scholarly journals High-Resolution Molecular Line Observations of the Core and Outflow in Orion B

1989 ◽  
Vol 120 ◽  
pp. 339-339
Author(s):  
J.S. Richer ◽  
R.E. Hills ◽  
R. Padman
Keyword(s):  
High Resolution ◽  
Central Axis ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Excitation Temperature ◽  
Molecular Line ◽  
Core Mass ◽  
The Core ◽  
Molecular Outflow ◽  
Cloud Core

High-resolution CO J → 1 → 2 observations of the Orion B molecular outflow show that the outflow is unipolar, and that there is evidence of acceleration of molecular gas at up to 0.5pc from the driving star. The highest-velocity material, as well as being furthest from the source, seems to lie close to the central axis of the flow, and is presumably being accelerated by entrainment in the flow or jet emanating from the star. We have also mapped the HCO+J = 3 → 2 emission at 19-arcsec resolution. We derive an excitation temperature of around 25 K in the cloud core, and a core mass of about 75 M⊙, this estimate is in accord with a model in which the core has a kinetic temperature of 30-50 K, with no molecular depletion on to grains. This is in contrast to the recent suggestion that the core contains cold isothermal protostars.

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 A multi-molecular line study of the star-forming globule CB88-230

2019 ◽  
Vol 628 ◽  
pp. A98
Author(s):  
J. Brand ◽  
J. G. A. Wouterloot ◽  
C. Codella ◽  
F. Massi ◽  
A. Giannetti
Keyword(s):  
Large Scale ◽  
Spectral Energy Distribution ◽  
Turbulent Energy ◽  
Volume Density ◽  
Spectral Energy ◽  
Mass Star ◽  
Molecular Line ◽  
Star Forming ◽  
The Core ◽  
Molecular Outflow

Context. This paper relates to low-mass star formation in globules, and the interaction of newly-formed stars with their environment. We follow up on the results of our earlier observations of this globule. Aims. Our aim is to study the gas- and dust environment of the young stellar object (YSO) in globule CB88 230, the large-scale molecular outflow triggered by the jet driven by the YSO, and their interaction. Methods. We carried out submillimetre continuum and multi-line molecular observations with several single-dish facilities, mapping the core of the globule and the large-scale outflow associated with the YSO. Results. Dust continuum and molecular line maps (of 12CO, C18O, CS, CH3OH) show a flattened (axes ratio 1.5−1.7), asymmetric core with a full width at half maximum (FWHM)-diameter of 0.16−0.21 pc. Line profiles of 12CO, 13CO(2–1, 3–2), and CS(2–1) show self-absorption near the YSO; the absorption dip is at a slightly (~0.3 km s−1) redder velocity than that of the quiescent gas, possibly indicating infall of cooler envelope gas. The mass of the core, determined from C18O(1–0) observations, is about 8 M⊙, while the virial mass is in the range 5−8M⊙, depending on the assumed density distribution. We detect a slight velocity gradient (~0.98 km s−1 pc−1), though rotational energy is negligible with respect to gravitational and turbulent energy of the core. A fit to the spectral energy distribution of the core gives a dust temperature Td ≈ 18 K and a gas mass of ca. 2 M⊙ (assuming a gas-to-dust ratio of 100). More careful modelling of the sub-mm emission (not dominated by the relatively hot central regions) yields M ≈ 8M⊙. From the molecular line observations we derive gas temperatures of 10−20 K. A Bayesian analysis of the emission of selected molecules observed towards the YSO, yields Tkin ≈ 21.4 K (68% credibility interval 14.5−35.5 K) and volume density n(H2) ≈ 4.6 × 105 cm−3 (8.3 × 104−9.1 × 105 cm−3). We have mapped the well-collimated large-scale outflow in 12CO(3–2). The outflow has a dynamical age of a few 104 yr, and contains little mass (a few 10−2 M⊙). A misalignment between the axis of this large-scale outflow and that of the hot jet close to the YSO indicates that the outflow direction may be changing with time.

scholarly journals An 8″ resolution CO (J=3−2) map of IC342

1991 ◽  
Vol 147 ◽  
pp. 460-461
Author(s):  
R. Mauersberger ◽  
A. Schulz ◽  
J.W.M. Baars ◽  
H. Steppe
Keyword(s):  
Molecular Species ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Molecular Line ◽  
Strong Emission ◽  
Continuum Radiation ◽  
Spiral Arms ◽  
Multi Level ◽  
Gas Component

