Structure and proper motions in Herbig-Haro objects 1 and 2

Eislöffel, J.; Mundt, R.; Bohm, Karl‐Heinz

doi:10.1086/117133

Cited by 78 publications

(76 citation statements)

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“…The physical structure of the HH 1 jets and its terminal bows has been previously analysed by Solf & Böhm (1991), Nisini et al (2005), and Böhm & Solf (1985), Solf et al (1988), Eislöffel et al (1994), Bally et al (2002). In our observations the slit is aligned along the jet and it covers the fainter western/eastern parts of HH 1 and HH 2 respectively, i.e.…”

Section: Appendix A: Physical Structure Of Previously Analysed Jetsmentioning

confidence: 59%

Physical structure and dust reprocessing in a sample of HH jets

Podio

Medves

Bacciotti

et al. 2009

A&A

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Context. Stellar jets are an essential ingredient of the star formation process and a wealth of information can be derived from their characteristic emission-line spectra. Aims. We investigate the physical structure and dust reprocessing in the shocks along the beam of a number of classical Herbig-Haro (HH) jets in the Orion and Lupus molecular clouds (HH 111, HH 1/2, HH 83, HH 24 M/A/E/C, and Sz68). Parameters describing plasma conditions, as well as dust content, are derived as a function of distance from the source and, for HH 111, of gas velocity. Methods. Spectral diagnostic techniques are applied to obtain the jet physical conditions (the electron and total density, n e and n H , the ionisation fraction, x e , and the temperature, T e ) from the ratios of selected forbidden lines. The presence of dust grains is investigated by estimating the gas-phase abundance of calcium with respect to its solar value. Results. We find the electron density varies between 0.05-4 × 10 3 cm −3 , the ionisation fraction x e from 0.01-0.7, the temperature ranges between 0.6-3 × 10 4 K, and the hydrogen density between 0.01-6 × 10 4 cm −3 . Interestingly, in the HH 111 jet, n e , x e , and T e peak in the high velocity interval (HVI) of the strongest working surfaces, confirming a prediction from shocks models. Calcium turns out to be depleted with respect to its solar value, but its gas-phase abundance is higher than estimates for the interstellar medium in Orion. The depletion is high (up to 80%) along the low-excited jets, while low or no depletion is measured in those jets which show higher excitation conditions. Moreover, for HH 111 the depletion is lower in the HVI of the fastest shock. Conclusions. Our results confirm the shock structure predicted by models and indicate that shocks occurring along jets, and presumably those present in the launch zone, only partially destroy dust grains and that the efficiency of dust reprocessing strongly depends on shock velocity. However, the high Ca gas-phase abundance estimated in some of the knots, is not well understood in terms of existing models of dust reprocessing in shocks, and indicates that the dust must have been partially reprocessed in the region where the flow originates.

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Section: Appendix A: Physical Structure Of Previously Analysed Jetsmentioning

confidence: 59%

Physical structure and dust reprocessing in a sample of HH jets

Podio

Medves

Bacciotti

et al. 2009

A&A

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“…Outflows sweep away part of the parent envelope of the star and shock-excite the ambient molecular gas as they propagate from the star. Down the axis of jets, shocks are often observed as bowshaped structures (e.g., Eislöffel et al 1994;Reipurth & Bally 2001;Nissen et al 2007;Davis et al 2009), which suggests that they form from deflected gas around the leading head of the jet. The shock excitation of the surrounding cloud induces line emission that is characteristic of the physical and chemical environments and the velocity of the impact (Kristensen et al 2007).…”

