Appendix - Some spectroscopic observations of the interaction between a plasma wind and a dipole magnetic field

Spectroscopic studies on seeded plasma interaction with magnetic dipole fiel

Expansivity and Shadowing in Linear Dynamics

In the early 1970's Eisenberg and Hedlund investigated relationships between expansivity and spectrum of operators on Banach spaces. In this paper we establish relationships between notions of expansivity and hypercyclicity, supercyclicity, Li-Yorke chaos and shadowing. In the case that the Banach space is $c_0$ or $\ell_p$ ($1 \leq p < \infty$), we give complete characterizations of weighted shifts which satisfy various notions of expansivity. We also establish new relationships between notions of expansivity and spectrum. Moreover, we study various notions of shadowing for operators on Banach spaces. In particular, we solve a basic problem in linear dynamics by proving the existence of nonhyperbolic invertible operators with the shadowing property. This also contrasts with the expected results for nonlinear dynamics on compact manifolds, illuminating the richness of dynamics of infinite dimensional linear operators

Anisotropy of the space orientation of radio sources. I: The catalog

A catalog of the extended extragalactic radio sources consisting of 10461 objects is compiled based on the list of radio sources of the FIRST survey. A total of 1801 objects are identified with galaxies and quasars of the SDSS survey and the Veron-Veron catalog. The distribution of the position angles of the axes of radio sources from the catalog is determined, and the probability that this distribution is equiprobable is shown to be less then 10^(-7). This result implies that at Z equal to or smaller then 0.5, spatial orientation of the axes of radio sources is anisotropic at a statistically significant level.Comment: 8 pages, 7 figure

The HI Content of Compact Groups of Galaxies

The HI content of Hickson Compact Groups in the southern hemisphere is measured using data from the HI Parkes All Sky Survey (HIPASS), and dedicated observations using the narrowband filter on the Multibeam instrument on the Parkes telescope. The expected HI mass of these groups was estimated using the luminosity, diameter and morphological types of the member galaxies, calibrated from published data. Taking careful account of non-detection limits, the results show that the compact group population that has been detected by these observations has an HI content similar to that of galaxies in the reference field sample. The upper limits for the undetected groups lie within the normal range; improvement of these limits will require a large increase in sensitivity.Comment: 27 pages, 5 figures. Accepted for publication in PAS

Double Bars, Inner Disks, and Nuclear Rings in Early-Type Disk Galaxies

We present results from an imaging survey of an unbiased sample of thirty-eight early-type (S0--Sa), low-inclination, optically barred galaxies in the field. Our goal was to find and characterize central stellar and gaseous structures: secondary bars, inner disks, and nuclear rings. Bars inside bars are surprisingly common: at least one quarter of the sample galaxies (possibly as many as 40%) are double-barred, with no preference for Hubble type or the strength of the primary bar. A typical secondary bar is ~12% of the size of its primary bar and 240--750 pc in radius. We see no significant effect of secondary bars on nuclear activity. We also find kiloparsec-scale inner disks in at least 20% of our sample, almost exclusively in S0 galaxies. These disks are on average 20% the size of their host bar, and show a wider range of relative sizes than do secondary bars. Nuclear rings are present in about a third of our sample. Most are dusty, sites of current or recent star formation, or both; such rings are preferentially found in Sa galaxies. Three S0 galaxies (15% of the S0's) appear to have purely stellar nuclear rings, with no evidence for dust or recent star formation. The fact that these central stellar structures are so common indicates that the inner regions of early-type barred galaxies typically contain dynamically cool and disklike structures. This is especially true for S0 galaxies, where secondary bars, inner disks, and/or stellar nuclear rings are present at least two thirds of the time. (abridged)Comment: LaTeX, 15 pages, 7 EPS figures; to appear in The Astronomical Journal (July 2002

VV124 (UGC4879): A new transitional dwarf galaxy in the periphery of the Local Group

We present the first resolved-star photometry of VV124 (UGC4879) and find that this is the most isolated dwarf galaxy in the periphery of the Local Group. Based on imaging and spectroscopic follow up observations with the 6m BTA telescope, we resolve VV124 into 1560 stars down to the limiting magnitude levels of V~25.6 and I~23.9. The young blue stellar populations and emission gas are found near the core, but noticeably displaced from the center of the galaxy as traced by dominant evolved red stars. The mean radial velocity derived from the spectra of two Blue Supergiant stars, an HII region and unresolved continuum sources is -80+/-10 km/s. The evolved ``red tangle'' stellar populations, which contains the red giant branch (RGB), are identified at large galactocentric radii. We use the I-band luminosity function to determine the distance based on the Tip of RGB method, 1.1+/-0.1 Mpc. This is ~10 times closer than the values usually assumed in the literature, and we provide revised distance dependent parameters. From the mean (V-I) color of the RGB, we estimate the mean metallicity as [Fe/H]~-1.37 dex. Despite of its isolated location, the properties of VV124 are clearly not those of a galaxy in formation, but rather similar to a transitional dIrr/dSph type.Comment: 4 pages, submitted to MNRAS Letter

