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Search Results: 1 - 10 of 75 matches for " Ivanio Puerari "
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A Morphological Method to Determine Co-Rotation Radii in Spiral Galaxies
Ivanio Puerari,Horacio Dottori
Physics , 1996, DOI: 10.1086/310502
Abstract: Shock induced star formation in a stellar density wave scenario produces an azimuthal gradient of ages across the spiral arms which has opposite signs on either side of the corotation resonance (CR). We present a method based on the Fourier analysis of azimuthal profiles, to locate the CR and determine the arm character (trailing or leading) in spiral galaxies. Basically, we compare the behavior of the phase angle of the two-armed spiral in blue and infrared colors which pick out respectively young and older disk stellar population. We illustrate the method using theoretical leading and trailing, spirals. We have also applied the method to the spiral galaxies NGC 7479, for which we confirm the reported leading arms, and NGC 1832. In these galaxies we find two and three CRs respectively.
Toward a dust penetrated classification of the evolved stellar Population II disks of galaxies
David L. Block,Ivanio Puerari
Physics , 1998,
Abstract: (abridged): To derive a coherent physical framework for the excitation of spiral structure in galaxies, one must consider the co-existence of two different dynamical components: a gas-dominated Population I disk (OB associations, HII regions, cold interstellar HI gas) and an evolved stellar Population II component. The Hubble classification scheme has as its focus, the morphology of the Population I component only. In the near-infrared, the morphology of evolved stellar disks indicates a simple classification scheme: the dominant Fourier m-mode in the dust penetrated regime, and the associated pitch angle. On the basis of deprojected K$'$ (2.1$\mu m$) images, we propose that the evolved stellar disks may be grouped into three principal dust penetrated archetypes: those with tightly wound stellar arms characterised by pitch angles at K$'$ of $\sim$ 10$^{\circ}$ (the $\alpha$ class), an intermediate group with pitch angles of $\sim$ 25$^{\circ}$ (the $\beta$ class) and thirdly, those with open spirals demarcated by pitch angles at K$'$ of $\sim$ 40$^{\circ}$ (the $\gamma$ bin). Both optically flocculent or grand design galaxies can reside within the {\it same} dust penetrated morphological bin. Any specific dust penetrated archetype may be the resident disk of {\it both} an early or late type galaxy in the optical regime. There is no correlation between our dust penetrated classes and optical Hubble binning; the Hubble tuning fork does not constrain the morphology of the old stellar Population II disks.
Color Correlations in (S+S) Binary Galaxies I. The Holmberg Effect
Hector Hernandez Toledo,Ivanio Puerari
Physics , 2000,
Abstract: Relying on his photometry of galaxies, Holmberg (1958) found, more than 40 years ago, that the color indices of paired galaxies were closely correlated. Our deep broad-band BVRI CCD photometry of 45 (S+S) pairs from the Karachentsev (1972) catalogue (see Hernandez Toledo and Puerari, this volume), and additional (B-V) color information from the literature (50 extra (S+S) pairs), help us to confirm the effect. This "Holmberg Effect" has long been remained unverified and not explained yet.
BVRI Surface Photometry of (S+S) Binary Galaxies
Hector Hernandez Toledo,Ivanio Puerari
Physics , 2000,
Abstract: We report the first results of our multicolour broad-band BVRI photometry for a statistically well defined sample of interacting pairs, drawn from the Catalogue of Isolated Pairs of Galaxies in the Northern Hemisphere Karachentsev (1972). At present, the details of photometric structure of disk-disk (S+S) galaxies are just beginning to be studied because of their intrinsic difficulties. We take advantage of the statistical properties of this well defined sample of interacting galaxies to try to isolate the main structural components of galaxies. Due to their environmental simplicity (compared to groups and clusters), the sample provides an unique opportunity to peform a photometric study of galaxies and their structural components in a non-equilibrium configuration. In this contribution, the first results of a deep multicolour (BVRI) photometric study of a sample of 45 (S+S) isolated pairs of galaxies is presented. Our attention is focused on the morphology and the global photometric properties (integrated magnitudes, colours and mean surface brightness profiles).
