The clumpiness of molecular clouds: HCO<sup>+</sup>(3–2) survey near Herbig-Haro objects

Whyatt, W.; Girart, J. M.; Viti, S.; Estalella, R.; Williams, D. A.

doi:10.1051/0004-6361/20078350

Cited by 7 publications

(8 citation statements)

References 42 publications

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“…In the adapted model, the moving source of this radiation field (representing the HHO) passes the clump on a straight path with a minimum distance to the edge of the clump, here chosen to be 0.05 pc. This distance is similar to values found by Whyatt et al (2010) in an observational study of regions around 22 HHOs. For a source moving at 300 km s −1 , there will be enough time for it to reach closest approach (at around 1000 yr) and move some distance away before phase II is terminated.…”

Section: The Modelsupporting

confidence: 90%

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Chemistry of dense clumps near moving Herbig-Haro objects

Christie¹,

Viti²,

Williams³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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Localised regions of enhanced emission from HCO+, NH3 and other species near Herbig-Haro objects (HHOs) have been interpreted as arising in a photochemistry stimulated by the HHO radiation on high density quiescent clumps in molecular clouds. Static models of this process have been successful in accounting for the variety of molecular species arising ahead of the jet; however recent observations show that the enhanced molecular emission is widespread along the jet as well as ahead. Hence, a realistic model must take into account the movement of the radiation field past the clump. It was previously unclear as to whether the short interaction time between the clump and the HHO in a moving source model would allow molecules such as HCO+ to reach high enough levels, and to survive for long enough to be observed. In this work we model a moving radiation source that approaches and passes a clump. The chemical picture is qualitatively unchanged by the addition of the moving source, strengthening the idea that enhancements are due to evaporation of molecules from dust grains. In addition, in the case of several molecules, the enhanced emission regions are longer-lived. Some photochemically-induced species, including methanol, are expected to maintain high abundances for ~10,000 years.Comment: 7 pages, 3 figure

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Section: The Modelsupporting

confidence: 90%

“…This number density is observationally determined to be in the range 10 4 to 10 5 cm −3 (e.g. Girart et al 2005; Whyatt et al 2010). We have also explored the effect of allowing somewhat higher densities in several models (see Table 1).…”

Section: The Modelmentioning

confidence: 99%

Chemistry of dense clumps near moving Herbig-Haro objects

Christie¹,

Viti²,

Williams³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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“…These clumps do not show evidence for shock heating as indicated by their typically observed narrow linewidths (< 1 km s −1 ), low temperatures (< 20 K) and radial velocities close to the ambient cloud velocity (e.g. Whyatt et al 2010). All these properties rule out the possibility of a dynamical perturbation.…”

Section: Introductionmentioning

confidence: 85%

“…Claims for evidence of association of molecular clumps with HH objects have been growing over the last decades (Rudolph & Welch 1988;Davis, Dent & Bell Burnell 1990;Torrelles et al 1992Torrelles et al , 1993Girart et al 1994Girart et al , 1998Viti, Girart & Hatchell 2006;Whyatt et al 2010). These clumps do not show evidence for shock heating as indicated by their typically observed narrow linewidths (< 1 km s −1 ), low temperatures (< 20 K) and radial velocities close to the ambient cloud velocity (e.g.…”

