scholarly journals The Nature of the High Velocity Flow in CRL 618

1993 ◽  
Vol 155 ◽  
pp. 347-347
Author(s):  
R. Neri ◽  
M. Guélin ◽  
S. Guilloteau ◽  
R. Lucas ◽  
S. Garcia-Burillo ◽  
...  
Keyword(s):  
High Velocity ◽  
Planetary Nebula ◽  
Line Emission ◽  
Molecular Flow ◽  
Stellar Winds ◽  
Circumstellar Envelope ◽  
Hii Region ◽  
Molecular Outflow ◽  
Neutral Gas ◽  
Velocity Flow

Using the IRAM interferometer, we have mapped with a 2″.4 = 3″.4 resolution the J = 1 → 0 HCN line emission in the proto–planetary nebula CRL 618. Our maps resolve the 200 kms−1 molecular outflow (Cernicharo et al. 1989), as well as the slowly expanding circumstellar envelope (Bujarrabal et al. 1988), allowing a very precise positioning (≤ 0″.1) of these components with respect to the central HII region. 70% of the HCN envelope emission comes from a very compact, spherically symmetric core of size ≃ 3″.2. The core surrounds the high velocity gas which appears localized in a number of small ‘clumps’ (≤ 0″.5) – see figure. The large range of velocities observed in the ‘clumps’ suggests that we are not observing a decelerating molecular flow, but the impacts of a bipolar outflow on the slowly moving core, close to the HII region. The collision of a neutral gas outflow with high density regions (the ‘clumps’) results in the generation of dissociative shock-waves pushing and tearing the inner surface of the envelope. CRL 618 appears to have reached the stage where the stellar winds begin to disrupt and to scrape through the massive envelope, shortly before it evolves towards a Planetary Nebula.

scholarly journals High Velocity Flow Suggested by Wing Components of the Hα Line Profiles in the Selected Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 539-540
Author(s):  
S. Tamura ◽  
M. Otsuka ◽  
A. Tajitsu
Keyword(s):  
High Velocity ◽  
Gas Flow ◽  
Planetary Nebulae ◽  
Gas Flows ◽  
Stellar Winds ◽  
Short Report ◽  
Line Profiles ◽  
Internal Motions ◽  
Velocity Flow ◽  
Gaussian Method

This is a short report on the study of internal motions of selected Planetary nebulae. We have studied this subject with both high (4 or 8 Å/mm) and intermediate (20 Å/mm) dispersion spectrographs. During the course of this work we noticed the existence of a high velocity gas flow distinct from the well known expanding gas, but with smaller velocities than stellar winds (Yadoumaru & Tamura 1994 on Abell 30; Otsuka & Tamura, 2001 on H 4-1). We present subsequent results obtained with the intermediate dispersion spectrograph about 10 selected planetary nebulae. The analyses were made by multiple Gaussian method on the emission line profiles of Hα. High velocity gas flows were recognized by a weak broad wing component.

scholarly journals Extreme gas kinematics in an off-nuclear HII region of SDSS J143245.98+404300.3

2019 ◽  
Vol 630 ◽  
pp. A124
Author(s):  
Bruno Rodríguez Del Pino ◽  
Santiago Arribas ◽  
Javier Piqueras López ◽  
Alejandro Crespo Gómez ◽  
José M. Vílchez
Keyword(s):  
High Velocity ◽  
Stellar Winds ◽  
Hii Region ◽  
Star Forming ◽  
Spectral Signatures ◽  
Gas Kinematics ◽  
Spatially Resolved ◽  
Broad Emission ◽  
The Impact ◽  
Gas Component

We present and discuss the properties of an ionized gas component with extreme kinematics in a recently reported off-nuclear HII region located at ∼0.8−1.0 kpc from the nucleus of SDSS J143245.98+404300.3. The high-velocity-gas component is identified by the detection of very broad emission wings in the Hα line, with full width at half maximum (FWHM)  ≥ 850−1000 km s−1. Such gas kinematics are outstandingly high compared to other HII regions in local galaxies and are similar to those reported in some star-forming clumps of galaxies at z ∼ 2. The spatially resolved analysis indicates that the high-velocity gas extends at least ∼90 pc and it could be compatible with an ionized outflow entraining gas at a rate between approximately seven and nine times faster than the rate at which gas is being converted into stars. We do not detect broad emission wings in other emission lines such as Hβ, perhaps due to moderate dust extinction, nor in [N II]λλ6548, 6584 or [S II]λλ6717, 6731, which could be due to the presence of turbulent mixing layers originated by the impact of fast-flowing winds. The lack of spectral signatures associated to the presence of Wolf–Rayet stars points towards stellar winds from a large number of massive stars and/or supernovae as the likely mechanisms driving the high-velocity gas.

