scholarly journals Probing Gas Kinematics and PDR Structure around O-type Stars in the Sh 2-305 H ii Region

2021 ◽  
Vol 922 (2) ◽  
pp. 207
Author(s):  
N. K. Bhadari ◽  
L. K. Dewangan ◽  
P. M. Zemlyanukha ◽  
D. K. Ojha ◽  
I. I. Zinchenko ◽  
...  
Keyword(s):  
Gas Dynamics ◽  
Total Mass ◽  
Gravitational Instability ◽  
Outer Shell ◽  
Compact Ring ◽  
Gas Kinematics ◽  
H Ii Region ◽  
Photodissociation Regions ◽  
Shell Geometry ◽  
Velocity Channel

Abstract We report an observational study of the Galactic H ii region Sh 2-305/S305 using the [C ii] 158 μm line data, which are used to examine the gas dynamics and structure of photodissociation regions. The integrated [C ii] emission map at [39.4, 49.5] km s−1 spatially traces two shell-like structures (i.e., inner and outer neutral shells) having a total mass of ∼565 M ⊙. The inner neutral shell encompasses an O9.5V star at its center and has a compact ring-like appearance. However, the outer shell is seen with more extended and diffuse [C ii] emission, hosting an O8.5V star at its center, and surrounds the inner neutral shell. The velocity channel maps and position–velocity diagrams confirm the presence of a compact [C ii] shell embedded in the diffuse outer shell, and both the shells seem to expand with v exp ∼ 1.3 km s−1. The outer shell appears to be older than the inner shell, hinting that these shells are formed sequentially. The [C ii] profiles are examined toward S305, which are either double peaked or blue skewed and have the brighter redshifted component. The redshifted and blueshifted components spatially trace the inner and outer neutral shell geometry, respectively. The ionized, neutral, and molecular zones in S305 are seen adjacent to one another around the O-type stars. The regularly spaced dense molecular and dust clumps (mass ∼10–103 M ⊙) are investigated around the neutral shells, which might have originated as a result of gravitational instability in the shell of collected materials.

Gas dynamics and star formation in “isolated” and interacting galaxies using FP observations

2019 ◽  
Vol 14 (S353) ◽  
pp. 264-265
Author(s):  
Isaura Fuentes-Carrera ◽  
Nelli Cárdenas-Martínez ◽  
Martín Nava-Callejas ◽  
Margarita Rosado
Keyword(s):  
Star Formation ◽  
Gas Dynamics ◽  
Equal Mass ◽  
Interacting Galaxies ◽  
Ionized Gas ◽  
Star Forming ◽  
Gas Kinematics ◽  
Fabry Perot ◽  
Different Types

AbstractWe present scanning Fabry-Perot observations of different types of star-forming galaxies from apparently isolated LIRGs to equal mass interacting galaxies. We analyze the ionized gas kinematics, its relation with the morphology of each system and the location of SF regions for different systems.

scholarly journals Outflows in nearby AGNs

2009 ◽  
Vol 5 (H15) ◽  
pp. 245-246
Author(s):  
Thaisa Storchi-Bergmann
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Gas Kinematics ◽  
Integral Field Spectroscopy ◽  
Line Region ◽  
Mass Outflow ◽  
Kinematic Studies ◽  
Narrow Line Region ◽  
Integral Field ◽  
Velocity Channel

AbstractI report results of kinematic studies of the Narrow-Line Region (NLR) of nearby Active Galactic Nuclei (AGN) from integral field spectroscopy (IFS) obtained with the Gemini Telescopes, including mass outflow rates and corresponding kinetic power. The IFS has allowed the construction of velocity channel maps which provide a better coverage of the gas kinematics and do not support the presence of acceleration up to hundred parsec scales in the NLR as found in previous studies based solely on centroid velocity maps.

scholarly journals The PDR structure and kinematics around the compact H ii regions S235 A and S235 C with [C ii], [13C ii], [O i], and HCO+ line profiles

