scholarly journals High resolution molecular hydrogen imaging of the Ring Nebula

2003 ◽  
Vol 209 ◽  
pp. 271-271
Author(s):  
A. K. Speck ◽  
M. Meixner ◽  
P. Knezek ◽  
G. H. Jacoby
Keyword(s):  
High Resolution ◽  
Ionizing Radiation ◽  
Molecular Hydrogen ◽  
Planetary Nebulae ◽  
Molecular Gas ◽  
Gas Bubble ◽  
Gas Emission ◽  
Ionized Gas ◽  
Neutral Gas ◽  
Ring Nebula

The relative morphologies and structures of molecular and ionized gas emission from planetary nebulae (PNe) allow a better understanding of the nature and evolution of these objects. The classical paradigm for the structure of PNe is that of an ionized gas bubble bounded by neutral gas and molecules. However, it has been shown that molecular gas exists within ionized regions, leading to a re-evaluation of the classic structure. In the Helix Nebula (NGC 7293) dense condensations known as cometary knots are known to exist in the main ionized nebula. The molecules in these knots are shielded from the ionizing radiation and thus survive within the ionized zone. Another PN in which H2 emission is seen to originate from within the ionized nebula in NGC 6720 (the Ring Nebula).

scholarly journals High Resolution Observations of CO in Planetary Nebulae

1994 ◽  
Vol 140 ◽  
pp. 143-147
Author(s):  
K.M. Shibata ◽  
S. Deguchi ◽  
T. Kasuga ◽  
S. Tamura ◽  
N. Hirano ◽  
...  
Keyword(s):  
High Resolution ◽  
Planetary Nebulae ◽  
Aperture Synthesis ◽  
Molecular Gas

AbstractIn order to examine the structure and kinematics of the molecular gas around planetary nebulae, we have made aperture synthesis observations of I2CO(J=1-0) emission in three planetary nebulae, IRAS 21282+5050, CRL 618 and M 1-7, using Nobeyama Millimeter Array.

scholarly journals On the Propagation and Structure of Ionization Fronts

1958 ◽  
Vol 8 ◽  
pp. 1062-1068
Author(s):  
F. A. Goldsworthy
Keyword(s):  
Shock Wave ◽  
Ionizing Radiation ◽  
Atomic Hydrogen ◽  
Hydrogen Gas ◽  
Ionization Front ◽  
Ionized Gas ◽  
Hii Region ◽  
Ionization Fronts ◽  
Neutral Gas ◽  
Gravitational Equilibrium

The problem discussed here is that of determining the motion of a cloud of neutral atomic hydrogen gas, when it is subjected to ionizing radiation from a star embedded in it. Initially the gas is in gravitational equilibrium at a constant temperature of about 100°K. It is supposed that at time t=0 the star suddenly begins to radiate with a certain intensity, which remains constant thereafter. Part of the surrounding gas will be ionized and an ionization front (separating the ionized gas from the neutral gas) will move outwards into the neutral gas. A shock wave may also propagate ahead of the ionization front into the neutral gas. There will therefore be two regions to consider—a region of ionized gas (HII region) and a region of neutral gas (HI region) in which there may be a shock.

scholarly journals Study of the molecular gas in the central parsec of the Galaxy through regularized 3D spectroscopy

2013 ◽  
Vol 9 (S303) ◽  
pp. 83-85
Author(s):  
A. Ciurlo ◽  
T. Paumard ◽  
D. Rouan ◽  
Y. Clénet
Keyword(s):  
Molecular Gas ◽  
Imaging Data ◽  
Ionized Gas ◽  
Central Cavity ◽  
Neutral Gas ◽  
The Galaxy ◽  
Circumnuclear Disk ◽  
Cool Gas ◽  
Central Parsec ◽  
Spectro Imaging

AbstractThe cool gas in the central parsec of the Galaxy is organized in the surrounding circumnuclear disk, made of neutral gas, and the internal minispiral, composed of dust and ionized gas. In order to study the transition between them we have investigated the presence of H2 neutral gas in this area, through NIR spectro-imaging data observed with SPIFFI. To preserve the spatial resolution we implemented a new method consisting of a regularized 3D fit. We concentrated on the supposedly fully ionized central cavity and the very inner edge of the CND. H2 is detected everywhere: at the boundary of the CND and in the central cavity, where it seems to split in two components, one in the background of the minispiral and one inside the Northern arm.

scholarly journals Dense Molecular Gas at High Redshift: First Detection of Emission from HCO+