IC342 (Distance 4 Mpc) is one of the most suitable sources for extragalactic molecular line studies. Toward its nucleus, a great number of molecular species have been found (see Henkel and Mauersberger, 1990); it is also one of the few galaxies investigated in molecular multi-level studies (Mauersberger and Henkel, 1989). In particular, CO shows strong emission: A 7″ resolution interferometric map of the central parts of this galaxy in the 12CO(1—0) transition by Lo et al. (1984) reveals that the circumnuclear molecular gas is distributed in a bar (size 15″ × 70″) (330 × 1500 pc) extending from the nucleus towards the spiral arms. An interferometric map of the 1—0 line of CO by Ishizuki et al. (1990) shows that the inner part of the bar forms a molecular ring of diameter 110 pc. This inner ring also emits 2 and 6 cm continuum radiation (Turner and Ho, 1983). The kinetic temperature of the denser molecular gas is > 50 K (Martin and Ho, 1986). The H2 density of the gas component seen in CO (Eckart et al., 1990) and CS (Mauersberger and Henkel, 1989) is ∼ 104 cm−3.

scholarly journals Cold Molecular Material in the Galaxy

1983 ◽  
Vol 100 ◽  
pp. 45-46
Author(s):  
Neal J. Evans ◽  
S. R. Federman ◽  
F. Combes ◽  
E. Falgarone
Keyword(s):  
Molecular Clouds ◽  
Total Mass ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Low Density ◽  
Excitation Temperature ◽  
Molecular Material ◽  
The Galaxy

The kinetic temperatures in molecular clouds are usually considered to range upward from about 10 K (e.g., Dickman 1975). These temperatures are generally measured by observing the CO J = 1 → 0 transition and assuming that this line is optically thick and thermalized. This assumption also underlies estimates of the total mass and distribution of molecular material in our galaxy based on CO surveys. Because a significant amount of molecular material could in principle be missed by galactic CO surveys, a search was undertaken for “ultra-cold” molecular gas, by which is meant an excitation temperature, Tex < 5 K. No evidence was found for a large amount of such material (Evans, Rubin, and Zuckerman 1980), but many clouds with Tex between 5 and 10 K were found. To determine if this low Tex is due to low kinetic temperature, low density, or low CO abundance, we have undertaken observations of a large number of clouds in the J = 2 → 1 CO line and the J = 1 → 0 13CO and CO lines. These observations will be analyzed to determine the properties of these clouds.

scholarly journals High Resolution Observations of Molecular Gas in the Outflow of M 82

2004 ◽  
Vol 217 ◽  
pp. 314-315
Author(s):  
Fabian Walter ◽  
Axel Weiss ◽  
Nick Scoville
Keyword(s):  
High Resolution ◽  
Mechanical Energy ◽  
Opening Angle ◽  
Molecular Gas ◽  
Molecular Outflow ◽  
Outflow Velocity ◽  
Line Splitting ◽  
Total Mechanical Energy ◽  
First Time ◽  
Absorption Features

We present a high-resolution (3.6“, 70 pc) CO(1-0) mosaic of the molecular gas in M 82 covering an area of 2.5'x3.5’ (2.8 kpc x 3.9 kpc) obtained with the OVRO millimeter interferometer. The observations reveal the presence of huge amounts of molecular gas (> 70% of the total molecular mass, Mtot ≈ 1.3 × 109M⊙) outside the central 1 kpc disk. Molecular streamers are detected in and below M 82's disk out to distances from the center of ~1.7 kpc. Some of these streamers are well correlated with optical absorption features; they form the basis of some of the prominent tidal HI features around M 82. This provides evidence that the molecular gas within M 82's optical disk is disrupted by the interaction with M 81. Molecular gas is found in M 82's outflow/halo, reaching distances up to 1.2 kpc below the plane; CO line-splitting has been detected for the first time in the outflow. The maximum outflow velocity is ~ 230 km s−1; we derive an opening angle of ~ 55° for the molecular outflow cone. The total amount of gas in the outflow is > 3 × 108 M⊙ and its kinetic energy is of order 1055 erg, about one percent of the estimated total mechanical energy input of M 82's starburst. Our study implies that extreme starburst environments can move significant amounts of molecular gas in to a galaxy's halo (and even to the intergalactic medium).

scholarly journals Star Formation: Can There BE a Break in the IMF Near 0.1Mʘ?

1998 ◽  
Vol 11 (1) ◽  
pp. 425-426
Author(s):  
Takenori Nakano
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Small Mass ◽  
Initial Mass Function ◽  
Core Mass ◽  
The Core ◽  
Cloud Cores ◽  
Formation Efficiency ◽  
Cloud Core ◽  
The Imf

The initial mass function of stars (IMF) at small masses depends on several factors. First, it depends on the mass function of cloud cores in which stars form. Second, there must be a lower limit to the core mass for contraction; very small mass cores may not contract even if they exist. This must affect greatly the IMF near its lower end. Third, not all core matter may become stars; we must determine the stellar mass M*, or the star formation efficiency M*/Mcc, as a function of the mass of the cloud core, Mcc. In this paper we discuss the second and third points.

