Laboratory Analog of Heavy Jets Impacting a Denser Medium in Herbig–Haro (HH) Objects

2018 ◽  
Vol 868 (1) ◽  
pp. 56 ◽  
Author(s):  
G. Y. Liang ◽  
J. Y. Zhong ◽  
H. G. Wei ◽  
D. W. Yuan ◽  
Z. Zhang ◽  
...  
Keyword(s):  
Hh Objects ◽  
Laboratory Analog

scholarly journals Far-IR Spectrophotometry of HH Flows with the ISO Long-Wavelength Spectrometer

1997 ◽  
Vol 182 ◽  
pp. 111-120
Author(s):  
R. Liseau ◽  
T. Giannini ◽  
B. Nisini ◽  
P. Saraceno ◽  
L. Spinoglio ◽  
...  
Keyword(s):  
Mass Loss ◽  
Line Emission ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Star Forming ◽  
Star Forming Regions ◽  
Shock Models ◽  
Ir Spectrophotometry ◽  
Hh Objects ◽  
Loss Rates

Full Iso-Lws spectral scans between about 45 to 190 μm of 17 individual HH objects in 7 star forming regions have revealed essentially only [O I] 63 μm line emission, implying that the Fircooling of these objects is totally dominated by this line alone. In this case, J-shock models can be used to determine the mass loss rates of the HH exciting sources. These mass loss rates are in reasonably good agreement with those estimated for the accompanying CO flows, providing first observational evidence that HH and molecular flows are driven by the same agent. The Lmech – Lbol relation, based on our results with the Lws, implies that young stellar objects of lower mass are loosing mass at relatively higher rates than their more massive counterparts.

scholarly journals The Molecular Outflow and CO Bullets in HH111

1997 ◽  
Vol 182 ◽  
pp. 141-152 ◽  
Author(s):  
J. Cernicharo ◽  
R. Neri ◽  
Bo Reipurth
Keyword(s):  
High Velocity ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Low Velocity ◽  
Molecular Outflow ◽  
Hh Objects ◽  
Physical Phenomena ◽  
First Time

We present high angular resolution observations of the molecular outflow associated with the optical jet and HH objects of the HH111 system. Interferometric observations in the CO J =2–1 and J =1–0 lines of the high velocity bullets associated with HH111 are presented for the first time. The molecular gas in these high velocity clumps has a moderate kinetic temperature and a mass of a few 10–4 M⊙ per bullet. We favor the view that HH jets and CO bullets, which represent different manifestations of the same physical phenomena, are driving the low-velocity molecular outflow.

scholarly journals The Structure of the HH39 Region

1987 ◽  
Vol 115 ◽  
pp. 340-341
Author(s):  
J. R. Walsh
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Proper Motion ◽  
High Velocity ◽  
Velocity Structure ◽  
The Other ◽  
Emission Lines ◽  
High Resolution Spectroscopy ◽  
Bow Shocks ◽  
Hh Objects

HH39 is the group of Herbig-Haro (HH) objects associated with the young semi-stellar object R Monocerotis (R Mon) and the variable reflection nebula NGC 2261. An R CCD frame and a B prime focus plate of the region show a filament connecting NGC 2261 with HH39, confirming the association between R Mon and the HH objects. This filament is probably composed of emission material. The southern knot in HH39 has brightened over the last 20 years; its proper motion has been determined and is similar to that of the other knots. A total of 8 knots can be distinguished in HH39 surrounded by diffuse nebulosity. High resolution spectroscopy of the Hα and [N II] emission lines shows the spatial variation of the radial velocity structure over the largest knots (HH39 A and C). Distinct differences in excitation and velocity structure between the knots are apparent. The observations are compatible with the knots being high velocity ejecta from R Mon, decelerated by interaction with ambient material and with bow shocks on their front surfaces.

scholarly journals Filtered CCD images of southern Herbig-Haro objects

1987 ◽  
Vol 122 ◽  
pp. 189-190
Author(s):  
B. Whitmore ◽  
D.H.M. Cameron ◽  
R.F. Warren-Smith
Keyword(s):  
High Velocity ◽  
Optical Emission ◽  
Emission Lines ◽  
Ccd Cameras ◽  
Hh Objects

It is currently believed that Herbig-Haro (HH) objects are a consequence of a high-velocity (up to at least 200 km s−1) outflow of material from a young embedded star. These flows can often be detected by deep observations of optical emission lines using CCD cameras.

scholarly journals Jet Interactions with Molecular Clouds: C–Shock Models

1990 ◽  
Vol 140 ◽  
pp. 332-332
Author(s):  
M.D. Smith ◽  
P.W.J.L. Brand
Keyword(s):  
Young Stellar Objects ◽  
Stellar Objects ◽  
Hydrogen Emission ◽  
Shock Models ◽  
Hydrogen Emission Lines ◽  
Bow Shocks ◽  
Hh Objects ◽  
Jet Interactions ◽  
Model Context ◽  
The Magnetic Field

Molecular hydrogen emission lines are associated with collimated outflows from young stellar objects. They have been measured near Herbig–Haro objects within jets as well as at the jet termination. Similarly to HH objects, the lines are produced from radiative shocks which may be in the form of oblique internal jet shocks or bow shocks. A J-shock can only be invoked in a dynamical model context since the H2 lines are often wide (> 30 km s−1). The alternative is the MHD C–shock in which the ionisation level is sufficiently low so that the magnetic field and ions interact weakly with the neutrals. We have investigated C-shock flows by employing approximate forms for the ion-neutral drag, cooling and other processes with the following results.

scholarly journals Models for the Emission-Line Spectra of the Low-Excitation Herbig-Haro Objects

1987 ◽  
Vol 115 ◽  
pp. 346-347
Author(s):  
Michael A. Dopita ◽  
Saul Caganoff ◽  
Richard D. Schwartz ◽  
Martin Cohen
Keyword(s):  
Emission Line ◽  
Theoretical Description ◽  
Line Spectrum ◽  
High Excitation ◽  
Two Photon ◽  
Shock Models ◽  
Uv Excess ◽  
Hh Objects ◽  
Emission Line Spectrum

The class of Low-Excitation Herbig-Haro Objects are characterised by [SII] and [OI] lines which are comparable in strength to H-Alpha, by [NI] lines that are comparable to H-Beta, relatively weak [NII] and [OII] lines, little or no [OIII] emission and a very strong blue-UV “excess”. This blue and UV continuum in low-excitation HH Objects was noted as a problem by Brugel, Böhm and Mannery (1981), Ortalani and D'Odorico (1980) and Böhm, Böhm-Vitense and Brugel (1981). The first suggestion that it results from collisionally enhanced Hydrogen two-photon (2q) continuum was by Dopita (1981). The subsequent observations of Dopita, Binette and Schwartz (1982) proved that this was indeed the case. However, although very close correlations between this enhancement and the emission-line spectrum were found, a fair theoretical description could only be obtained for very youthful shock models with ages of order 30 years. However, there seems to be no reason why low excitation HH shocks should be much younger than the high excitation shocks.

Sign in / Sign up

Export Citation Format

Share Document