scholarly journals Photometry and Kinematics of the Ringed Barred Galaxy NGC 3081

1996 ◽  
Vol 157 ◽  
pp. 244-246
Author(s):  
Guy B. Purcell ◽  
R. Buta
Keyword(s):  
Velocity Field ◽  
Preliminary Analysis ◽  
Fabry Perot ◽  
The Galaxy ◽  
Pattern Speed

AbstractWe present a preliminary analysis of B- and I-band CCD images and Rutgers imaging Fabry–Perot Hα interferometry of the galaxy NGC 3081. We find that the outer R1 and inner ring are both intrinsically oval. We derive a bar pattern speed from the velocity field.

scholarly journals Fabry-Perot Observations and Hydrodynamical Simulations of the Barred Spiral NGC 4123

1996 ◽  
Vol 157 ◽  
pp. 489-491 ◽  
Author(s):  
Benjamin J. Weiner ◽  
J. A. Sellwood ◽  
T. B. Williams
Keyword(s):  
Velocity Field ◽  
Gas Flow ◽  
Semimajor Axis ◽  
Lagrange Point ◽  
Model Potentials ◽  
Fabry Perot ◽  
Correct Alignment ◽  
Pattern Speed ◽  
Leading Edges ◽  
Hydrodynamical Simulations

AbstractWe present Fabry-Perot observations of the velocity field of gas in the barred spiral NGC 4123, and 2-D hydrodynamical simulations of the gas flow in model potentials derived from I-band photometry. The simulated gas flow is quite sensitive to the details of the potential, which enables us to constrain parameters such as the M/LI of the bar and the bar pattern speed. The observations confirm that the dust lanes along the leading edges of the bar are the locations of shocks. Requiring models to produce shocks with the correct alignment constrains the Lagrange point L1 (corotation) to be at a radius 1.1 – 1.4 times the semimajor axis of the bar, i.e. the bar is a fast rotator.

scholarly journals Gas and Stellar Kinematics in the Disk and Bar of Mrk 573

1996 ◽  
Vol 157 ◽  
pp. 218-220 ◽  
Author(s):  
V. L. Afanasiev ◽  
A. N. Burenkov ◽  
A. I. Shapovalova ◽  
V. V. Vlasyuk
Keyword(s):  
Velocity Field ◽  
Complex Structure ◽  
Seyfert Galaxy ◽  
Helical Structure ◽  
Emission Lines ◽  
Stellar Kinematics ◽  
Gas Distribution ◽  
Fabry Perot ◽  
The Galaxy ◽  
Galaxy Center

AbstractResults of 3D-spectroscopy for the nearby Seyfert galaxy Mrk 573 obtained at the 6-m telescope with the scanning Fabry-Perot interferometer and the Multi-Pupil Field Spectrograph (MPFS) are presented. Emission lines images of the galaxy center demonstrate a complex structure of ENLR, coinciding with the radio data. An analysis of the velocity field shows that some gas structures do not lie in the plane of the galaxy. An explanation of the observed velocity field and gas distribution by radiation of a helical structure located inside an ionization cone is proposed.

scholarly journals 2D kinematics of the edge-on spiral galaxy ESO 379-006

2012 ◽  
Vol 8 (S295) ◽  
pp. 234-235
Author(s):  
M. Rosado ◽  
R. F. Gabbasov ◽  
P. Repetto ◽  
I. Fuentes-Carrera ◽  
P. Amram ◽  
...  
Keyword(s):  
Velocity Field ◽  
Radial Velocity ◽  
Rotation Curve ◽  
Minor Axis ◽  
Ionized Gas ◽  
Diffuse Ionized Gas ◽  
Fabry Perot ◽  
The Galaxy ◽  
Rotation Motion

AbstractWe present a kinematical study of the marginally edge-on galaxy ESO 379-006. With Fabry-Perot spectroscopy at Hα we obtain velocity maps, the radial velocity field, and position-velocity diagrams parallel to the major and to the minor axis of the galaxy. We build the rotation curve of the galaxy and discuss the role of projection effects. The twisting of isovelocities in the radial velocity field of the disk of ESO 379-006 as well as a kinematical asymmetry found in the position-velocity diagrams parallel to the minor axis suggest the existence of non-circular motions that can be modeled by including a radial inflow besides the rotation motion. Extraplanar Diffuse Ionized gas was detected in this galaxy both from the images and from its kinematics. It is possible that the diffuse gas is lagging in rotation.

