Chemistry of dense clumps near moving Herbig-Haro objects

Christie, H.; Viti, S.; Williams, D. A.; Girart, J. M.; Morata, Ó.

doi:10.1111/j.1365-2966.2011.19032.x

Cited by 3 publications

(5 citation statements)

References 16 publications

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“…findings are consistent with many other observational and theoretical studies that have seen enhanced chemistry in the vicinity of shocked, irradiated gas (e.g., in HH objects: Girart et al 1994;Taylor & Williams 1996;Viti & Williams 1999;Girart et al 2002;Christie et al 2011). CO (J = 6 → 5) was detected in observations of BHR 71 with the Atacama Pathfinder EXperiment (APEX) telescope by van Kempen et al (2009b) and Gusdorf et al (2015); the observations by Gusdorf et al resolve this high-J CO emission in both the IRS1 and IRS2 outflows.…”

Section: Irradiation Of the Outflow Cavity Walls In Bhr 71supporting

confidence: 92%

Understanding the Origin of the Magnetic Field Morphology in the Wide-binary Protostellar System BHR 71

Hull

Gouellec

Girart

et al. 2020

ApJ

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We present 1.3 mm ALMA observations of polarized dust emission toward the wide-binary protostellar system BHR 71 IRS1 and IRS2. IRS1 features what appears to be a natal, hourglass-shaped magnetic field. In contrast, IRS2 exhibits a magnetic field that has been affected by its bipolar outflow. Toward IRS2, the polarization is confined mainly to the outflow cavity walls. Along the northern edge of the redshifted outflow cavity of IRS2, the polarized emission is sandwiched between the outflow and a filament of cold, dense gas traced by N 2 D + , toward which no dust polarization is detected. This suggests that the origin of the enhanced polarization in IRS2 is the irradiation of the outflow cavity walls, which enables the alignment of dust grains with respect to the magnetic field-but only to a depth of ∼ 300 au, beyond which the dust is cold and unpolarized. However, in order to align grains deep enough in the cavity walls, and to produce the high polarization fraction seen in IRS2, the aligning photons are likely to be in the mid-to far-infrared range, which suggests a degree of grain growth beyond what is typically expected in very young, Class 0 sources. Finally, toward IRS1 we see a narrow, linear feature with a high (10-20%) polarization fraction and a well ordered magnetic field that is not associated with the bipolar outflow cavity. We speculate that this feature may be a magnetized accretion streamer; however, this has yet to be confirmed by kinematic observations of dense-gas tracers. T19 discussed the formation conditions of BHR 71 at length, using both new and archival data to analyze the kinematics and continuum properties across a wide range of spatial scales ranging from ∼ 0.5 pc -80 au. They presented J-band near-infrared (NIR) observations from the

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Section: Irradiation Of the Outflow Cavity Walls In Bhr 71supporting

confidence: 92%

Understanding the Origin of the Magnetic Field Morphology in the Wide-binary Protostellar System BHR 71

Hull

Gouellec

Girart

et al. 2020

ApJ

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“…We conducted the JCMT HCO + (4-3) and HCN (4-3) observations to test the idea that NH 3 −S is externally illuminated by UV radiation from the Herbig-Haro objects. Observations of externally illuminated clumps show that the HCO + emission is enhanced in these regions with line intensities much stronger than expected in quiescent dark clouds, which was successfully explained by theoretical models (see above; e.g., Taylor & Williams 1996;Viti & Williams 1999;Girart et al 2002;Viti et al 2003;Christie et al 2011). HCN is expected to be underabundant (e.g., Girart et al 2002).…”

Section: Hco + and Hcnmentioning

confidence: 54%

“…(Boogert et al 2015) and drive an active gas-phase pho-tochemistry. This interpretation is supported by both observations and theoretical models (both static and dynamic where the radiation source is moving; Taylor & Williams 1996;Christie et al 2011). The classical examples of externally illuminated clumps are those found near HH 1/2 (e.g., Girart et al 2002), HH 7-11 (e.g., Dent et al 1993), HH 34 (e.g., Rudolph & Welch 1992, and HH 80N (e.g., Girart et al 1994Girart et al , 1998Girart et al , 2001.…”