2020 ◽  
Vol 497 (3) ◽  
pp. 2651-2669
Author(s):  
M S Kirsanova ◽  
V Ossenkopf-Okada ◽  
L D Anderson ◽  
P A Boley ◽  
J H Bieging ◽  
...  
Keyword(s):  
Optical Depth ◽  
Molecular Layer ◽  
Line Emission ◽  
H Ii Regions ◽  
Line Profiles ◽  
Gas Kinematics ◽  
Spherical Models ◽  
Absorbing Material ◽  
H Ii Region ◽  
Integrated Intensities

ABSTRACT The aim of this work is to study structure and gas kinematics in the photodissociation regions (PDRs) around the compact H ii regions S235 A and S235 C. We observe the [C ii], [13C ii], and [O i] line emission, using SOFIA/upGREAT, and complement them by data of HCO+ and CO. We use the [13C ii] line to measure the optical depth of the [C ii] emission, and find that the [C ii] line profiles are influenced by self-absorption, while the [13C ii] line remains unaffected by these effects. Hence, for dense PDRs, [13C ii] emission is a better tracer of gas kinematics. The optical depth of the [C ii] line is up to 10 in S235 A. We find an expanding motion of the [C ii]-emitting layer of the PDRs into the front molecular layer in both regions. Comparison of the gas and dust columns shows that gas components visible neither in the [C ii] nor in low-J CO lines may contribute to the total column across S235 A. We test whether the observed properties of the PDRs match the predictions of spherical models of expanding H ii region + PDR + molecular cloud. Integrated intensities of the [13C ii], [C ii], and [O i] lines are well represented by the model, but the models do not reproduce the double-peaked [C ii] line profiles due to an insufficient column density of C+. The model predicts that the [O i] line could be a more reliable tracer of gas kinematics, but the foreground self-absorbing material does not allow using it in the considered regions.

scholarly journals The Formation of Stellar Galactic Nuclei through Dissipative Gas Dynamics

2007 ◽  
Vol 24 (2) ◽  
pp. 77-94 ◽  
Author(s):  
K. Bekki
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Gas Dynamics ◽  
Gravitational Instability ◽  
Numerical Study ◽  
Galactic Nuclei ◽  
Threshold Value ◽  
Model Parameters ◽  
Host Galaxies ◽  
Chemical Enrichment

AbstractIt is a long-standing and remarkable problem as to howstellar galactic nuclei (SGN) were formed in the central region of galaxies. In order to elucidate the formation processes of SGN, we numerically investigate gas dynamics, star formation, and chemical evolution in the central 1–1000 pc of gas disks embedded by galactic stellar spheroids. The main results of the present numerical study are: (a) SGN can be formed from dissipative, repeated merging of massive stellar and gaseous clumps that have typical masses of 105–106 M⊙ and are developed from nuclear gaseous spiral arms owing to local gravitational instability. Typically ∼5% of the masses of their host spheroids can be transfered to the central∼50 pc and thus become SGN. (b) SGN have very flattened shapes, and rotational kinematics and central velocity dispersions much smaller than those of their host spheroids. These structural and kinematic characteristics do not depend on model parameters such as masses of spheroids (Msph) and initial gas mass fraction (fg). (c) Stellar populations of SGN can show a wide rage of ages and metallicities, because SGN are formed from massive clumps with different star-formation and chemical-evolution histories. The mean metallicities of SGN can be significantly higher than those of their host spheroids. (d) More massive, higher density SGN can be formed in spheroids with higher surface brightness. Furthermore there can be a threshold value (∼0.2) of fg below which massive SGN are less likely to be formed in the central gas disks of spheroids. (e) More massive spheroids can have more massive, more metal-rich and higher-density SGN, because star formation and chemical enrichment proceed more efficiently owing to the less dramatic suppression of star formation by supernovae feedback effects in more massive spheroids.Based on these results, we discuss correlations between the physical properties of SGN and those of their host galaxies, structural and kinematic properties of SGN of dwarf elliptical galaxies and the origin of very massive star clusters such as ω Cen and ultra-compact dwarf galaxies.