scholarly journals An 8″ resolution CO (J=3−2) map of IC342

1991 ◽  
Vol 147 ◽  
pp. 460-461
Author(s):  
R. Mauersberger ◽  
A. Schulz ◽  
J.W.M. Baars ◽  
H. Steppe
Keyword(s):  
Molecular Species ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Molecular Line ◽  
Strong Emission ◽  
Continuum Radiation ◽  
Spiral Arms ◽  
Multi Level ◽  
Gas Component

IC342 (Distance 4 Mpc) is one of the most suitable sources for extragalactic molecular line studies. Toward its nucleus, a great number of molecular species have been found (see Henkel and Mauersberger, 1990); it is also one of the few galaxies investigated in molecular multi-level studies (Mauersberger and Henkel, 1989). In particular, CO shows strong emission: A 7″ resolution interferometric map of the central parts of this galaxy in the 12CO(1—0) transition by Lo et al. (1984) reveals that the circumnuclear molecular gas is distributed in a bar (size 15″ × 70″) (330 × 1500 pc) extending from the nucleus towards the spiral arms. An interferometric map of the 1—0 line of CO by Ishizuki et al. (1990) shows that the inner part of the bar forms a molecular ring of diameter 110 pc. This inner ring also emits 2 and 6 cm continuum radiation (Turner and Ho, 1983). The kinetic temperature of the denser molecular gas is > 50 K (Martin and Ho, 1986). The H2 density of the gas component seen in CO (Eckart et al., 1990) and CS (Mauersberger and Henkel, 1989) is ∼ 104 cm−3.

scholarly journals High-resolution molecular line observations of the core and outflow in Orion B

1989 ◽  
Vol 241 (2) ◽  
pp. 231-246 ◽  
Author(s):  
John S. Richer ◽  
Richard E. Hills ◽  
Rachael Padman ◽  
Adrian P. G. Russell
Keyword(s):  
High Resolution ◽  
Molecular Line ◽  
The Core

scholarly journals Excitation and acceleration of molecular outflows in LIRGs: The extended ESO 320-G030 outflow on 200-pc scales

2020 ◽  
Vol 643 ◽  
pp. A89
Author(s):  
M. Pereira-Santaella ◽  
L. Colina ◽  
S. García-Burillo ◽  
E. González-Alfonso ◽  
A. Alonso-Herrero ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Velocity Structure ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Total Size ◽  
Luminous Infrared Galaxies ◽  
Molecular Outflow ◽  
The Galaxy ◽  
Galaxy Disk ◽  
Self Gravity

We used high-spatial resolution (70 pc; 0$ {{\overset{\prime\prime}{.}}} $3) CO multi-transition (J = 1–0, 2–1, 4–3, and 6–5) ALMA data to study the physical conditions and kinematics of the cold molecular outflow in the local luminous infrared galaxy (LIRG) ESO 320-G030 (d = 48 Mpc, LIR/L⊙ = 1011.3). ESO 320-G030 is a double-barred isolated spiral, but its compact and obscured nuclear starburst (SFR ∼ 15 M⊙ yr−1; AV ∼ 40 mag) resembles those of ultra-luminous infrared galaxies (LIR/L⊙ > 1012). In the outflow, the CO(1–0)/CO(2–1) ratio is enhanced with respect to the rest of the galaxy and the CO(4–3) transition is undetected. This indicates that the outflowing molecular gas is less excited than the molecular gas in the nuclear starburst (i.e., outflow launching site) and in the galaxy disk. Non-local thermodynamic equilibrium radiative transfer modeling reveals that the properties of the molecular clouds in the outflow differ from those of the nuclear and disk clouds: The kinetic temperature is lower (Tkin ∼ 9 K) in the outflow, and the outflowing clouds have lower column densities. Assuming a 10−4 CO abundance, the large internal velocity gradients, 60−45+250 km s−1 pc−1, imply that the outflowing molecular clouds are not bound by self-gravity. All this suggests that the life-cycle (formation, collapse, dissipation) of the galaxy disk molecular clouds might differ from that of the outflowing molecular clouds which might not be able to form stars. The low kinetic temperature of the molecular outflow remains constant at radial distances between 0.3 and 1.7 kpc. This indicates that the heating by the hotter ionized outflow phase is not efficient and may favor the survival of the molecular gas phase in the outflow. The spatially resolved velocity structure of the outflow shows a 0.8 km s−1 pc−1 velocity gradient between 190 pc and 560 pc and then a constant maximum outflow velocity of about 700–800 km s−1 up to 1.7 kpc. This could be compatible with a pure gravitational evolution of the outflow, which would require coupled variations of the mass outflow rate and the outflow launching velocity distribution. Alternatively, a combination of ram pressure acceleration and cloud evaporation could explain the observed kinematics and the total size of the cold molecular phase of the outflow.

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