A Model of Molecular Emission in Bipolar Flows

Cabrit, S.; Bertout, C.

doi:10.1007/978-94-009-3887-8_19

Cited by 126 publications

(239 citation statements)

References 3 publications

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“…The values of Table 5 are similar to the results found in Cabrit & Bertout (1992) and Hogerheijde et al (1998) for other Class I outflows and also agree with the results from Olberg et al (1992) who find L kin = 4.5 × 10 −3 L and dynamical time scales of 4 × 10 4 yr. Although our dynamical time scales are a factor of 2 smaller, this can be accounted for by the smaller covered area in our observations.…”

Section: Other Outflow Propertiessupporting

confidence: 90%

APEX-CHAMP⁺high-JCO observations of low-mass young stellar objects

Kempen

Dishoeck

Güsten

et al. 2009

A&A

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Context. The spectacular outflow of HH 46/47 is driven by HH 46 IRS 1, an embedded Class I Young Stellar Object (YSO). Although much is known about this region from extensive optical and infrared observations, the properties of its protostellar envelope and molecular outflow are poorly constrained. Aims. Our aim is to characterize the size, mass, density and temperature profiles of the protostellar envelope of HH 46 IRS 1 and its surrounding cloud material as well as the effect the outflow has on its environment. Methods. The newly commisioned CHAMP + and LABOCA arrays on the APEX telescope, combined with lower frequency line receivers, are used to obtain a large (5 × 5 , 0.6 × 0.6 pc) continuum map and smaller (80 × 80 , 36 000 × 36 000 AU) heterodyne maps in various isotopologues of CO and HCO + . The high-J lines of CO (6-5 and 7-6) and its isotopologues together with [C I] 2-1, observed with CHAMP + , are used to probe the warm molecular gas in the inner few hundred AU and in the outflowing gas. The data are interpreted with continuum and line radiative transfer models. Results. Broad outflow wings are seen in CO low-and high-J lines at several positions, constraining the gas temperatures to a constant value of ∼100 K along the red outflow axis and to ∼60 K for the blue outflow. The derived outflow mass is of order 0.4-0.8 M , significantly higher than previously found. The bulk of the strong high-J CO line emission has a surprisingly narrow width, however, even at outflow positions. These lines cannot be fit by a passively heated model of the HH 46 IRS envelope. We propose that it originates from photon heating of the outflow cavity walls by ultraviolet photons originating in outflow shocks and the accretion disk boundary layers. At the position of the bow shock itself, the UV photons are energetic enough to dissociate CO. The envelope mass of ∼5 M is strongly concentrated towards HH 46 IRS with a density power law of −1.8. Conclusions. The fast mapping speed offered by CHAMP + allows the use of high-J CO lines and their isotopes to generate new insights into the physics of the interplay between the molecular outflow and protostellar envelope around low-mass protostars. The UV radiation inferred from the high-J CO and [C I] data will affect the chemistry of other species.

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Section: Other Outflow Propertiessupporting

confidence: 90%

APEX-CHAMP⁺high-JCO observations of low-mass young stellar objects

Kempen

Dishoeck

Güsten

et al. 2009

A&A

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“…We examine the well-known correlation between momentum flux and bolometric luminosity that has been proposed by Cabrit & Bertout (1992) and Bontemps et al (1996) for the homogenous sample of young protostellar objects in the Serpens Core. The outflow momentum flux F CO is plotted against the bolometric luminosity L bol in the upper panel of Fig.…”

Section: Outflow Momentum Flux and Mechanical Luminosity Versus Bolommentioning

confidence: 97%

“…There is increasing evidence that the momentum flux or "thrust" of molecular outflows is linked to the luminosity of the protostellar core (e.g. Cabrit & Bertout 1992;Bontemps et al 1996;Wu et al 2004;Hatchell et al 2007a). Such a correlation implies that, independently of the details of the mass accretion and ejection mechanisms, both quantities are energetically governed in common by infall.…”

Section: Introductionmentioning

confidence: 99%

Wide field COJ= 3 → 2 mapping of the Serpens cloud core

Dionatos

Nisini

Codella

et al. 2010

A&A

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Context. Outflows provide indirect means to gain insight into diverse star formation-associated phenomena. At the level of individual protostellar cores, both outflows and the intrinsic core properties can be used to study the mass accretion/ejection process of heavily embedded protostellar sources. Aims. The main objective of the paper is to study the overall outflow distribution and its association with the young population of the Serpens Core cluster. In addition, the paper addresses the correlation of the outflow momentum flux with the bolometric luminosity of their driving sources using this homogeneous dataset for a single star-forming site.Methods. An area comprising 460 × 230 of the Serpens cloud core was mapped in 12 CO J = 3 →2 with the HARP-B heterodyne array at the James Clerk Maxwell Telescope; J = 3 →2 observations are more sensitive tracers of hot outflow gas than lower J CO transitions; combined with the high sensitivity of the HARP-B receptors outflows are sharply outlined, enabling their association with individual protostellar cores. Results. Most of ∼20 observed outflows are found to be associated with known protostellar sources in bipolar or unipolar configurations. All but two outflow/core pairs in our sample tend to have a projected orientation spanning roughly NW-SE. The overall momentum driven by outflows in Serpens lies between 3.2 and 5.1 × 10 −1 M km s −1 , the kinetic energy from 4.3 to 6.7 × 10 43 erg, and momentum flux is between 2.8 and 4.4 × 10 −4 M km s −1 yr −1 . Bolometric luminosities of protostellar cores based on Spitzer photometry are found up to an order of magnitude lower than previous estimations derived with IRAS/ISO data. Conclusions. We confirm the validity of the existing correlations between the momentum flux and bolometric luminosity of Class I sources for the homogenous sample of Serpens, though we suggest that they should be revised by a shift to lower luminosities. All protostars classified as Class 0 sources stand well above the known Class I correlations, indicating a decline in momentum flux between the two classes.

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“…The outflow parameters and their correlations have been investigated Bally & Lada 1983;Cabrit & Bertout 1992;Shepherd & Churchwell 1996a;Ridge & Moore 2001). Mechanisms of outflow collimation and the forces driving the outflows have been proposed as well.…”

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

293

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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A Model of Molecular Emission in Bipolar Flows

Cited by 126 publications

References 3 publications

APEX-CHAMP⁺high-JCO observations of low-mass young stellar objects

APEX-CHAMP⁺high-JCO observations of low-mass young stellar objects

Wide field COJ= 3 → 2 mapping of the Serpens cloud core

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

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A Model of Molecular Emission in Bipolar Flows

Cited by 126 publications

References 3 publications

APEX-CHAMP+high-JCO observations of low-mass young stellar objects

APEX-CHAMP+high-JCO observations of low-mass young stellar objects

Wide field COJ= 3 → 2 mapping of the Serpens cloud core

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

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Product

Resources

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APEX-CHAMP⁺high-JCO observations of low-mass young stellar objects

APEX-CHAMP⁺high-JCO observations of low-mass young stellar objects