scholarly journals Cluster formation in the W 40 and Serpens South complex triggered by the expanding H ii region

2018 ◽  
Vol 71 (Supplement_1) ◽  
Author(s):  
Tomomi Shimoikura ◽  
Kazuhito Dobashi ◽  
Fumitaka Nakamura ◽  
Yoshito Shimajiri ◽  
Koji Sugitani
Keyword(s):  
Cluster Formation ◽  
Three Dimensional ◽  
Outer Shell ◽  
Emission Lines ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Large Area ◽  
Dark Cloud ◽  
H Ii Region ◽  
Expanding Shells

Abstract We present the results of mapping observations covering a large area of 1 square degree around W 40 and Serpens South carried out in the 12CO (J = 1–0), 13CO (J = 1–0), C18O (J = 1–0), CCS (JN = 87–76), and N2H+ (J = 1–0) emission lines with the 45 m Nobeyama Radio Telescope. W 40 is a blistered H ii region, and Serpens South is an infrared dark cloud accompanied by a young cluster. The relation between these two regions, which are separated by ∼20′ on the sky, has not been recognizable so far. We found the C18O emission is distributed smoothly throughout the W 40 and Serpens South regions, and that the two regions seem to be physically connected. We divided the C18O emission into four groups in terms of the spatial distributions around the H ii region which we call 5, 6, 7, and 8 km s−1 components according to their typical LSR velocity, and propose a three-dimensional model of the W 40 and Serpens South complex. We found two elliptical structures in the position–velocity diagrams, which can be explained as part of two expanding shells. One of the shells is small inner shell just around the H ii region, and the other is a large outer shell corresponding to the boundary of the H ii region. Dense gas associated with the young cluster of Serpens South is likely to be located at the surface of the outer shell, indicating that the natal clump of the young cluster is interacting with the outer shell being compressed by the expansion of the shell. We suggest that the expansion of the shell induced the formation of the young cluster.

scholarly journals Streaming Motions in the Local Universe

1992 ◽  
Vol 9 ◽  
pp. 687-691
Author(s):  
Ofer Lahav
Keyword(s):  
Total Mass ◽  
Cold Dark Matter ◽  
Local Group ◽  
Spiral Galaxies ◽  
Background Radiation ◽  
Gravitational Instability ◽  
Cosmic Background Radiation ◽  
Local Universe ◽  
Cosmic Background ◽  
Hubble Flow

AbstractDeviations from the Hubble flow directly probe of the underlying total mass distribution, assuming the gravitational instability picture. We discuss the origin of motion of the Local Group with respect to the Cosmic Background Radiation and review the peculiar velocity field deduced from distances to hundreds of elliptical and spiral galaxies, including new results for the Shapley Supercluster. Bulk-flow solutions which are free of Malmquistbias are presented, indicating coherence length larger than that expected from the optical and IRAS dipoles or from Cold Dark Matter models.

scholarly journals Molecular Hydrogen Emission from Cold Condensations in NGC 2440

1989 ◽  
Vol 131 ◽  
pp. 207-207
Author(s):  
N. K. Reay ◽  
N. A. Walton ◽  
P. D. Atherton
Keyword(s):  
Planetary Nebula ◽  
Molecular Hydrogen ◽  
Total Mass ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Line Emission ◽  
Central Star ◽  
Hydrogen Emission ◽  
H Ii Region ◽  
Hydrogen Mass