Section: Introductionmentioning

confidence: 99%

A Multi-Wavelength Study of the Star-Forming Core Ahead of Hh 80n

Masqué

Osorio

Girart

et al. 2011

ApJ

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We present observations of continuum emission in the MIR to mm wavelength range, complemented with ammonia observations, of the dense core ahead of the radio Herbig Haro object HH 80N, found in the GGD 27 region. The continuum emission in all the observed bands peaks at the same position, consistent with the presence of an embedded object, HH 80N-IRS1, within the core. The distribution of the VLA ammonia emission is well correlated with that of the dust, suggesting that photochemical effects caused by the nearby Herbig Haro object do not play an important role in shaping this particular molecular emission. In order to unveil the nature of HH 80N-IRS1 we analyzed the continuum data of this source, using self-consistent models of protostellar collapse. We find that a young protostar surrounded by a slowly rotating collapsing envelope of radius ∼0.08 pc and 20 M ⊙ plus a circumstellar disk of radius ∼300 AU and 0.6 M ⊙ -2 -provide a good fit to the observed spectral energy distribution and to the maps at 350 µm, 1.2 mm and 3.5 mm of HH 80N-IRS1. Besides, the APEX and PdBI continuum maps at 350 µm and 3.5 mm, respectively, reveal additional clumps in the continuum emission. Given the modeling results and the observed morphology of the emission, we propose a scenario consisting of a central embedded Class 0 object, HH 80N-IRS1, with the rest of material of the HH 80N core possibly undergoing fragmentation that may lead to the formation of several protostars.

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“…The velocity shift detected could results from the interaction between the jet and the dense gas. Indeed, Whyatt et al (2009) find that the HH objects are illuminating the molecular gas, enhancing the emission of the HCO + associated with a dense molecular condensation within the ammonia core.…”

Section: A9 L1634mentioning

confidence: 99%

Dense gas and the nature of the outflows

Sepúlveda

Anglada

Estalella

et al. 2011

A&A

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We present the results of the observations of the (J, K) = (1, 1) and the (J, K) = (2, 2) inversion transitions of the NH 3 molecule toward a large sample of 40 regions with molecular or optical outflows, using the 37 m radio telescope of the Haystack Observatory. We detected NH 3 emission in 27 of the observed regions, which we mapped in 25 of them. Additionally, we searched for the 6 16 −5 23 H 2 O maser line toward six regions, detecting H 2 O maser emission in two of them, HH265 and AFGL 5173. We estimate the physical parameters of the regions mapped in NH 3 and analyze for each particular region the distribution of high density gas and its relationship with the presence of young stellar objects. In particular, we identify the deflecting high-density clump of the HH270/110 jet. We were able to separate the NH 3 emission from the L1641-S3 region into two overlapping clouds, one with signs of strong perturbation, probably associated with the driving source of the CO outflow, and a second, unperturbed clump, which is probably not associated with star formation. We systematically found that the position of the best candidate for the exciting source of the molecular outflow in each region is very close to an NH 3 emission peak. From the global analysis of our data we find that in general the highest values of the line width are obtained for the regions with the highest values of mass and kinetic temperature. We also found a correlation between the nonthermal line width and the bolometric luminosity of the sources, and between the mass of the core and the bolometric luminosity. We confirm with a larger sample of regions the conclusion of Anglada et al. (1997) that the NH 3 line emission is more intense toward molecular outflow sources than toward sources with optical outflow, suggesting a possible evolutionary scheme in which young stellar objects associated with molecular outflows progressively lose their neighboring high-density gas, weakening both the NH 3 emission and the molecular outflow in the process, and making optical jets more easily detectable as the total amount of gas decreases.

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The clumpiness of molecular clouds: HCO⁺(3–2) survey near Herbig-Haro objects

Cited by 7 publications

References 42 publications

Chemistry of dense clumps near moving Herbig-Haro objects

Chemistry of dense clumps near moving Herbig-Haro objects

A Multi-Wavelength Study of the Star-Forming Core Ahead of Hh 80n

Dense gas and the nature of the outflows

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The clumpiness of molecular clouds: HCO+(3–2) survey near Herbig-Haro objects

Cited by 7 publications

References 42 publications

Chemistry of dense clumps near moving Herbig-Haro objects

Chemistry of dense clumps near moving Herbig-Haro objects

A Multi-Wavelength Study of the Star-Forming Core Ahead of Hh 80n

Dense gas and the nature of the outflows

Contact Info

Product

Resources

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The clumpiness of molecular clouds: HCO⁺(3–2) survey near Herbig-Haro objects