Cosmicflows-2: I-band Luminosity - HI Linewidth Calibration

In order to measure distances with minimal systematics using the correlation between galaxy luminosities and rotation rates it is necessary to adhere to a strict and tested recipe. We now derive a measure of rotation from a new characterization of the width of a neutral Hydrogen line profile. Additionally, new photometry and zero point calibration data are available. Particularly the introduction of a new linewidth parameter necessitates the reconstruction and absolute calibration of the luminosity-linewidth template. The slope of the new template is set by 267 galaxies in 13 clusters. The zero point is set by 36 galaxies with Cepheid or Tip of the Red Giant Branch distances. Tentatively, we determine H0 = 75 km s-1 Mpc-1. Distances determined using the luminosity-linewidth calibration will contribute to the distance compendium Cosmicflows-2.Comment: Accepted for publication in The Astrophysical Journal, 27 pages, 18 figure

Structure of Disk Dominated Galaxies I. Bulge/Disk Parameters, Simulations, and Secular Evolution

(Abridged) A robust analysis of galaxy structural parameters, based on the modeling of bulge and disk brightnesses in the BVRH bandpasses, is presented for 121 face-on and moderately inclined late-type spirals. Each surface brightness (SB) profile is decomposed into a sum of a generalized Sersic bulge and an exponential disk. The reliability and limitations of our bulge-to-disk (B/D) decompositions are tested with extensive simulations of galaxy brightness profiles (1D) and images (2D). Galaxy types are divided into 3 classes according to their SB profile shapes; Freeman Type-I and Type-II, and a third ``Transition'' class for galaxies whose profiles change from Type-II in the optical to Type-I in the infrared. We discuss possible interpretations of Freeman Type-II profiles. The Sersic bulge shape parameter for nearby Type-I late-type spirals shows a range between n=0.1-2 but, on average, the underlying surface density profile for the bulge and disk of these galaxies is adequately described by a double-exponential distribution. We confirm a coupling between the bulge and disk with a scale length ratio r_e/h=0.22+/-0.09, or h_bulge/h_disk=0.13+/-0.06 for late-type spirals, in agreement with recent N-body simulations of disk formation and models of secular evolution. This ratio increases from ~0.20 for late-type spirals to ~0.24 for earlier types. The similar scaling relations for early and late-type spirals suggest comparable formation and/or evolution scenarios for disk galaxies of all Hubble types.Comment: 78 pages with 23 embedded color figures + tables of galaxy structural parameters. Accepted for publication in the Astrophysical Journal. The interested reader is strongly encouraged to ignore some of the low res figures within; instead, download the high resolution version from http://www.astro.ubc.ca/people/courteau/public/macarthur02_disks.ps.g

On the Relation Between Peak Luminosity and Parent Population of Type Ia Supernovae: A New Tool for Probing the Ages of Distant Galaxies

We study the properties of Type Ia Supernovae (SNe Ia) as functions of the radial distance from their host galaxy centers. Using a sample of 62 SNe Ia with reliable luminosity, reddening, and decline rate determinations, we find no significant radial gradients of SNe Ia peak absolute magnitudes or decline rates in elliptical+S0 galaxies, suggesting that the diversity of SN properties is not related to the metallicity of their progenitors. We do find that the range in brightness and light curve width of supernovae in spiral galaxies extends to brighter, broader values. These results are interpreted as support for an age, but not metallicity, related origin of the diversity in SNe Ia. If confirmed with a larger and more accurate sample of data, the age-luminosity relation would offer a new and powerful tool to probe the ages and age gradients of stellar populations in galaxies at redshift as high as $z\sim1-2$. The absence of significant radial gradients in the peak $\rm (B-V)_0$ and $\rm (V-I)_0$ colors of SNe Ia supports the redding correction method of Phillips et al (1999). We find no radial gradient in residuals from the SN Ia luminosity-width relation, suggesting that the relation is not affected by properties of the progenitor populations and supporting the reliability of cosmological results based upon the use of SNe Ia as distance indicators.Comment: 19 pages, incl. 3 tables & 3 figures; to appear in Nov 2000 issue of Ap

Construct Validity of the Pig Intestine Model in the Simulation of Laparoscopic Urethrovesical Anastomosis

Introduction: Laparoscopic training models are increasingly important in urology to allow trainees to improve their laparoscopic skills prior to going to the operating room. For a training model to be valid, it must correlate with performance in a real case. The model must also discriminate between experienced and inexperienced subjects. [See PDF for complete abstract