We report observations of the v = 1-0 S(1) line of molecular hydrogen in the high excitation Planetary Nebula NGC 2440. The emission is particularly strong at the positions of the two bright condensations which lie well within the H II region and close to the position of the very hot T = 350,000 K central star. The emission is consistent with an excited molecular hydrogen mass of 2–4 × 10−5 M⊙ in the condensations, and we estimate the total mass of excited molecular hydrogen associated with the H II region to be 6 × 10−3 M⊙. We show that the radiation pressure from the central star is insufficient to excite the S(1) line emission. We also show that a stellar wind driven shock would imply a mass loss rate of 3 × 10−7 M⊙ yr−1 if we adopt a wind velocity of 2000 km s−1.

scholarly journals Ring nebulae: what they tell us about Wolf-Rayet stars

1999 ◽  
Vol 193 ◽  
pp. 306-315 ◽  
Author(s):  
Anthony P. Marston
Keyword(s):  
Mass Loss ◽  
Total Mass ◽  
Massive Stars ◽  
Gas Kinematics ◽  
Total Mass Loss ◽  
Neutral Gas ◽  
History Of ◽  
Complex Forms ◽  
Ring Nebulae ◽  
Loss Rates

The environments of evolved massive stars provide an opportunity of obtaining information on the past, as well as current, condition of the stars themselves. In this review we will look at the incidence of ring nebulae around Wolf-Rayet stars, their differing morphologies at various wavelengths and the existence of multiple, concentric shells. We use this information to show that WRs are indeed evolved stars and that the various phases of evolution for a WR star are evidenced in their environments. Abundance measurements and kinematics show that complex forms of mass ejection are likely to have occurred in the evolution of WR stars providing clumpy structures of dust, and both ionized and neutral gas. Gas kinematics also provide estimates to the time-scales of each of the evolutionary phases of WR stars, which can be combined with estimates of nebular masses to provide the approximate values for such crucial parameters as total mass-loss and historical mass-loss rates. Overall, it is illustrated that studies of the environments of WR stars have the potential to provide important information about the mass-loss history of very massive stars, including estimates of the time period of each mass-loss phase, typical mass loss rates, total mass lost and likely evolutionary path. Some of the remaining problems relating to the use of ring nebulae as probes to the evolutionary history of WR stars are also discussed.

scholarly journals The Stellar Cluster

1989 ◽  
Vol 136 ◽  
pp. 477-486 ◽  
Author(s):  
K. Sellgren
Keyword(s):  
Mass Distribution ◽  
Total Mass ◽  
Galactic Center ◽  
Current Debate ◽  
Core Radius ◽  
Stellar Cluster ◽  
Mass Distributions ◽  
The Core ◽  
Gas Kinematics ◽  
The Galaxy

Observations of the stellar cluster in the central 10 pc of the Galaxy are reviewed. The stellar density law derived from the observed light distribution and the effects on this density law of variable extinction, the possibility of a varying mass-to-light ratio, and the current debate as to the core radius of the cluster are all important for establishing the true mass distribution of the stellar cluster. The presence of the supergiant IRS 7 in the Galactic Center establishes that some recent star formation has occurred, but the age and extent of a possible starburst are still being established. The kinematics of the stellar cluster show predominantly velocity dispersion, in contrast to the systematic gas motion observed, yet the total mass distributions derived from stellar and gas kinematics agree reasonably well. The core radius of the cluster is critical to establishing whether or not a central dark mass is required to explain the total mass distribution.

Supernovae and interstellar gas dynamics

1967 ◽  
Vol 31 ◽  
pp. 117-119
Author(s):  
F. D. Kahn ◽  
L. Woltjer
Keyword(s):  
Lower Limit ◽  
High Velocity ◽  
Gas Dynamics ◽  
Interstellar Cloud ◽  
Interstellar Gas ◽  
Random Motions ◽  
Relativistic Particles

The efficiency of the transfer of energy from supernovae into interstellar cloud motions is investigated. A lower limit of about 0·002 is obtained, but values near 0·01 are more likely. Taking all uncertainties in the theory and observations into account, the energy per supernova, in the form of relativistic particles or high-velocity matter, needed to maintain the random motions in the interstellar gas is estimated as 1051·4±1ergs.

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