Section: External Illuminationmentioning

confidence: 79%

“…The high intensity of the NH 3 emission from NH 3 −S suggests that the source may also be affected by the strong UV radiation from HH 111 and HH 121 jets. Observational surveys have detected compact regions of enhanced emission (compared to quiescent dark clouds) in several molecules, among them NH 3 and HCO + , just ahead of Herbig-Haro objects (e.g., Torrelles et al 1992;Girart et al 1994;Girart et al 1998), as well as along the jets (e.g., Christie et al 2011). These "externally illuminated clumps" are quiescent, cool (∼10-20 K), have sizes of 10 -20 (0.019-0.038 pc at 400 pc), and have similar chemical properties.…”

Section: External Illuminationmentioning

confidence: 99%

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Very Large Array Ammonia Observations of the HH 111/HH 121 Protostellar System: A Detection of a New Source with a Peculiar Chemistry

Sewiło

Wiseman

Indebetouw

et al. 2017

ApJ

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We present the results of Very Large Array NH 3 (J, K) = (1, 1) and (2, 2) observations of the HH 111/HH 121 protostellar system. HH 111, with a spectacular collimated optical jet, is one of the most well-known Herbig-Haro objects. We report the detection of a new source (NH 3 −S) in the vicinity of HH 111/HH 121 (∼0.03 pc from the HH 111 jet source) in two epochs of the ammonia observations. This constitutes the first detection of this source, in a region which has been thoroughly covered previously by both continuum and spectral line interferometric observations. We study the kinematic and physical properties of HH 111 and the newly discovered NH 3 −S. We also use HCO + and HCN (J = 4 − 3) data obtained with the James Clerk Maxwell Telescope and archival Atacama Large Millimeter/submillimeter Array 13 CO, 12 CO, and C 18 O (J = 2 − 1), N 2 D + (J = 3 − 2), and 13 CS (J = 5 − 4) data to gain insight into the nature of NH 3 −S. The chemical structure of NH 3 −S shows evidence for "selective freeze-out", an inherent characteristic of dense cold cores. The inner part of NH 3 −S shows subsonic non-thermal velocity dispersions indicating a "coherent core", while they increase in the direction of the jets. Archival near-to far-infrared data show no indication of any embedded source in NH 3 −S. The properties of NH 3 −S and its location in the infrared dark cloud suggest that it is a starless core located in a turbulent medium with turbulence induced by Herbig-Haro jets and associated outflows. More data is needed to fully understand the physical and chemical properties of NH 3 −S and if/how its evolution is affected by nearby jets.

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“…The feedback from the star formation processes, which c 0000 RAS eventually disrupt the dense cores from which stars form, will also limit the growth of ice mantles or force the return of the adsorbed species to the gas phase, in a sporadic or intermittent manner, through a variety of mechanisms: by sublimation of icy mantles from warm grains near bright stars in a more or less gradual way (Viti & Williams 1999;Schöier et al 2002;Rodgers & Charnley 2003;Garrod et al 2008), by destruction or sputtering of grain cores and mantles by passing shocks (Charnley et al 1988;Flower & Pineau des Forets 1994;Bergin et al 1998;van Dishoeck & Blake 1998), or by ice sublimation due to UV radiation originating in shocks (Viti et al 2003;Christie et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Effects of H2 coating of grains on depletion of molecular species

Morata

Hasegawa

2013

Monthly Notices of the Royal Astronomical Society

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Physical conditions in dense and cold regions of interstellar clouds favour the formation of ice mantles on the surfaces of interstellar grains. It is predicted that most of the gaseous species heavier than H 2 or He will adsorb onto the grains and will disappear from the gas-phase, changing its chemistry, within ∼ 10 9 /n H years. Nonetheless, many molecules in molecular clouds are not completely depleted in timescales of 10 5 yr. Several speculative mechanisms have been proposed to explain why molecules stay in the gas phase, but up to now none are fully convincing. At the same time, these mechanisms are not mutually exclusive and we can still explore the effects of other possible processes. We speculate on the consequences of H 2 coating of grains on the evaporation rates of adsorbed species. More experiments and simulations are needed to calculate the evaporation rate E evap (X-H 2 ).

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Chemistry of dense clumps near moving Herbig-Haro objects

Cited by 3 publications

References 16 publications

Understanding the Origin of the Magnetic Field Morphology in the Wide-binary Protostellar System BHR 71

Understanding the Origin of the Magnetic Field Morphology in the Wide-binary Protostellar System BHR 71

Very Large Array Ammonia Observations of the HH 111/HH 121 Protostellar System: A Detection of a New Source with a Peculiar Chemistry

Effects of H2 coating of grains on depletion of molecular species

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