Oxygen budget in low-mass protostars: the NGC 1333-IRAS4A R1 shock observed in [O i] at 63<i>μ</i>m with SOFIA-GREAT

Kristensen, L. E.; Gusdorf, A.; Mottram, J. C.; Karska, A.; Visser, R.; Wiesemeyer, H.; Güsten, R.; Simon, R.

doi:10.1051/0004-6361/201630310

Cited by 24 publications

(30 citation statements)

References 29 publications

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“…We extracted the same spectra and ratio from two other star-forming regions. The first is the R1 shock spot of the NGC1333-IRAS4A bipolar outflow, which is driven by a low-mass protostar (for which r = 0.011 pc, d = 235 pc, L = 9.1 L ; Kristensen et al 2017). In this region, the [OI] 63 µm filling factor is of the order of unity, as shown by the half-maximum contour of Fig.…”

Section: Comparison With Other Star-forming Regionsmentioning

confidence: 95%

“…This source is an intermediate-mass Class 0 protostar (L = 100 L , Lefloch et al 1996;Chini et al 2001) in the Cepheus OB3 association at a distance of 730 pc (Sargent 1977). Its prominent and well-studied outflow is driven by a jet of a size of 1.7 × 21 , as identified in several CO transitions (Gómez-Ruiz et al 2012) up to and interpreted by means of time-dependent MHD shock models by hereafter L15).…”

Section: Introductionmentioning

confidence: 93%

“…The spectra of the -a narrow jet emitting between −140 and −110, centred on −125 km s −1 , with a typical line width of 15 km s −1 , well separated from the bipolar outflow wing emission; -the outflow cavity, composed of the gas contained in the cavity walls, that is, of the cavity walls plus the entrained gas that is not part of the jet that is emitted from the ambient cloud velocity (−10.9 km s −1 , Lefloch et al 1996) up to −100 km s −1 ; -the terminal bow-shock labelled 'HH377', which is emitted between −90 and −50 km s −1 and appears as a bump between the outflow cavity and the jet in the line profile, and whose intensity is similar to the entrained gas at −20 km s −1 .…”

Section: Line Profilesmentioning

confidence: 99%

“…This value has then to be corrected for the absorption by dust grains. We assumed an average local density in the outflow cavity of 10 −4 cm −3 , which translates into a column density of N H 2.6×10 21 cm −2 and into a visual extinction of A v 1.4 mag (Lefloch et al 1996 provided local estimates for this value: 61 mag around the driving protostar, and 3.2-3.4 mag in the H 2 knots along the flow). Using the exponential attenuation approximation I = I 0 × e −τ , where τ = N H × σ, and σ is the effective attenuation cross section from Draine & Bertoldi (1996), we found that the radiation field really felt in BII is about 2.6 × 10 −3 G 0 in Draine's or Mathis's ISRF units.…”

Section: Shock Modelling Of the Jet Componentmentioning

confidence: 99%

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Nature of shocks revealed by SOFIA OI observations in the Cepheus E protostellar outflow

Gusdorf

Anderl

Leflóch

et al. 2017

A&A

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Context. Protostellar jets and outflows are key features of the star-formation process, and primary processes of the feedback of young stars on the interstellar medium. Understanding the underlying shocks is necessary to explain how jet and outflow systems are launched, and to quantify their chemical and energetic impacts on the surrounding medium. Aims. We performed a high-spectral resolution study of the [OI] 63 µm emission in the outflow of the intermediate-mass Class 0 protostar Cep E-mm. The goal is to determine the structure of the outflow, to constrain the chemical conditions in the various components, and to understand the nature of the underlying shocks, thus probing the origin of the mass-loss phenomenon.Methods. We present observations of the O i 3 P 1 → 3 P 2 , OH between 2 Π 1/2 J = 3/2 and J = 1/2 at 1837.8 GHz, and CO (16-15) lines with the GREAT receiver onboard SOFIA towards three positions in the Cep E protostellar outflow: Cep E-mm (the driving protostar), Cep E-BI (in the southern lobe), and Cep E-BII (the terminal position in the southern lobe). Results. The line is detected at all three positions. The [OI] 63 µm line is detected in Cep E-BI and BII, whereas the OH line is not detected. In Cep E-BII, we identify three kinematical components in O i and CO. These were already detected in CO transitions and relate to spatial components: the jet, the HH377 terminal bow-shock, and the outflow cavity. We measure line temperature and line integrated intensity ratios for all components. The O i column density is higher in the outflow cavity than in the jet, which itself is higher than in the terminal shock. The terminal shock is the region where the abundance ratio of O i to CO is the lowest (about 0.2), whereas the jet component is atomic (N(O i) / N(CO) ∼ 2.7). In the jet, we compare the [OI] 63 µm observations with shock models that successfully fit the integrated intensity of 10 CO lines. We find that these models most likely do not fit the [OI] 63 µm data.Conclusions. The high intensity of O i emission points towards the propagation of additional dissociative or alternative FUV-irradiated shocks, where the illumination comes from the shock itself. A picture emerges from the sample of low-to-high mass protostellar outflows, where similar observations have been performed, with the effects of illumination increasing with the mass of the protostar. These findings need confirmation with more observational constraints and a larger sample.