2006 ◽  
Vol 2 (S235) ◽  
pp. 424-424
Author(s):  
D.A. Riechers ◽  
F. Walter ◽  
C.L. Carilli ◽  
A. Weiss ◽  
F. Bertoldi ◽  
...  
Keyword(s):  
Molecular Hydrogen ◽  
Molecular Clouds ◽  
High Redshift ◽  
Far Infrared ◽  
Hydrogen Gas ◽  
Molecular Gas ◽  
Gas Emission ◽  
Very Large Array ◽  
Star Forming ◽  
Good Tracer

AbstractUsing the Very Large Array (VLA), we have detected the HCO+(1–0) emission line towards the Cloverleaf quasar (z = 2.56; Riechers et al. 2006). This is the first detection of ionized molecular gas emission at high redshift (z>2). HCO+ emission is a star formation indicator similar to HCN, tracing dense molecular hydrogen gas within star-forming molecular clouds. We find a HCO+/CO luminosity ratio of 0.08 and a HCO+/HCN luminosity ratio of 0.8 for the Cloverleaf. These ratios fall within the scatter of the same relationships found for low–z star–forming galaxies. However, a HCO+/HCN luminosity ratio close to unity would not be expected for the Cloverleaf if the recently suggested relation between this ratio and the far–infrared luminosity (Graciá–Carpio et al. 2006) were to hold. We conclude that a ratio between HCO+ and HCN luminosity close to 1 is likely due to the fact that the emission from both lines is optically thick and thermalized and emerges from dense regions of similar volumes. We conclude that HCO+ is potentially a good tracer for dense molecular gas at high redshift.

scholarly journals Multiphase outflows in post-starburst E+A galaxies - II. A direct connection between the neutral and ionized outflow phases

2020 ◽  
Vol 494 (4) ◽  
pp. 5396-5420 ◽  
Author(s):  
Dalya Baron ◽  
Hagai Netzer ◽  
Ric I Davies ◽  
J Xavier Prochaska
Keyword(s):  
Molecular Gas ◽  
Mass Ratio ◽  
Ionized Gas ◽  
Gas Phases ◽  
Spatially Resolved ◽  
Neutral Gas ◽  
Major Merger ◽  
A Minor ◽  
First Time ◽  
Photoionization Model

ABSTRACT Post-starburst E+A galaxies are systems that hosted a powerful starburst that was quenched abruptly. Simulations suggest that these systems provide the missing link between major merger ULIRGs and red and dead ellipticals, where AGN feedback is responsible for the expulsion or destruction of the molecular gas. However, many details remain unresolved and little is known about AGN-driven winds in this short-lived phase. We present spatially resolved IFU spectroscopy with MUSE/VLT of SDSS J124754.95-033738.6, a post-starburst E+A galaxy with a recent starburst that started 70 Myr ago and ended 30 Myr ago, with a peak SFR of $\sim 150\, \mathrm{M_{\odot }\,yr^{ -1}}$. We detect disturbed gas throughout the entire field of view, suggesting triggering by a minor merger. We detect fast-moving multiphased gas clouds, embedded in a double-cone face-on outflow, which are traced by ionized emission lines and neutral NaID emission and absorption lines. We find remarkable similarities between the kinematics, spatial extents, and line luminosities of the ionized and neutral gas phases, and propose a model in which they are part of the same outflowing clouds, which are exposed to both stellar and AGN radiation. Our photoionization model provides consistent ionized line ratios, NaID absorption optical depths and EWs, and dust reddening. Using the model, we estimate, for the first time, the neutral-to-ionized gas mass ratio (about 20), the sodium neutral fraction, and the size of the outflowing clouds. This is one of the best ever observed direct connections between the neutral and ionized outflow phases in AGN.

scholarly journals Magnetic Field of a Contracting Protostar

1958 ◽  
Vol 8 ◽  
pp. 1020-1022
Author(s):  
L. Mestel
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Energy Density ◽  
Ionizing Radiation ◽  
Lower Limit ◽  
Thermal Energy ◽  
Magnetic Energy ◽  
Magnetic Pressure ◽  
Ionized Gas ◽  
Neutral Gas

