scholarly journals Compact Array Mapping of the Nuclear Starburst in NGC 7552

1994 ◽  
Vol 158 ◽  
pp. 355-357
Author(s):  
Duncan A. Forbes ◽  
Ray P. Norris ◽  
Gerry M. Williger ◽  
R. Chris Smith
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Starburst Galaxy ◽  
Angular Momenta ◽  
Lindblad Resonance ◽  
Inner Lindblad Resonance ◽  
Compact Array

We discuss new observations of the starburst galaxy NGC 7552. From optical and near–infrared colour maps we find a red, dusty circumnuclear ring. High-resolution radio mapping from the ATCA reveals the same ring, and a number of bright blobs (probably SNRs). The ring is probably associated with gas and dust which have lost angular momenta due to torques in the bar potential and settled at the inner Lindblad resonance. These circumnuclear starburst rings may be relatively common (when mapped without the obscuring affects of dust) and may play a role in collimating material of a nuclear outflow.

scholarly journals The shearing sheet and swing amplification revisited

2020 ◽  
Vol 496 (1) ◽  
pp. 767-783
Author(s):  
James Binney
Keyword(s):  
Dispersion Relation ◽  
Narrow Range ◽  
Real Space ◽  
Angular Momenta ◽  
Limited Life ◽  
Quantitative Understanding ◽  
The Impact ◽  
Axisymmetric Disturbances ◽  
Lindblad Resonance ◽  
Inner Lindblad Resonance

ABSTRACT The principal results of the classic analysis of the shearing sheet and swing amplification by Julian and Toomre (JT) are re-derived in a more accessible way and used to gain a better quantitative understanding of the dynamics of stellar discs. The axisymmetric limit of the shearing sheet is derived and used to re-derive Kalnajs’ 1965 dispersion relation and Toomre’s 1964 stability criterion for axisymmetric disturbances. Using the shearing sheet to revisit Toomre’s important 1969 paper on the group velocity implied by the Lin–Shu–Kalnajs (LSK) dispersion relation, we discover that two wavepackets emerge inside corotation: one each side of the inner Lindblad resonance. An extended form of the JT equation is used to investigate the impact of there being a deficit or surplus of stars in a narrow range of angular momenta. Swing amplification of leading waves introduced by such a groove gives rise to transient trailing spirals that extend further in radius and live longer at smaller azimuthal wavenumbers. Although the LSK dispersion relation provides useful interpretations of wavepackets, the shearing sheet highlights the limitations of the LSK approach to disc dynamics. Disturbances do not avoid an annulus around corotation, as the LSK dispersion relation implies. While disturbances of the shearing sheet have a limited life in real space, they live on much longer in velocity space, which Gaia allows us to probe extensively. c++ code is provided to facilitate applications of winding spiral waves.

Molecular Gas in the Centers of Barred and Starburst Galaxies

1994 ◽  
Vol 140 ◽  
pp. 282-292
Author(s):  
Jeffrey D. P. Kenney
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Starburst Galaxy ◽  
Molecular Gas ◽  
Barred Galaxies ◽  
Twin Peaks ◽  
Ngc 1068 ◽  
Lindblad Resonance ◽  
Inner Lindblad Resonance ◽  
Co Emission

AbstractHigh resolution interferometric CO maps of the circumnuclear regions of several barred galaxies show intense CO emission arising from twin peaks, which are oriented perpendicular to the large-scale stellar bars and located where dust lanes intersect nuclear rings of HII regions. These twin gas concentrations can be explained by the crowding of gas streamlines near stellar inner Lindblad resonances. In the barred nuclear starburst galaxy NGC 3504, a large concentration of molecular gas is centered on the nucleus, apparently inside an inner Lindblad resonance. Star formation is consuming the gas most rapidly where the rotation curve is nearly solid body, suggesting that tidal shear helps control the rate of star formation. A comparison with M82 and NGC 1068 suggests that the starburst in NGC 3504 is in an early phase of its evolution, and that starburst evolution is strongly influenced by shear.