Comments on the reconnexion rate of magnetic fields

1973 ◽  
Vol 9 (1) ◽  
pp. 49-63 ◽  
Author(s):  
E. N. Parker
Keyword(s):  
Velocity Field ◽  
Magnetic Fields ◽  
Turbulent Flows ◽  
Similarity Solutions ◽  
Neutral Point ◽  
Solar Photosphere ◽  
Complete Field ◽  
Fluid Equations ◽  
The Galaxy

The reconnexion rate of magnetic fields is crucial in understanding the fields found in turbulent flows in the solar photosphere and in the galaxy, and in flare phenomena. This paper examines the behaviour of magnetic fields in the neighbourhood of an X-type neutral point. The treatment is kinematical, specifying the velocity field v and constructing solutions to the hydromagnetic equation for B. The calculations demonstrate that the reconnexion rate is controlled by the diffusion in the near neighbourhood of the neutral point, and is not arbitrarily large, as has been suggested by similarity solutions of the complete field and fluid equations for vanishing diffusion

scholarly journals The Velocity Field of S308. The Ring Nebula Around the WN5 Star HD 50896

1982 ◽  
Vol 99 ◽  
pp. 305-309
Author(s):  
Paris Pişmiş ◽  
Alfonso Quintero
Keyword(s):  
Velocity Field ◽  
Radial Velocities ◽  
Expansion Velocity ◽  
Ring Nebula ◽  
Fabry Perot

Radial velocities are determined by Fabry-Pérot interferometry at 131 points of the ring nebula S308. The velocities have yielded a kinematic distance of 1.5 kpc for the object, and an expansion velocity of 45–60 km s−1. The ring nebula has a diameter of 13 pc and the age is estimated to be about 1.5 to 2×105 years.

scholarly journals On a mechanism that structures galaxies

1979 ◽  
Vol 84 ◽  
pp. 157-158
Author(s):  
D. Lynden-Bell
Keyword(s):  
Angular Momentum ◽  
Differential Rotation ◽  
Spiral Structure ◽  
Rotation Curves ◽  
Eccentric Orbits ◽  
The Galaxy ◽  
Central Regions ◽  
Pattern Speed ◽  
Stellar Orbit ◽  
Lindblad Resonance

By considering the interaction of a single stellar orbit with a weak cos 2Φ potential it is shown that in the central regions of galaxies with slowly rising rotation curves, the elongations of the orbits will align along any potential valley and oscillate about it. This effect is more pronounced for elongated orbits. In such regions any pair of orbits will naturally align under their mutual gravity and so a bar will form. The gravity of this bar will drive a spiral structure in the outer parts of the galaxy where differential rotation is too strong to allow the orbits to be caught by the bar. The spiral structure carries a torque which slowly drains angular momentum from the bar, gradually making its outline more eccentric and slowing its pattern speed. In the outer parts of the bar only the more eccentric orbits align with the potential valley; the rounder ones form a ring or lens about the bar. As the pattern speed slows down, the corotation resonance and outer Lindblad resonance, which receive the angular momentun, move outwards. The evolution of the system is eventually slowed down by the weakness of these outer resonances where the material is rather sparse.

Kinematic asymmetry of galaxy pairs

2019 ◽  
Vol 14 (S353) ◽  
pp. 262-263
Author(s):  
Shuai Feng ◽  
Shi-Yin Shen ◽  
Fang-Ting Yuan
Keyword(s):  
Star Formation ◽  
Velocity Field ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Control Sample ◽  
Interacting Galaxies ◽  
Ionized Gas ◽  
Galaxy Interaction ◽  
The Galaxy

AbstractThe interaction between galaxies is believed to be the main origin of the peculiarities of galaxies. It can disturb not only the morphology but also the kinematics of galaxies. These disturbed and asymmetric features are the indicators of galaxy interaction. We study the velocity field of ionized gas in galaxy pairs based on MaNGA survey. Using the kinemetry package, we fit the velocity field and quantify the degree of kinematic asymmetry. We find that the fraction of high kinematic asymmetry is much higher for galaxy pairs with dp⩽30h−1kpc. Moreover, compared to a control sample of single galaxies, we find that the star formation rate is enhanced in paired galaxies with high kinematic asymmetry. For paired galaxies with low kinematic asymmetry, no significant SFR enhancement has been found. The galaxy pairs with high kinematic asymmetry are more likely to be real interacting galaxies rather than projected pairs.

scholarly journals Modelling the Structure of the Ringed Spiral NGC 4736

1996 ◽  
Vol 157 ◽  
pp. 253-255
Author(s):  
Wim van Driel ◽  
Pieter Mulder ◽  
Françoise Combes
Keyword(s):  
Mass Distribution ◽  
Spiral Structure ◽  
Optical Spectra ◽  
Spectral Lines ◽  
Time Interval ◽  
Limited Time ◽  
The Galaxy ◽  
Dynamical Simulations ◽  
Pattern Speed ◽  
Limited Time Interval