Section: Introductionmentioning

confidence: 99%

3D model of bow shocks

Gustafsson¹,

Ravkilde

Kristensen

et al. 2010

A&A

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Context. Shocks produced by outflows from young stars are often observed as bow-shaped structures in which the H 2 line strength and morphology are characteristic of the physical and chemical environments and the velocity of the impact. Aims. We present a 3D model of interstellar bow shocks propagating in a homogeneous molecular medium with a uniform magnetic field. The model enables us to estimate the shock conditions in observed flows. As an example, we show how the model can reproduce rovibrational H 2 observations of a bow shock in OMC1.Methods. The 3D model is constructed by associating a planar shock with every point on a 3D bow skeleton. The planar shocks are modelled with a highly sophisticated chemical reaction network that is essential for predicting accurate shock widths and line emissions. The shock conditions vary along the bow surface and determine the shock type, the local thickness, and brightness of the bow shell. The motion of the cooling gas parallel to the bow surface is also considered. The bow shock can move at an arbitrary inclination to the magnetic field and to the observer, and we model the projected morphology and radial velocity distribution in the plane-of-sky. Results. The morphology of a bow shock is highly dependent on the orientation of the magnetic field and the inclination of the flow. Bow shocks can appear in many different guises and do not necessarily show a characteristic bow shape. The ratio of the H 2 v = 2−1 S(1) line to the v = 1−0 S(1) line is variable across the flow and the spatial offset between the peaks of the lines may be used to estimate the inclination of the flow. The radial velocity comes to a maximum behind the apparent apex of the bow shock when the flow is seen at an inclination different from face-on. Under certain circumstances the radial velocity of an expanding bow shock can show the same signatures as a rotating flow. In this case a velocity gradient perpendicular to the outflow direction is a projection effect of an expanding bow shock lighting up asymmetrically because of the orientation of the magnetic field. With the 3D model we reproduce the brightness levels in three H 2 lines as well as the shape and size of a chosen bow shock in OMC1. The inferred bow inclination and the orientation and strength of the magnetic field fit into the pattern suggested by independent observations.

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“…HH 147 MMS is the dense core containing N 3 SK 50, the driving source of the HH 147 outflow (Nakajima et al 1986;Eislöffel et al 1994;Chini et al 1997Chini et al , 2001Choi & Zhou 1997). The nature of this YSO is unclear.…”

Section: Appendix Individual Dense Coresmentioning

confidence: 99%

“…HH 1-2 MMS 1 HH 1-2 MMS 1 is the dense core containing the driving source of the archetypal Herbig-Haro objects HH 1 and HH 2 (Chini et al 1997(Chini et al , 2001). The optical jet, HH objects, and their environment have been studied extensively (Strom et al 1989;Reipurth et al 1993;Eislöffel et al 1994;Corcoran & Ray 1995;Kwon et al 2010). There are three compact sources, VLA 1/2/4, detected in centimeter continuum (Rodríguez et al 2000).…”

Section: Appendix Individual Dense Coresmentioning

confidence: 99%

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Stacked Average Far-infrared Spectrum of Dusty Star-forming Galaxies from the Herschel/SPIRE Fourier Transform Spectrometer^∗

Wilson

Cooray

Nayyeri

et al. 2017

ApJ

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The V380 Ori NE bipolar outflow was imaged in the SiO and CO =  J 1 0 lines, and dense cores in L1641 were observed in the 2.0-0.89 mm continuum. The highly collimated SiO jet shows point-symmetric oscillation patterns in both position and velocity, which suggests that the jet axis is precessing and the driving source may belong to a non-coplanar binary system. By considering the position and velocity variabilities together, accurate jet parameters were derived. The protostellar system is viewed nearly edge-on, and the jet has a flow speed of ∼35 km s −1 and a precession period of ∼1600 years. The CO outflow length gives a dynamical timescale of ∼6300 years, and the protostar must be extremely young. The inferred binary separation of 6-70 au implies that this protobinary system may have been formed through the disk instability process. The continuum spectra of L1641 dense cores indicate that the emission comes from dust, and the fits with modified blackbody functions give emissivity power indices of β=0.3-2.2. The emissivity index shows a positive correlation with the molecular line width, but no strong correlation with bolometric luminosity or temperature. V380 Ori NE has a particularly low value of β=0.3, which tentatively suggests the presence of millimeter-sized dust grains. Because the dust growth takes millions of years, much longer than the protostellar age, this core may have produced large grains in the starless core stage. HH 34 MMS and HH 147 MMS also have low emissivity indices.

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Structure and proper motions in Herbig-Haro objects 1 and 2

Cited by 78 publications

References 0 publications

Physical structure and dust reprocessing in a sample of HH jets

Physical structure and dust reprocessing in a sample of HH jets

3D model of bow shocks

Stacked Average Far-infrared Spectrum of Dusty Star-forming Galaxies from the Herschel/SPIRE Fourier Transform Spectrometer^∗

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Structure and proper motions in Herbig-Haro objects 1 and 2

Cited by 78 publications

References 0 publications

Physical structure and dust reprocessing in a sample of HH jets

Physical structure and dust reprocessing in a sample of HH jets

3D model of bow shocks

Stacked Average Far-infrared Spectrum of Dusty Star-forming Galaxies from the Herschel/SPIRE Fourier Transform Spectrometer∗

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Product

Resources

About

Stacked Average Far-infrared Spectrum of Dusty Star-forming Galaxies from the Herschel/SPIRE Fourier Transform Spectrometer^∗