Anisotropic mass outflow in regions of star formation

Rodríguez, L. F.; Carral, P.; Ho, Paul T. P.; Moran, J. M.

doi:10.1086/160285

Cited by 49 publications

(48 citation statements)

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“…These observations of molecular outflows from protostars have shown that the timeaveraged flow energetic parameters, viz., the mechanical luminosity (L mech ) and the momentum flux or outflow force (F CO ), are correlated with the bolometric luminosity of the protostar, L bol  (Rodriguez et al 1982;Bally & Lada 1983;Lada 1985;Snell 1987;Cabrit & Bertout 1992;Bontemps et al 1996;Wu et al 2004;Hatchell et al 2007a;Takahashi et al 2008;Curtis et al 2010). A few of these studies also found an evolutionary trend in the outflow force (F CO ) with protostellar age (Bontemps et al 1996;Curtis et al 2010).…”

Section: Introductionmentioning

confidence: 99%

The Evolution of Far-Infrared Co Emission From Protostars

Manoj

Green

Megeath

et al. 2016

ApJ

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We investigate the evolution of far-IR CO emission from protostars observed with Herschel/PACS for 50 sources from the combined sample of HOPS and DIGIT Herschel key programs. From the uniformly sampled spectral energy distributions, whose peaks are well sampled, we computed the L bol , T bol ,and L L bol smm for these sources to search for correlations between far-IR CO emission and protostellar properties. We find a strong and tight correlation between far-IR CO luminosity (L CO fir ) and the bolometric luminosity (L bol ) of the protostars with µ L L CO fir bol 0.7 . We, however, do not find a strong correlation between L CO fir and protostellar evolutionary indicators, T bol and L L bol smm . FIRCO emission from protostars traces the currently shocked gas by jets/outflows, and far-IR CO luminosity, L CO fir , is proportional to the instantaneous mass-loss rate,Ṁ out . The correlation between L CO fir and L bol , then, is indicative of instantaneousṀ out tracking instantaneousṀ acc . The lack of acorrelation between L CO fir and evolutionary indicators T bol and L L bol smm suggests thatṀ out and, therefore,Ṁ acc do not show any clear evolutionary trend. These results are consistent with mass accretion/ejection in protostars being episodic. Taken together with the previous finding that the time-averaged mass-ejection/accretion rate declines during the protostellar phase, our results suggest that the instantaneous accretion/ejection rate of protostars is highly time variable and episodic, but the amplitude and/or frequency of this variability decreases with time such that the timeaveraged accretion/ejection rate declines with system age.

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Section: Introductionmentioning

confidence: 99%

The Evolution of Far-Infrared Co Emission From Protostars

Manoj

Green

Megeath

et al. 2016

ApJ

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“…For example, it is not clear if the collimation is correlated with the driving force. The correlation among bolometric luminosity of the center source, the required force and mechanical luminosity was investigated by Bally & Lada (1983) and Rodríguez et al (1982). As the correlation was discovered to be weak, a larger sample is required.…”

Section: Introductionmentioning

confidence: 99%

A study of high velocity molecular outflows with an up-to-date sample

Wu¹,

Wei²,

Zhao³

et al. 2004

A&A

294

291

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Abstract.A statistical study of the properties of molecular outflows is performed based on an up-to-date sample. 391 outflows were identified in published articles or preprints before February 28, 2003. The parameters of position, morphology, mass, energy, outflow dynamics and central source luminosity are presented for each outflow source. Outflow lobe polarity is known for all the sources, and 84% are found to be bipolar. The sources are divided into low mass and high mass groups according to either the available bolometric luminosity of the central source or the outflow mass. The pace of discovery of outflows over the past seven years has increased much more rapidly than in previous periods. Surveys for outflows are still continuing. The number of high-mass outflows detected (139) has considerably increased, showing that they are commonly associated with massive as well as low mass stars. Energetic mass ejection may be a common aspect of the formation of high mass as well as low mass stars. Outflow masses are correlated strongly with bolometric luminosity of the center sources, which was obtained for the first time. There are also correlations between the central source luminosity and the parameters of mechanical luminosity and the thrust or force necessary to drive the outflow. The results show that flow mass, momentum and energy depend on the nature of the central source. Despite their similarity, there are differences between the high mass and low mass outflows. Low mass outflows are more collimated than high mass outflows. On average, the mass of high mass sources can be more than two orders of magnitude larger than those of low mass outflows. The relation between flow mass and dynamical time appears to differ for the two types of outflows. Low mass sources make up 90% of outflows associated with HH objects while high mass outflows make up 61% of the sources associated with H 2 O masers. Sources with characteristics of collapse or infall comprise 12% of the entire outflow sample. The spatial distribution of the outflow sources in the Galaxy is presented and the local occurrence rate is compared with the stellar birth rate.

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“…Rodríguez et al 1982;Stahler 1994;Bachiller & Tafalla 1999;Richer et al 2000). More recently, similar behaviour has been observed in observations of the H 2 S(1) 1-0 line in various outflows (Salas & Crúz-González 2002).…”

Section: Introductionmentioning

confidence: 99%

Long-duration simulations of the evolution of jet-driven molecular outflows

Keegan¹,

Downes²

2005

A&A

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Abstract. We use numerical simulations to examine the mass-velocity, m(v), and intensity-velocity, I(v), relations in jet-driven molecular outflows up to an age of 2300 yr. We find that the m(v) relation is a power-law, m(v) ∝ v −γ , the exponent of which increases with time up to γ ≈ 1.6 at t ≈ 1500 yr. It then becomes roughly constant. This indicates that γ does not evolve throughout the lifetime of a molecular outflow, at least in the context of the jet-driven model. We also investigate the effect of long-period episodicity of the jet on the m(v) and I(v) relations. We find that, contrary to previous expectations, these relations are not significantly changed with the introduction of such variability into the jet. Finally, we present a novel, and relatively simple, parallelisation method for the code used in these simulations. This gives an increase of roughly a factor of 4 in speed over standard methods, and allows the simulations presented here to be run fairly easily, even with modest computational resources.

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Anisotropic mass outflow in regions of star formation

Cited by 49 publications

References 0 publications

The Evolution of Far-Infrared Co Emission From Protostars

The Evolution of Far-Infrared Co Emission From Protostars

A study of high velocity molecular outflows with an up-to-date sample

Long-duration simulations of the evolution of jet-driven molecular outflows

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