Abstract
view Abstract Citations (53) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Hydrodynamic Models of the Cartwheel Ring Galaxy Struck-Marcell, Curtis ; Higdon, James L. Abstract The wealth of new data on the Cartwheel ring galaxy acquired in the last decade provides new opportunities to test the collisional model for its formation and examine the star formation processes in this unique environment. A series of increasingly sophisticated models of the Cartwheel are studied in this paper. First, it is shown that given a potential derived from the new 21 cm rotation curve, even a simple analytic model of the postcollision kinematics can reproduce many of the specific morphological features. With this potential, numerical restricted three-body simulations can reproduce the asymmetric morphology in detail as the result of a slightly off-center collision. Since the observations indicate that most of the Cartwheel disk is gas-dominated, these calculations were also carried out with the gas dynamics simulated by a Smooth Particle Hydrodynamics algorithm. As expected, a strong shock forms at the location of the inner ring. Model velocity fields are found to be in general agreement with the kinematical information available from observation, though these are still of relatively low spatial resolution. The models suggest a possible resolution of the different values of the ring expansion velocity derived from optical and radio data, as a result of different azimuthal weightings in the slightly asymmetric wave. Simulations including a calculation of local self- gravity in the disk were carried out in cases where the gas surface density is initially close, but slightly below, the threshold for gravitational instability. In such cases the ring compression pushes the gas above threshold temporarily, relatively dense knots are amplified, and spoke-like features appear behind the ring. The number and spacing of the knots and spokes depend on the scale of the instability. Assuming star formation occurs in the local density enhancements, almost all of the large-scale morphology and kinematics of the Cartwheel can be accounted for by the collisionally triggered gravitational instability. The paper concludes with a discussion of the ramifications of the Cartwheel results for various phenomenological models of star formation in interacting galaxies. Publication: The Astrophysical Journal Pub Date: July 1993 DOI: 10.1086/172811 Bibcode: 1993ApJ...411..108S Keywords: Astronomical Models; Galactic Evolution; Hydrodynamics; Interacting Galaxies; Ring Galaxies; H Ii Regions; Morphology; Spatial Resolution; Star Formation; Astrophysics; GALAXIES: FORMATION; GALAXIES: INDIVIDUAL ALPHANUMERIC: A0035-335; GALAXIES: INTERACTIONS; GALAXIES: KINEMATICS AND DYNAMICS; HYDRODYNAMICS full text sources ADS | data products SIMBAD (1) NED (1)
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