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Section: Comparison With Other Star-forming Regionsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 93%

Section: Line Profilesmentioning

confidence: 99%

Section: Shock Modelling Of the Jet Componentmentioning

confidence: 99%

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Nature of shocks revealed by SOFIA OI observations in the Cepheus E protostellar outflow

Gusdorf

Anderl

Leflóch

et al. 2017

A&A

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“…10 The reliability of this tuning mechanism is demonstrated by numerous observations based on the 63 lm emission line of oxygen from several astronomical objects. [22][23][24][25] Furthermore, various approaches to gas sensing in the THz spectral region are based on intrinsic tuning due to changes of the applied current. 5,6,26,27 Similarly, the recently introduced wideband, gapless sources 11 rely on changes of both, the current density and the operating temperature of the active region, during the current ramps.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic frequency tuning of terahertz quantum-cascade lasers

Schrottke

Lü

Röben

et al. 2018

Journal of Applied Physics

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We have studied the intrinsic frequency tuning of several terahertz (THz) quantum-cascade lasers (QCLs) based on a hybrid design. With increasing driving current, most QCLs exhibit either a redshift or a blueshift, while some QCLs show both. An oscillator model describes the observed behavior. The accuracy of the model is affected by the complexity of the current-dependent gain spectra of the THz QCLs. Numerical simulations demonstrate a cavity pulling effect insofar as the tuning behavior depends on the resonator losses and on the width of the gain spectra.

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Herschel observations of the circumstellar environments of the Herbig Be stars R Mon and PDS 27

Jiménez-Donaire

Meeus

Karska

et al. 2017

A&A

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Context. The circumstellar environment of Herbig Be stars in the far-infrared is poorly characterised, mainly because they are often embedded and rather distant. The analysis of far-infrared spectroscopy allows us to make a major step forward by covering multiple rotational lines of molecules, e.g. CO, that are useful probes of physical conditions of the gas. Aims. To characterise the gas and dust in the disc and environment of Herbig Be stars, and to compare the results with those of their lower-mass counterparts, the Herbig Ae stars. Methods. We report and analyse far-infrared observations of two Herbig Be stars, R Mon and PDS 27, obtained with Herschel's instruments PACS and SPIRE. We construct spectral energy distributions and derive the infrared excess. We extract line fluxes from the PACS and SPIRE spectra and construct rotational diagrams in order to estimate the excitation temperature of the gas. We derive CO, [O I] and [C I] luminosities to determine physical conditions of the gas, as well as the dominant cooling mechanism. Results. We confirm that the Herbig Be stars are surrounded by remnants from their parental clouds, with an IR excess that mainly originates in a disc. In R Mon we detect [O I], [C I], [C II], CO (26 transitions), water and OH, while in PDS 27 we only detect [C I] and CO (8 transitions). We attribute the absence of OH and water in PDS 27 to UV photo-dissociation and photo-evaporation. From the rotational diagrams, we find several components for CO: we derive T rot 949±90 K, 358±20 K & 77±12 K for R Mon, 96±12 K & 31±4 K for PDS 27 and 25±8 K & 27±6 K for their respective compact neighbours. The forsterite feature at 69 µm was not detected in either of the sources, probably due to the lack of (warm) crystalline dust in a flat disc. We find that cooling by molecules is dominant in the Herbig Be stars, while this is not the case in Herbig Ae stars where cooling by [O I] dominates. Moreover, we show that in the Herbig Be star R Mon, outflow shocks are the dominant gas heating mechanism, while in Herbig Ae stars this is stellar. Conclusions. The outflow of R Mon contributes to the observed line emission by heating the gas, both in the central spaxel/beam covering the disc and the immediate surroundings, as well as in those spaxels/beams covering the parabolic shell around it. PDS 27, a B2 star, has dispersed a large part of its gas content and/or destroyed molecules; this is likely given its intense UV field.

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Oxygen budget in low-mass protostars: the NGC 1333-IRAS4A R1 shock observed in [O i] at 63μm with SOFIA-GREAT

Cited by 24 publications

References 29 publications

Nature of shocks revealed by SOFIA OI observations in the Cepheus E protostellar outflow

Nature of shocks revealed by SOFIA OI observations in the Cepheus E protostellar outflow

Intrinsic frequency tuning of terahertz quantum-cascade lasers

Herschel observations of the circumstellar environments of the Herbig Be stars R Mon and PDS 27

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