scholarly journals High Velocity Gas in the Orion Nebula

1980 ◽  
Vol 87 ◽  
pp. 33-38
Author(s):  
Nicholas Z. Scoville
Keyword(s):  
High Velocity ◽  
Center Of Mass ◽  
High Spectral Resolution ◽  
Collisional Excitation ◽  
Orion Nebula ◽  
Hii Region ◽  
The Core ◽  
Neutral Gas ◽  
Infrared Wavelengths ◽  
Co Emission

Observations at both millimeter and infrared wavelengths reveal energetic activity within the core of the Orion molecular cloud in the vicinity of the KL-BN cluster. New observations of the high velocity CO emission at 2.6-mm with improved angular resolution (HPBW = 44″) show that the source diameter averages 4 × 1017 cm and the center of mass is displaced 10-12″ north of the Kleinmann-Low nebula to a position close to the Becklin-Neugebauer object. The total mass of high velocity gas in the core region is ∼10 M⊙ (assuming 10% of the carbon is in CO); the present kinetic energy is 4 × 1047 ergs. Further evidence that BN may be the ultimate source of this energy is provided by high resolution infrared spectra which show both ionized and high temperature (Tk ≳ 3000 K) neutral gas in this source. CO bandhead emission (v = 2 → 0, 3 → 1, and 4 → 2) seen in BN is thought to arise from collisional excitation at high temperatures in a very dense (nH > 1010 cm−3) region only 1 AU in size. And high spectral resolution profiles of the Br α and γ recombination lines show that the HII region previously detected in BN apparently has motions over 100 km s−1.

scholarly journals ALMA imaging of the nascent planetary nebula IRAS 15103–5754

2018 ◽  
Vol 480 (4) ◽  
pp. 4991-5009 ◽  
Author(s):  
José F Gómez ◽  
Gilles Niccolini ◽  
Olga Suárez ◽  
Luis F Miranda ◽  
J Ricardo Rizzo ◽  
...  
Keyword(s):  
Mass Loss ◽  
High Velocity ◽  
Planetary Nebula ◽  
Symmetry Axis ◽  
Stellar System ◽  
Line Emission ◽  
Ionized Gas ◽  
Molecular Line ◽  
Common Envelope ◽  
Loss Event

ABSTRACT We present continuum and molecular-line (CO, C18O, HCO+) observations carried out with the Atacama Large Millimeter/submillimeter Array toward the ‘water fountain’ star IRAS 15103–5754, an object that could be the youngest planetary nebula (PN) known. We detect two continuum sources, separated by 0.39 ± 0.03 arcsec. The emission from the brighter source seems to arise mainly from ionized gas, thus confirming the PN nature of the object. The molecular-line emission is dominated by a circumstellar torus with a diameter of ≃0.6 arcsec (2000 au) and expanding at ≃23 km s−1. We see at least two gas outflows. The highest-velocity outflow (deprojected velocities up to 250 km s−1), traced by the CO lines, shows a biconical morphology, whose axis is misaligned ≃14° with respect to the symmetry axis of the torus, and with a different central velocity (by ≃8 km s−1). An additional high-density outflow (traced by HCO+) is oriented nearly perpendicular to the torus. We speculate that IRAS 15103–5754 was a triple stellar system that went through a common envelope phase, and one of the components was ejected in this process. A subsequent low-collimation wind from the remaining binary stripped out gas from the torus, creating the conical outflow. The high velocity of the outflow suggests that the momentum transfer from the wind is extremely efficient, or that we are witnessing a very energetic mass-loss event.

scholarly journals Large scale interaction of the outflow and quiescent gas in Orion

1991 ◽  
Vol 147 ◽  
pp. 456-457
Author(s):  
J. Martin-Pintado ◽  
A. Rodriguez-Franco ◽  
R. Bachiller
Keyword(s):  
Spatial Distribution ◽  
High Velocity ◽  
Large Scale ◽  
High Sensitivity ◽  
Molecular Flow ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Transition Analysis ◽  
Molecular Outflow ◽  
Hh Objects

