Entrainment Mechanisms for Outflows in the L1551 Star‐forming Region

Stojimirović, Irena; Narayanan, Gopal; Snell, R. L.; Bally, John

doi:10.1086/506340

Cited by 42 publications

(69 citation statements)

References 76 publications

(161 reference statements)

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“…In the velocity range from 4 to 10 km s −1 , a narrower elongated structure appears at the northeast of IRS 5 and through NE, which could still be a mix of the outflows from both sources. In the velocity range from 2 to 6 km s −1 , a clam-shaped emission shows up around the HL Tau group, which is identified as the collective outflows from the HL Tau group (Mundt et al 1990;Stojimirović et al 2006;Yoshida et al 2010). This outflow structure extends to ∼14 km s −1 in the redshifted lobe.…”

Section: Discussionmentioning

confidence: 99%

“…This component is located between the redshifted outflows from IRS 5 and NE and the collective outflows from the HL Tau group , which could be the result of the outflow interaction. In the velocity range from 8 to 16 km s −1 , another narrow elongated emission is distributed in the east-west direction pointing back to IRS 5 and NE, but the origin of this east-west outflow is still unclear (Moriarty-Schieven & Wannier 1991;Pound & Bally 1991;Reipurth et al 2002;Stojimirović et al 2006). At 10 km s −1 , a diffused emission with an intensity of ∼2-4 K is distributed at the southeast of the L 1551 molecular cloud, and this is part of the ambient gas in Taurus (Yoshida et al 2010).…”

Section: Discussionmentioning

confidence: 99%

“…Thus, we assume the excitation temperature of C 18 O is the dust temperature, but we try both T CO and T dust for 13 CO for comparison. On the other hand, since Stojimirović et al (2006) used the two rotational transitions of 12 CO ( J = 1-0 and 3-2) to derive a mean excitation temperature of the main NE/IRS 5 outflow to be 16.5 K, which is generally higher than T CO , we also use this temperature for comparison. Therefore, we compare the derived abundance ratios under the following four assumptions: .…”

Section: Influence Of the Excitation Temperaturementioning

confidence: 99%

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The Intrinsic Abundance Ratio and X-Factor of Co Isotopologues in L 1551 Shielded From Fuv Photodissociation

Lin

Shimajiri

Hara

et al. 2016

ApJ

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We investigate the intrinsic abundance ratio of 13 CO to C 18 O and the X-factor in L 1551 using the Nobeyama Radio Observatory (NRO) 45 m telescope. L 1551 is chosen because it is relatively isolated in the Taurus molecular cloud shielded from FUV photons, providing an ideal environment for studying the target properties. Our observations cover~¢´¢ 40 40 with a resolution of~ 30 , which make up maps with the highest spatial dynamical range to date. We derive the X Xvalue on the sub-parsec scales in the range of ∼3-27 with a mean value of 8.0 ± 2.8. Comparing to the visual extinction map derived from the Herschel observations, we found that the abundance ratio reaches its maximum at low A V (i.e., A V ∼ 1-4 mag), and decreases to the typical solar system value of 5.5 inside L 1551 MC. The high X Xvalue at the boundary of the cloud is most likely due to the selective FUV photodissociation of C 18 O. This is in contrast with Orion-A where internal OB stars keep the abundance ratio at a high level, greater than ∼10. In addition, we explore the variation of the X-factor, because it is an uncertain, but widely used, quantity in extragalactic studies. We found that the X-factor µN H 1.0 2 , which is consistent with previous simulations. Excluding the high density region, the average X-factor is similar to the Milky Way average value.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Influence Of the Excitation Temperaturementioning

confidence: 99%

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The Intrinsic Abundance Ratio and X-Factor of Co Isotopologues in L 1551 Shielded From Fuv Photodissociation

Lin

Shimajiri

Hara

et al. 2016

ApJ

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“…The total kinetic energy contained in the eleven outflows was estimated from the total momentum as follows: E tot = flows 1/2×P flow ×V char ∼ 3.4 × 10 44 -1 × 10 45 ergs. We also estimated the rate of kinetic energy deposited by the outflows in the surrounding medium as: L tot = 1/2 × F tot × V esc , where V esc is the escape velocity of the cloud V esc = √ 2GM cloud /R cloud ∼ 5 km s −1 (Stojimirović et al 2006). In this way, we found a total mechanical luminosity…”