AbstractWe studied the ringed RSab(r)-type spiral NGC 4736, which has a probably slightly oval disk and a very small bar. We mapped the galaxy in the HI and Hα spectral lines and we obtained long-slit optical spectra. These data were modeled using a 2-D gas dynamical code. The 2-D potential used is axisymmetric in the inner and outer regions and oval (b/a=0.8) at intermediate radii only. The oval component rotates at a pattern speed of 40 km s–1 kpc–1, close to the observed value. Inner and outer rings, like those observed, form at the inner and outer Lindblad resonances, though they co-exist only during a limited time interval in the simulations. The morphology and kinematics of the inner ring and spiral structure as observed in neutral and ionized hydrogen can be well understood in terms of gas dynamical simulations, given the form of the (stellar) potential. What remains to be explained is the origin of the nonaxisymmetric features in the mass distribution defining the potential.

scholarly journals 7.15. The Fourier analysis of the observed velocity field of gas in the inner 1.5 pc of the Galaxy

1998 ◽  
Vol 184 ◽  
pp. 321-324
Author(s):  
A.M. Fridman ◽  
V.V. Lyakhovich ◽  
O.V. Khoruzhii ◽  
O.K. Silchenko
Keyword(s):  
Velocity Field ◽  
Fourier Analysis ◽  
Galactic Center ◽  
Second Harmonic ◽  
Density Wave ◽  
Ionized Gas ◽  
Density Maximum ◽  
Fourier Harmonic ◽  
Wave Nature ◽  
The Galaxy

The Fourier analysis of the observed velocity field of ionized gas in the inner 1.5 pc of the Galactic Center (obtained by Roberts and Goss, 1993) is made. As follows from the analysis, the observed field of residual velocities is dominated by the second Fourier harmonic. This fact can be treated as a consequence of the presence of an one-armed density wave with the density maximum along the Northern Arm plus the Western Arc structure. The wave nature of this structure is proved on the base of the behaviour of the phase of the second harmonic of line-of-sight velocity field in the whole region. The Fourier analysis shows also the presence of systematic radial velocity. We consider this flow as a quasi-stationary radial drift caused by one-armed nonlinear density wave (‘mini-spiral’).

scholarly journals The velocity field of the Lyra complex

2020 ◽  
Vol 633 ◽  
pp. A108 ◽  
Author(s):  
M. Girardi ◽  
W. Boschin ◽  
S. De Grandi ◽  
M. Longhetti ◽  
S. Clavico ◽  
...  
Keyword(s):  
Velocity Field ◽  
High Velocity ◽  
Major Axis ◽  
Dynamical Analysis ◽  
Cluster Assembly ◽  
X Ray ◽  
Radio Data ◽  
The Galaxy ◽  
A Minor ◽  
Complex Scenario

Context. The formation of cosmic structures culminates with the assembly of galaxy clusters, a process that is quite different from cluster to cluster. Aims. We present the study of the structure and dynamics of the Lyra complex, consisting of the two clusters RXC J1825.3+3026 and CIZA J1824.1+3029, which was very recently studied by using both X-ray and radio data. Methods. This is the first analysis based on the kinematics of member galaxies. New spectroscopic data for 285 galaxies were acquired at the Italian Telescopio Nazionale Galileo and were used in combination with PanSTARRS photometry. The result of our member selection is a sample of 198 galaxies. Results. For RXCJ1825 and CIZAJ1824 we report the redshifts, z = 0.0645 and z = 0.0708, the first estimates of velocity dispersion, σv = 995+131−125 km s−1 and σv = 700 ± 50 km s−1, and of dynamical mass, M200 = 1.1 ± 0.4  × 1015 M⊙ and M200 = 4 ± 0.1 × 1014 M⊙. The past assembly of RXCJ1825 is traced by the two dominant galaxies, which are both aligned with the major axis of the galaxy distribution along the east–west direction, and by a minor northeast substructure. We also detect a quite peculiar high velocity field in the southwest region of the Lyra complex. This feature is likely related to a very luminous galaxy, which is characterized by a high velocity. This galaxy is suggested to be the central galaxy of a group that is in interaction with RXCJ1825 according to very recent studies based on X-ray and radio data. The redshift of the whole Lyra complex is z = 0.067. Assuming that the redshift difference between RXCJ1825 and CIZAJ1824 is due to the relative kinematics, the projected distance between the cluster centers is D ∼ 1.3 Mpc and the line–of–sight velocity difference is ∼1750 km s−1. A dynamical analysis of the system shows that the two clusters are likely to be gravitationally bound in a pre-merger phase, and that CIZAJ1824 is moving toward RXCJ1825. Conclusions. Our results corroborate a picture where the Lyra region is the place of a very complex scenario of cluster assembly.

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