The IRAM 30-m radiotelescope have been used to obtain, with high angular resolution, the spatial distribution and the physical conditions of the quiescent gas in Orion A, and to search for high velocity molecular gas far away from the well known molecular outflow around IRc2. To study the quiescent gas we mapped a region of 200″×300″ around IRc2 in the J=12-11 and J=16-15 lines of HC3N with angular resolutions of 22″ and 17″ respectively. The left panel of Fig. 1 shows the spatial distribution of the high density quiescent gas around IRc2 for different radial velocities. Beside the already known molecular ridge north of IRc2 (see e. g. Bartla et al. 1983), we find four very thin (nearly unresolved) and long filaments, like “fingers”, stretching from IRc2 to the north and west. The deconvolved size of the longest fingers is ≈180″×15″. From a multi-transition analysis of the HC3N emission we derive H2 densities of 1−8 105 cm−3, kinetic temperatures larger than 40 K and masses of ≈10 Mo. Our high sensitivity observations of the J=2-1 line of CO at selected positions (see right panel ib Fig. 1) show widespread molecular gas with high velocities wings over the region where the molecular fingers and the HH objects are observed (see Fig.1). The high velocity emission occurs over a range of ±40 kms−1. This high velocity gas is more extended (up to 150″ from IRc2) than the very compact (40″) and well studied molecular outflow around IRc2 (see e.g. Wilson et al. 1986). The terminal velocities of the CO wings decrease from 100 km s−1 (corresponding to the very fast molecular flow) to the typical terminal velocities of the extended high velocity gas when the distance to IRc2 changes from 40″ to 60″. The origin of the large scale high velocity gas is unknown, but it is very likely the link between the very compact (40″) and fast (±100 km s−1) molecular outflow around IRc2 and the ionized high velocity gas and the HH objects (Martín-Pintado et al. 1990). The mass, momentum and energy of the extended high velocity gas are crudely estimated to be ≈1 Mo, ≈20 Mo km s−1 and ≈2 1045 erg respectively (i.e. a factor of ≈10 smaller than those of the fast molecular outflow). The location, at the edges of the molecular fingers, and the proper motions of the HH objects (see Fig. 1) suggest the stellar wind is interacting with the molecular fingers. If this interpretation is correct, the influence of the molecular outflow in Orion on the surrounding molecular clouds must be revised.

scholarly journals Stellar formation in HI interstellar bubbles around massive stars

2006 ◽  
Vol 2 (S237) ◽  
pp. 444-444
Author(s):  
M. C. Martín ◽  
G. A. Romero ◽  
C. E. Cappa
Keyword(s):  
Mechanical Energy ◽  
Line Emission ◽  
Radio Continuum ◽  
Stellar Winds ◽  
Neutral Gas ◽  
Stellar Formation ◽  
Energy And Momentum ◽  
Expanding Shells ◽  
Optical Ring ◽  
Ring Nebulae

Stellar winds from O and WR stars transfer large amounts of mechanical energy and momentum into the interstellar medium. They sweep up and compress the interstellar material, creating interstellar bubbles. These structures are detected as optical ring nebulae, as thermal radio continuum sources, as infrared shells, as neutral gas voids and expanding shells in the HI line emission distribution, and as molecular shells.

scholarly journals Large scale interaction of the outflow and quiescent gas in Orion

1991 ◽  
Vol 147 ◽  
pp. 456-457
Author(s):  
J. Martin-Pintado ◽  
A. Rodriguez-Franco ◽  
R. Bachiller
Keyword(s):  
Spatial Distribution ◽  
High Velocity ◽  
Large Scale ◽  
High Sensitivity ◽  
Molecular Flow ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Transition Analysis ◽  
Molecular Outflow ◽  
Hh Objects