Section: Outflow Dynamical Parametersmentioning

confidence: 95%

Probing the role of protostellar feedback in clustered star formation

Maury

André

2009

A&A

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Context. The role played by protostellar feedback in clustered star formation is still a matter of debate. In particular, protostellar outflows have been proposed as a source of turbulence in cluster-forming clumps, which may provide support against global collapse for several free-fall times. Aims. Here, we seek to test the above hypothesis in the case of the well-documented NGC 2264-C protocluster, by quantifying the amount of turbulence and support injected in the surrounding medium by protostellar outflows. Methods. Using the HERA heterodyne array on the IRAM 30 m telescope, we carried out an extensive mapping of NGC 2264-C in the three molecular line transitions 12 CO(2-1), 13 CO(2-1), and C 18 O(2-1). Results. We found widespread high-velocity 12 CO emission, testifying to the presence of eleven outflow lobes, closely linked to the compact millimeter continuum sources previously detected in the protocluster. We carried out a detailed analysis of the dynamical parameters of these outflows, including a quantitative evaluation of the overall momentum flux injected in the cluster-forming clump. These dynamical parameters were compared to the gravitational and turbulent properties of the clump. Conclusions. We show that the population of protostellar outflows identified in NGC 2264-C is likely to contribute a significant fraction of the observed turbulence but cannot efficiently support the protocluster against global collapse. Gravity appears to largely dominate the dynamics of the NGC 2264-C clump at the present time; however it is possible that an increase in the star formation rate during the later evolution of the protocluster will trigger enough outflows to finally halt the contraction of the cloud.

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“…We assume a constant excitation temperature of 15 K for the molecular gas, although variations from 9 to 25 K may exist (Swift et al 2005;Stojimirović et al 2006;Snell 1981). There is a linear correlation between both the -corrected 13 CO and the C 18 O column depth with A V between $2 and 10 mag.…”

Section: Mass and Abundancesmentioning

confidence: 99%

A Case Study of Low‐Mass Star Formation

Swift¹,

Welch

2008

ASTROPHYS J SUPPL S

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This article synthesizes observational data from an extensive program aimed toward a comprehensive understanding of star formation in a low-mass star-forming molecular cloud. New observations and published data spanning from the centimeter wave band to the near-infrared reveal the high-and low-density molecular gas, dust, and premain-sequence stars in L1551. The total cloud mass of $160 M contained within 0.9 pc has a dynamical timescale, t dyn ¼ 1:1 Myr. Thirty-five pre-main-sequence stars with masses from $0.1 to 1.5 M are selected to be members of the L1551 association constituting a total of 22 AE 5 M of stellar mass. The observed star formation efficiency, SFE ¼ 12%, while the total efficiency, SFE tot , is estimated to fall between 9% and 15%. L1551 appears to have been forming stars for several t dyn , with the rate of star formation increasing with time. Star formation has likely progressed from east to west, and there is clear evidence that another star or stellar system will form in the high column density region to the northwest of L1551 IRS 5. High-resolution, wide-field maps of L1551 in CO isotopologue emission display the structure of the molecular cloud at 1600 AU physical resolution. The 13 CO emission clearly reveals the disruption of the ambient cloud by outflows in the line core and traces the interface between regions of outflow and quiescent gas in the line wings. Kinetic energy from outflows is being deposited back into the cloud on a physical scale k peak % 0:05 pc at a rate,Ė input % 0:05 L . The remaining energy afforded by the full mechanical luminosity of outflow in L1551 destroys the cloud or is otherwise lost to the greater interstellar medium. The C 18 O emission is optically thin and traces well the turbulent velocity structure of the cloud. The total turbulent energy is close to what is expected from virial equilibrium. The turbulent velocities exist primarily on small scales in the cloud, and the energy spectrum of turbulent fluctuations, E(k) / k À , is derived by various methods to have % 1 2. The turbulent dissipation rate estimated using the results of current numerical simulations isĖ diss %Ė input . This study reveals that stellar feedback is a significant factor in the evolution of the L1551 cloud.

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Entrainment Mechanisms for Outflows in the L1551 Star‐forming Region

Cited by 42 publications

References 76 publications

The Intrinsic Abundance Ratio and X-Factor of Co Isotopologues in L 1551 Shielded From Fuv Photodissociation

The Intrinsic Abundance Ratio and X-Factor of Co Isotopologues in L 1551 Shielded From Fuv Photodissociation

Probing the role of protostellar feedback in clustered star formation

A Case Study of Low‐Mass Star Formation

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