh et al 2008;Takahashi & Ho 2012;Arce et al 2013;Takahashi et al 2013;Lumbreras & Zapata 2014;Zapata et al 2014). The blue lines shown in Figure 3 represent the best-fit result by eye, where the inclination angle is fixed to +5°, which is derived from the kinematic structure in the envelope.…”

Section: Outflowmentioning

confidence: 99%

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Geometric and Kinematic Structure of the Outflow/Envelope System of L1527 Revealed by Subarcsecond-Resolution Observation of Cs

Oya

Sakai

Leflóch

et al. 2015

ApJ

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Subarcsecond-resolution images of the rotational line emissions of CS and c-C 3 H 2 obtained toward the low-mass protostar IRAS 04368+2557 in L1527 with the Atacama Large Millimeter/submillimeter Array are investigated to constrain the orientation of the outflow/envelope system. The distribution of CS consists of an envelope component extending from north to south and a faint butterfly shaped outflow component. The kinematic structure of the envelope is well reproduced by a simple ballistic model of an infalling rotating envelope. Although the envelope has a nearly edge-on configuration, we find that the western side of the envelope faces the observer. This configuration is opposite to the direction of the large-scale (∼10 4 AU) outflow suggested previously from the 12 CO (J = 3-2) observation, and to the morphology of infrared reflection near the protostar (∼200 AU). The latter discrepancy could originate from high extinction by the outflow cavity of the western side, or may indicate that the outflow axis is not parallel to the rotation axis of the envelope. Position-velocity diagrams show the accelerated outflow cavity wall, and its kinematic structure in the 2000 AU scale is explained by a standard parabolic model with the inclination angle derived from the analysis of the envelope. The different orientation of the outflow between the small and large scale implies a possibility of precession of the outflow axis. The shape and the velocity of the outflow in the vicinity of the protostar are compared with those of other protostars.

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“…Based on large-scale variability surveys, the strongest bursts -with accretion rates of at least 100 times the quiescent value -happen every 5-50 kyr per protostar (Scholz et al 2013). The spacings between periodic shocks in jets and outflows support quiescent intervals anywhere from 10 4 yr down to 10 yr, separating bursts with an unknown range of accretion rates (Devine et al 1997;Raga et al 2002;Arce et al 2013). Highcadence photometric surveys show luminosity variations at the 5-50% level on timescales of hours to weeks (Billot et al 2012;Stauffer et al 2014), though only some of that may be related to accretion variability (Morales-Calderón et al 2011;Rebull et al 2014).…”

Section: And For Fuormentioning

confidence: 99%

Chemical tracers of episodic accretion in low-mass protostars

Visser

Bergin

Jørgensen

2015

A&A

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Aims. Accretion rates in low-mass protostars can be highly variable in time. Each accretion burst is accompanied by a temporary increase in luminosity, heating up the circumstellar envelope and altering the chemical composition of the gas and dust. This paper aims to study such chemical effects and discusses the feasibility of using molecular spectroscopy as a tracer of episodic accretion rates and timescales. Methods. We simulate a strong accretion burst in a diverse sample of 25 spherical envelope models by increasing the luminosity to 100 times the observed value. Using a comprehensive gas-grain network, we follow the chemical evolution during the burst and for up to 10 5 yr after the system returns to quiescence. The resulting abundance profiles are fed into a line radiative transfer code to simulate rotational spectra of C 18 O, HCO + , H 13 CO + , and N 2 H + at a series of time steps. We compare these spectra to observations taken from the literature and to previously unpublished data of HCO + and N 2 H + 6−5 from the Herschel Space Observatory. Results. The bursts are strong enough to evaporate CO throughout the envelope, which in turn enhances the abundance of HCO + and reduces that of N 2 H + . After the burst, it takes 10 3 -10 4 yr for CO to refreeze and for HCO + and N 2 H + to return to normal. The H 2 O snowline expands outwards by a factor of ∼10 during the burst; afterwards, it contracts again on a timescale of 10 2 -10 3 yr. The chemical effects of the burst remain visible in the rotational spectra for as long as 10 5 yr after the burst has ended, highlighting the importance of considering luminosity variations when analyzing molecular line observations in protostars. The spherical models are currently not accurate enough to derive robust timescales from single-dish observations. As follow-up work, we suggest that the models be calibrated against spatially resolved observations in order to identify the best tracers to be used for statistically significant source samples.

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Alma Observations of the Hh 46/47 Molecular Outflow

Cited by 85 publications

References 75 publications

A young bipolar outflow from IRAS 15398-3359

A young bipolar outflow from IRAS 15398-3359

Geometric and Kinematic Structure of the Outflow/Envelope System of L1527 Revealed by Subarcsecond-Resolution Observation of Cs

Chemical tracers of episodic accretion in low-mass protostars

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