Discovery of a Highly Collimated Molecular Outflow in the Southern Bok Globule BHR 71

Bourke, Tyler L.; Garay, Guido; Lehtinen, K.; Köhnenkamp, Ive; Launhardt, R.; Nyman, L. A.; May, J.; Robinson, G.; Hyland, A. R.

doi:10.1086/303642

Cited by 123 publications

(164 citation statements)

References 44 publications

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“…6 yields a column density N(H 2 ) ∼ 6.9 × 10 19 cm −2 , whereas linearly fitting the (v = 0, J = 0, 1) part of the modelled rotational diagram yields N(H 2 ) ∼ 1.8 × 10 21 cm −2 , which is 26 times larger than that measured based only on the observations. Moreover, our value is consistent with the total mass of 1M for the northern lobe determined by Bourke et al (1997) based on CO (1−0) and (2−1) line observations (combined with 13 CO and C 18 O (1-0)). From a different perspective, the value that we found is simultaneously ∼50 times smaller than that found in the bright CO positions of the W44 SNR studied in the same way by Anderl et al (2014), where molecular shocks also propagate.…”

Section: Employing Shock Models: Energeticssupporting

confidence: 90%

Impacts of pure shocks in the BHR71 bipolar outflow

Gusdorf

Riquelme

Anderl

et al. 2015

A&A

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Context. During the formation of a star, material is ejected along powerful jets that impact the ambient material. This outflow regulates star formation by e.g. inducing turbulence and heating the surrounding gas. Understanding the associated shocks is therefore essential to the study of star formation. Aims. We present comparisons of shock models with CO, H 2 , and SiO observations in a "pure" shock position in the BHR71 bipolar outflow. These comparisons provide an insight into the shock and pre-shock characteristics, and allow us to understand the energetic and chemical feedback of star formation on Galactic scales. Methods. New CO (J up = 16, 11, 7, 6, 4, 3) observations from the shocked regions with the SOFIA and APEX telescopes are presented and combined with earlier H 2 and SiO data (from the Spitzer and APEX telescopes). The integrated intensities are compared to a grid of models that were obtained from a magneto-hydrodynamical shock code, which calculates the dynamical and chemical structure of these regions combined with a radiative transfer module based on the "large velocity gradient" approximation. Results. The CO emission leads us to update the conclusions of our previous shock analysis: pre-shock densities of 10 4 cm −3 and shock velocities around 20−25 km s −1 are still constrained, but older ages are inferred (∼4000 years). Conclusions. We evaluate the contribution of shocks to the excitation of CO around forming stars. The SiO observations are compatible with a scenario where less than 4% of the pre-shock SiO belongs to the grain mantles. We infer outflow parameters: a mass of 1.8 × 10 −2 M was measured in our beam, in which a momentum of 0.4 M km s −1 is dissipated, corresponding to an energy of 4.2 × 10 43 erg. We analyse the energetics of the outflow species by species. Comparing our results with previous studies highlights their dependence on the method: H 2 observations only are not sufficient to evaluate the mass of outflows.

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Section: Employing Shock Models: Energeticssupporting

confidence: 90%

Impacts of pure shocks in the BHR71 bipolar outflow

Gusdorf

Riquelme

Anderl

et al. 2015

A&A

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“…One of the signatures of high-mass star formation are the powerful molecular outflows observed toward these regions (Shepherd et al 2007;Bourke et al 1997). Because FIR 10 is a massive core, it is likely that outflowing motions are present or will develop over time.…”

Section: An Outflow In G3079 Fir 10?mentioning

confidence: 99%

G30.79 FIR 10: a gravitationally bound infalling high-mass star-forming clump

Cortés

Parra

Cortés

et al. 2010

A&A

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Context. The process of high-mass star formation is still shrouded in controversy. Models are still tentative and current observations are just beginning to probe the densest inner regions of giant molecular clouds. Aims. The study of high-mass star formation requires the observation and analysis of high-density gas. This can be achieved by the detection of emission from higher rotational transitions of molecules in the sub-millimeter. Here, we studied the high-mass clump G30.79 FIR 10 by observing molecular emission in the 345 GHz band. The goal is to understand the gravitational state of this clump, considering turbulence and magnetic fields, and to study the kinematics of dense gas. Methods. We approached this region by mapping the spatial distribution of HCO + (J = 4 → 3), H 13 CO + (J = 4 → 3), CS(J = 7 → 6), 12 CO(J = 3 → 2), and 13 CO(J = 3 → 2) molecular emission by using the ASTE telescope and by observing the 12 C 18 O(J = 3 → 2), HCN(J = 4 → 3), and H 13 CN(J = 4 → 3) molecular transitions with the APEX telescope. Results. Infalling motions were detected and modeled toward this source. A mean infall velocity of 0.5 km s −1 with an infall mass rate of 5 × 10 −3 M yr −1 was obtained. Also, a previously estimated value for the magnetic field strength in the plane of the sky was refined to be 855 μG which we used to calculate a mass-to-magnetic flux ratio, λ = 1.9, or super-critical. The virial mass from turbulent motions was also calculated finding M vir = 563 M , which gives a ratio of M submm /M vir = 5.9. Both values strongly suggest that this clump must be in a state of gravitational collapse. Additionally, we estimated the HCO + abundance, obtaining X(HCO + ) = 2.4×10 −10 .