The IRAM 30-m radiotelescope have been used to obtain, with high angular resolution, the spatial distribution and the physical conditions of the quiescent gas in Orion A, and to search for high velocity molecular gas far away from the well known molecular outflow around IRc2. To study the quiescent gas we mapped a region of 200″×300″ around IRc2 in the J=12-11 and J=16-15 lines of HC3N with angular resolutions of 22″ and 17″ respectively. The left panel of Fig. 1 shows the spatial distribution of the high density quiescent gas around IRc2 for different radial velocities. Beside the already known molecular ridge north of IRc2 (see e. g. Bartla et al. 1983), we find four very thin (nearly unresolved) and long filaments, like “fingers”, stretching from IRc2 to the north and west. The deconvolved size of the longest fingers is ≈180″×15″. From a multi-transition analysis of the HC3N emission we derive H2 densities of 1−8 105 cm−3, kinetic temperatures larger than 40 K and masses of ≈10 Mo. Our high sensitivity observations of the J=2-1 line of CO at selected positions (see right panel ib Fig. 1) show widespread molecular gas with high velocities wings over the region where the molecular fingers and the HH objects are observed (see Fig.1). The high velocity emission occurs over a range of ±40 kms−1. This high velocity gas is more extended (up to 150″ from IRc2) than the very compact (40″) and well studied molecular outflow around IRc2 (see e.g. Wilson et al. 1986). The terminal velocities of the CO wings decrease from 100 km s−1 (corresponding to the very fast molecular flow) to the typical terminal velocities of the extended high velocity gas when the distance to IRc2 changes from 40″ to 60″. The origin of the large scale high velocity gas is unknown, but it is very likely the link between the very compact (40″) and fast (±100 km s−1) molecular outflow around IRc2 and the ionized high velocity gas and the HH objects (Martín-Pintado et al. 1990). The mass, momentum and energy of the extended high velocity gas are crudely estimated to be ≈1 Mo, ≈20 Mo km s−1 and ≈2 1045 erg respectively (i.e. a factor of ≈10 smaller than those of the fast molecular outflow). The location, at the edges of the molecular fingers, and the proper motions of the HH objects (see Fig. 1) suggest the stellar wind is interacting with the molecular fingers. If this interpretation is correct, the influence of the molecular outflow in Orion on the surrounding molecular clouds must be revised.

scholarly journals SPECTROSCOPY OF THE ORION MOLECULAR CLOUD CORE

1981 ◽  
Vol 96 ◽  
pp. 187-205 ◽  
Author(s):  
N. Z. Scoville
Keyword(s):  
Molecular Cloud ◽  
Thermal Structure ◽  
Line Emission ◽  
Outer Radius ◽  
Emission Region ◽  
Vibrationally Excited ◽  
Hii Region ◽  
Brightness Temperatures ◽  
Neutral Gas ◽  
Expansion Time

Recent infrared and radio spectroscopic data pertaining to the Orion BN-KL infrared cluster are reviewed. A new, high resolution CO map shows that the thermal structure over the central 10′(1.5 pc) in the Orion molecular cloud is dominated by energy sources in the infrared cluster and M42. Peak CO brightness temperatures of 90 K occur on KL and near the bar at the southern edge of M42.Within the central 45″ of the infrared cluster, both radio and IR data reveal a highly energetic environment. Millimeter lines of several molecules (e.g. CO, HCN, and SiO) show emission over a full velocity range of 100 km s−1. These supersonic flows can be modeled as a differentially expanding envelope containing a total of ~5 M⊙ of gas within an outer radius of r ≃ 1.3 × 1017 cm. Over the same area emission is seen from vibrationally excited molecular hydrogen at an excitation temperature of 2000 K. The high velocity mm-line emission and the NIR H2 lines are clearly related since they exhibit similar spatial extents and line widths. Comparison of the total cooling rate for all the H2 lines with the estimated kinetic energy and expansion time for the mm-emission region indicates that the H2 emission probably arises from shock fronts where the expanding envelope impinges on the outer cloud.Near IR spectroscopy also probes ionized and neutral gas closely associated with BN. Br α and Br γ emission is detected from an ultracompact HII region of mass MHII ≲ 10−4 M⊙. Full widths for the HII lines are ~400 km s−1. CO bandhead emission detected in BN at λ ≃ 2.3 μm is probably collisionally pumped in a high excitation zone (nH+H2 > 1010 cm−3 and TK ≃ 3000 K) at only a few AU from the star. The velocity of both the HII and CO emission is VLSR ≃ + 20 km s−1; thus BN appears to be redshifted by 11 km s−1 with respect to OMC-1.

ATOMIZATION CHARACTERISTICS OF LIQUID JETS INJECTED INTO A HIGH-VELOCITY FLOW FIELD

1994 ◽  
Vol 4 (4) ◽  
pp. 451-471 ◽  
Author(s):  
Nobuyuki Yatsuyanagi ◽  
Hiroshi Sakamoto ◽  
Kazuo Sato
Keyword(s):  
Flow Field ◽  
High Velocity ◽  
Liquid Jets ◽  
High Velocity Flow ◽  
Velocity Flow ◽  
Atomization Characteristics
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