scholarly journals M100 and NGC 6951: Morphological Clues to Central Dynamics

1996 ◽  
Vol 157 ◽  
pp. 416-419
Author(s):  
J. H. Knapen ◽  
I. Shlosman ◽  
J. E. Beckman ◽  
C. H. Heller ◽  
R. F. Peletier ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
High Resolution ◽  
Dynamical Model ◽  
Nuclear Region ◽  
Star Forming ◽  
Lindblad Resonance ◽  
Inner Lindblad Resonance ◽  
Band Image

AbstractHigh-resolution optical and NIR observations are used to constrain a dynamical model of the circumnuclear star forming (SF) region in the barred galaxy M100 (NGC 4321). Small leading arms observed in our K-band image of the nuclear region have been reproduced in numerical modeling of M100, a galaxy with a double inner Lindblad resonance (ILR). We also present preliminary optical and NIR observations of NGC 6951: a barred galaxy with circumnuclear SF showing a distinctly different behavior to M100 at 2.2µm.

scholarly journals Star Clusters in Galactic Resonance Rings

2002 ◽  
Vol 207 ◽  
pp. 447-449
Author(s):  
R. Buta
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Hubble Space Telescope ◽  
Star Clusters ◽  
Disk Galaxies ◽  
Wide Field ◽  
Space Telescope ◽  
Lindblad Resonance ◽  
Inner Lindblad Resonance

Resonance rings are intriguing sites of organized star formation in some galaxies. The Hubble Space Telescope Wide Field and Planetary Camera 2 has been used to image several resonance rings at high resolution in order to study the star clusters in the rings. Here I summarize results on inner Lindblad resonance rings in ESO 565–11 and NGC 1326, and on an inner 4:1 resonance ring in the Seyfert 2 galaxy NGC 3081. The latter ring provides one of the strongest cases illustrating the connection between star formation and dynamics in disk galaxies.

scholarly journals A SINFONI view of circum-nuclear star-forming rings in spiral galaxies

2007 ◽  
Vol 3 (S245) ◽  
pp. 177-180 ◽  
Author(s):  
Jesús Falcón-Barroso ◽  
Torsten Böker ◽  
Eva Schinnerer ◽  
Johan H. Knapen ◽  
Stuart Ryder
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Spiral Galaxies ◽  
Major Axis ◽  
Emission Lines ◽  
Stellar Clusters ◽  
Star Forming ◽  
Integral Field ◽  
Lindblad Resonance ◽  
Inner Lindblad Resonance

AbstractWe present near-infrared (H- and K-band) SINFONI integral-field observations of the circumnuclear star formation rings in five nearby spiral galaxies. We made use of the relative intensities of different emission lines (i.e. [FeII], HeI, Brγ) to age date the stellar clusters present along the rings. This qualitative, yet robust, method allows us to discriminate between two distinct scenarios that describe how star formation progresses along the rings. Our findings favour a model where star formation is triggered predominantly at the intersection between the bar major axis and the inner Lindblad resonance and then passively evolves as the clusters rotate around the ring (‘Pearls on a string’ scenario), although models of stochastically distributed star formation (‘Popcorn’ model) cannot be completely ruled out.

scholarly journals New HI Observations of the prototype Polar Ring Galaxy NGC 4650A

1997 ◽  
Vol 14 (1) ◽  
pp. 92-95
Author(s):  
Magda Arnaboldi
Keyword(s):  
High Resolution ◽  
Velocity Field ◽  
Central Region ◽  
Near Infrared ◽  
New Technology ◽  
Host Galaxy ◽  
Polar Structure ◽  
Polar Ring ◽  
Compact Array ◽  
Band Image

AbstractNew, high-resolution observations of the HI emission line and 20 cm continuum at the Australia Telescope Compact Array (ATCA) for the prototype polar ring galaxy NGC 4650A are presented. They show the presence of a far more extended HI distribution than previously observed with the VLA, and a very regular velocity field out to a distance of ∼50 kpc. The combined analysis of the HI data with optical and near-infrared (NIR) images argues against previous warp models used to describe the dynamics of this object. Further analysis of the new B-band image obtained at the European Southern Observatories New Technology Telescope (NTT) indicates clearly that the polar structure extends continuously to within about 200 pc of the nucleus of the central host galaxy, ruling out the presence of a ‘hole’ in the central region of this component. The presence of two spiral arms stretching out in the polar disk seems to represent the most likely explanation for the observed morphology and kinematics.

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