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“…Its observation by the Herschel telescope is guaranteed through the key-program WISH, and also DIGIT. The associated outflow region contains signatures of two distinct molecular jets (Bourke et al 1997;Myers & Mardones 1998;Parise et al 2006) centered on two different protostellar sources, IRS1 and IRS2 (Bourke 2001) separated by ∼3400 AU. Bright HH objects are associated with the blue-shifted lobes of each outflow, HH320 and HH321 (Corporon & Reipurth 1997).…”

Section: Introductionmentioning

confidence: 99%

Revisiting the shocks in BHR71: new observational constraints and H₂O predictions forHerschel

Giannini

Flower

Parise

et al. 2011

A&A

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Context. During the formation of a star, material is ejected along powerful jets that impact the ambient material. This outflow phenomenon plays an important role in the regulation of star formation. Understanding the associated shocks and their energetic effects is therefore essential to the study of star formation. Aims. We present comparisons of shock models with observations of H 2 and SiO emission in the bipolar outflow BHR71. Such comparisons constitute a good way to constrain the type, velocity and age of the shock waves operating in this environment, as well as the physical conditions in the pre-shock region, e.g. density and magnetic field. They also provide a method for studying silicon in shocked regions. We make use of all the preliminary physical constraints obtained through such comparisons to predict water emission, under the basic assumption that the emission regions of the considered species coincide, at the resolution of currently available observations. Methods. New SiO observations from APEX are presented, and combined with Spitzer and ground-based observations of H 2 to constrain shock models. The shock regions associated with targeted positions in the molecular outflow are studied by means of a code that generates one-dimensional models of the propagation of stationary shock waves, and approximations to non-stationary ones. The emission of H 2 is dealt with in the code, whereas the emission of SiO and H 2 O are calculated by means of an external module, based on the LVG approximation. This external code provides local and integrated intensities for the lines of these species. A grid of models is used, covering shock velocities in the range 10 ≤ s ≤ 35 km s −1 , and pre-shock gas densities 10 4 ≤ n H ≤ 10 6 cm −3 . The magnetic field strength varies from about 45 μG to 600 μG. Results. The SiO emission in the inner part of the outflow is concentrated near the apex of the corresponding bow-shock that is also seen in the pure rotational transitions of H 2 . Simultaneous modelling is possible for H 2 and SiO and leads to constraints on the silicon pre-shock distribution on the grain mantles and/or cores. The best-fitting models are found to be of the non-stationary type, but the degeneracy of the solutions is still large. Pre-shock densities of 10 4 and 10 5 cm −3 are investigated, and the associated best-model candidates have rather low velocity (respectively, 20−30 and 10−15 km s −1 ) and are not older than 1000 years. We provide emission predictions for water, focusing on the brightest transitions, to be observed with the PACS and HIFI instruments of the Herschel Telescope.

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Discovery of a Highly Collimated Molecular Outflow in the Southern Bok Globule BHR 71

Cited by 123 publications

References 44 publications

Impacts of pure shocks in the BHR71 bipolar outflow

Impacts of pure shocks in the BHR71 bipolar outflow

G30.79 FIR 10: a gravitationally bound infalling high-mass star-forming clump

Revisiting the shocks in BHR71: new observational constraints and H₂O predictions forHerschel

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Discovery of a Highly Collimated Molecular Outflow in the Southern Bok Globule BHR 71

Cited by 123 publications

References 44 publications

Impacts of pure shocks in the BHR71 bipolar outflow

Impacts of pure shocks in the BHR71 bipolar outflow

G30.79 FIR 10: a gravitationally bound infalling high-mass star-forming clump

Revisiting the shocks in BHR71: new observational constraints and H2O predictions forHerschel

Contact Info

Product

Resources

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Revisiting the shocks in BHR71: new observational constraints and H₂O predictions forHerschel