In a recent paper, Mestel and Spitzer discussed the problem of star formation from cool matter in the presence of a magnetic field of energy density comparable with the thermal energy density. If the field were frozen into the gas, the magnetic pressure would put a lower limit of order 103M⊙ to the mass that could be gravitationally bound, and this limit is unaltered by contraction of the cloud. However, in a lightly ionized gas, the field moves not with the gas as a whole, but with the plasma, and the motion of the plasma through the cloud is determined by a balance between mgnetic force and friction between neutral gas and plasma. A cloud containing sufficient dust can extinguish the galactic ionizing radiation; the plasma density decays quickly enough for the plasma and neutral gas to become uncoupled during the time of gravitational contraction. In this way high densities are built up without correspondingly high magnetic energy, and the cloud can break up into stars.

scholarly journals Dynamical Evolution of a Model Planetary Nebula

1968 ◽  
Vol 34 ◽  
pp. 273-274
Author(s):  
W. G. Mathews
Keyword(s):  
Ionizing Radiation ◽  
Planetary Nebula ◽  
Dynamical Evolution ◽  
Planetary Nebulae ◽  
Dynamical Equations ◽  
Conservation Of Mass ◽  
Neutral Gas ◽  
Image Position

The gas-dynamical equations for conservation of mass, momentum and energy, the ionization equation, and the equation of transfer for the ionizing radiation have been solved in a manner which approximates conditions in planetary nebulae. The ionized and neutral gas are assumed to heat and cool according to a linearized rate proportional to

scholarly journals HCO+ emission possibly related with a shielding mechanism that protects water molecules in the young PN K 3-35

2008 ◽  
Vol 4 (S251) ◽  
pp. 173-174 ◽  
Author(s):  
Y. Gómez ◽  
D. Tafoya ◽  
G. Anglada ◽  
L. Loinard ◽  
J. M. Torrelles ◽  
...  
Keyword(s):  
Water Vapor ◽  
Ionizing Radiation ◽  
Large Distance ◽  
Organic Molecules ◽  
Planetary Nebulae ◽  
Molecular Gas ◽  
Water Molecules ◽  
Unknown Mechanism ◽  
Maser Emission ◽  
Water Maser

AbstractWater maser emission has been detected only toward three planetary nebulae (PNe). In particular, in K3-35, the first PN where water vapor maser emission was detected, the components are located in a torus-like structure with a radius of 85 AU and also at the surprisingly large distance of 5000 AU from the star, in the tips of the bipolar lobes. The existence of these water molecules in PNe is puzzling, probably related to some unknown mechanism shielding them against the ionizing radiation. We report the detection of HCO+ (J = 1 − 0) emission toward K 3-35, that not only suggests that dense molecular gas (~105 cm−3) is present in this PN, but also that this kind of PN can enrich their surroundings with organic molecules.

scholarly journals The relation between the radio jet and the near-IR line emission in Seyfert galaxies

2010 ◽  
Vol 6 (S275) ◽  
pp. 172-173
Author(s):  
Rogemar A. Riffel ◽  
Thaisa Storchi-Bergmann
Keyword(s):  
Line Emission ◽  
Seyfert Galaxies ◽  
Molecular Gas ◽  
Gas Emission ◽  
Ionized Gas ◽  
Integral Field Spectroscopy ◽  
Near Ir ◽  
Field Spectroscopy ◽  
Molecular Flux ◽  
Integral Field

AbstractWe used near-IR integral field spectroscopy, obtained with Gemini NIFS and GNIRS integral field units (IFUs), to map the ionized and molecular flux distributions and kinematics in the central few hundreds of parsecs of Seyfert galaxies. We conclude that the molecular gas emission can be considered a tracer of the feeding of the AGN, while the emission of the ionized gas a tracer of its feedback.

scholarly journals Chemical Evolution of Turbulent Multiphase Molecular Clouds

2017 ◽  
Vol 13 (S332) ◽  
pp. 242-248
Author(s):  
Valeska Valdivia ◽  
Patrick Hennebelle ◽  
Benjamin Godard ◽  
Maryvonne Gerin ◽  
Pierre Lesaffre ◽  
...  
Keyword(s):  
High Resolution ◽  
Chemical Evolution ◽  
Molecular Hydrogen ◽  
Molecular Clouds ◽  
Formation Time ◽  
Molecular Gas ◽  
Low Density

AbstractMolecular clouds are essentially made up of atomic and molecular hydrogen, which in spite of being the simplest molecule in the ISM plays a key role in the chemical evolution of molecular clouds. Since its formation time is very long, the H2 molecules can be transported by the turbulent motions within the cloud toward low density and warm regions, where its enhanced abundance can boost the abundances of molecules with high endothermicities.We present high resolution simulations where we include the evolution of the molecular gas under the effect of the dynamics, and we analyze its impact on the abundance of CH+.

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