Reviewing the observational evidence against long-lived spiral arms in galaxies
Eric E. Martinez-Garcia,Ivanio Puerari
Physics , 2013,
Abstract: We review Foyle et al. (2011) previous results, by applying a Fourier intensity phases method to a nine object sample of galaxies. It was found that two of the objects (NGC 628 and NGC 5194), with strong two-arm patterns, present positive evidence for long-lived spirals. Only one of the objects (NGC 3627) shows the contrary evidence. As determined by an analysis of resolved mass maps, the rest of the objects can not be included in the analysis because they belong to flocculent and multi-arm type of spiral arms, which are not described by density wave theory.
Spiral Structure Dynamics in Pure Stellar Disk Models
Diego Valencia-Enriquez,Ivanio Puerari
Physics , 2013,
Abstract: In order to understand the physical mechanism underlying non-steady stellar spiral arms in disk galaxies we performed a series of N-body simulations with 1.2 and 8 million particles. The initial conditions were chosen to follow Kuijken-Dubinski models. In this work we present the results of a sub-sample of our simulations in which we experiment with different disk central radial velocity dispersion and the disk scale height.
On the relative orientation of binary galaxies
Ivanio Puerari,Carlos Garcia-Gomez,Antonio Garijo
Physics , 1997,
Abstract: The projected directions of the rotation axes of interacting binary disk galaxies tend to align orthogonal to each other. Sofue (1992) has suggested that this could be due to shorter merger times for galaxies with paralel spins. We show by means of N-body simulations that this suggestion is correct.
The Large Magellanic Cloud: A power spectral analysis of Spitzer images
Ivanio Puerari,David L. Block,Bruce G. Elmegreen,Frederic Bournaud
Physics , 2010, DOI: 10.1007/978-1-4419-7317-7_10
Abstract: We present a power spectral analysis of Spitzer images of the Large Magellanic Cloud. The power spectra of the FIR emission show two different power laws. At larger scales (kpc) the slope is ~ -1.6, while at smaller ones (tens to few hundreds of parsecs) the slope is steeper, with a value ~ -2.9. The break occurs at a scale around 100-200 pc. We interpret this break as the scale height of the dust disk of the LMC. We perform high resolution simulations with and without stellar feedback. Our AMR hydrodynamic simulations of model galaxies using the LMC mass and rotation curve, confirm that they have similar two-component power-laws for projected density and that the break does indeed occur at the disk thickness. Power spectral analysis of velocities betrays a single power law for in-plane components. The vertical component of the velocity shows a flat behavior for large structures and a power law similar to the in-plane velocities at small scales. The motions are highly anisotropic at large scales, with in-plane velocities being much more important than vertical ones. In contrast, at small scales, the motions become more isotropic.
Analyzing spiral structure in a galactic disk with a gaseous component
Mata-Chavez,M. Dolores,Gomez Gilberto C.,Puerari,Ivanio
Physics , 2013,
Abstract: Using GADGET2, we performed an SPH+N-body simulation of a galactic disk with stellar and gas particles. This simulation allows to compare the spiral structure in the different disk components. Also, we performed a simulation without gaseous component to explore the effects of the gas in the spiral pattern of the stars.
Determination of resonance locations in barred spiral galaxies using multiband photometry
Amber D. Sierra,Marc S. Seigar,Patrick Treuthardt,Ivanio Puerari
Physics , 2015, DOI: 10.1093/mnras/stv678
Abstract: In this paper, we apply a method identified by Puerari & Dottori (1997) to find the corotation radii (CR) in spiral galaxies. We apply our method to 57 galaxies, 17 of which have already have their CR locations determined using other methods. The method we adopted entails taking Fourier transforms along radial cuts in the u, g, r, i, and z wavebands and comparing the phase angles as a function of radius between them. The radius at which the phase angles cross indicates the location of the corotation radius. We then calculated the relative bar pattern speed, $\mathcal{R}$, and classified the bar as "fast", where $\mathcal{R} < 1.4$, slow, where $\mathcal{R} \geq 1.4$, or intermediate, where the errors on $\mathcal{R}$ are consistent with the bar being "slow" or "fast". For the 17 galaxies that had their CR locations previously measured, we found that our results were consistent with the values of $\mathcal{R}$ obtained by the computer simulations of Rautiainen, Salo & Laurikainen (2008). For the larger sample, our results indicate that 34 out of 57 galaxies (~60%) have fast bars. We discuss these results in the context of its implications for dark matter concentrations in disk galaxies. We also discuss these results in the context of different models for spiral structure in disk galaxies.
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