763 research outputs found
SAURON Observations of Disks in Spheroids
The panoramic integral-field spectrograph SAURON is currently being used to
map the stellar kinematics, gaseous kinematics, and stellar populations of a
large number of early-type galaxies and bulges. Here, we describe SAURON
observations of cold stellar disks embedded in spheroids (NGC3384, NGC4459,
NGC4526), we illustrate the kinematics and ionization state of large-scale
gaseous disks (NGC4278, NGC7742), and we show preliminary comparisons of SAURON
data with barred galaxy N-body simulations (NGC3623).Comment: 8 pages including 5 figures. To appear in Galaxies: The Third
Dimension, eds. M. Rosado, L. Binnette, & L. Arias (ASP: San Francisco
SAURON: An Innovative Look at Early-Type Galaxies
A summary of the SAURON project and its current status is presented. SAURON
is a panoramic integral-field spectrograph designed to study the stellar
kinematics, gaseous kinematics, and stellar populations of spheroids. Here, the
sample of galaxies and its properties are described. The instrument is detailed
and its capabilities illustrated through observational examples. These includes
results on the structure of central stellar disks, the kinematics and
ionization state of gaseous disks, and the stellar populations of galaxies with
decoupled cores.Comment: 10 pages, 6 figures. To appear in "The Dynamics, Structure & History
of Galaxies", eds. G. S. Da Costa & E. M. Sadler (San Francisco: ASP).
Version with full resolution images available at
http://www.strw.leidenuniv.nl/~dynamics/Instruments/Sauron/pub_list.htm
Integrability as a consequence of discrete holomorphicity: the Z_N model
It has recently been established that imposing the condition of discrete
holomorphicity on a lattice parafermionic observable leads to the critical
Boltzmann weights in a number of lattice models. Remarkably, the solutions of
these linear equations also solve the Yang-Baxter equations. We extend this
analysis for the Z_N model by explicitly considering the condition of discrete
holomorphicity on two and three adjacent rhombi. For two rhombi this leads to a
quadratic equation in the Boltzmann weights and for three rhombi a cubic
equation. The two-rhombus equation implies the inversion relations. The
star-triangle relation follows from the three-rhombus equation. We also show
that these weights are self-dual as a consequence of discrete holomorphicity.Comment: 11 pages, 7 figures, some clarifications and a reference adde
A SAURON view of galaxies
We have measured the two-dimensional kinematics and line-strength
distributions of 72 representative nearby early-type galaxies, out to
approximately one effective radius, with our panoramic integral-field
spectrograph SAURON. The resulting maps reveal a rich variety in kinematical
structures and linestrength distributions, indicating that early-type galaxies
are more complex systems than often assumed. We are building detailed dynamical
models for these galaxies, to derive their intrinsic shape and dynamical
structure, and to determine the mass of the supermassive central black hole.
Here we focus on two examples, the compact elliptical M32 and the E3 galaxy
NGC4365. These objects represent two extreme cases: M32 has very regular
kinematics which can be represented accurately by an axisymmetric model in
which all stars rotate around the short axis, while NGC4365 is a triaxial
galaxy with a prominent kinematically decoupled core, with an inner core that
rotates about an axis that is nearly perpendicular to the rotation axis of the
main body of the galaxy. Our dynamical models for these objects demonstrate
that two-dimensional observations are essential for deriving the intrinsic
orbital structure and dark matter content of galaxies.Comment: 7 pages (3 figures, full resolution Fig. 1 available at
http://www.strw.leidenuniv.nl/~verolme/M32.ps). Contributed talk to the
Athens Workshop on Galaxies and Chaos, Theory and Observations; Proceedings
to appear in "Galaxies and Chaos", eds. G. Contopoulos and N. Vogli
Dynamical Modeling of SAURON Galaxies
We describe our program for the dynamical modeling of early-type galaxies
observed with the panoramic integral-field spectrograph SAURON. We are using
Schwarzschild's numerical orbit superposition method to reproduce in detail all
kinematical and photometric observables, and recover the intrinsic orbital
structure of the galaxies. Since catastrophes are the most prominent features
in the orbital observables, two-dimensional kinematical coverage is essential
to constrain the dynamical models.Comment: 5 pages, 4 figures, LaTeX. Published in 2003, Carnegie Observatories
Astrophysics Series, Vol. 1: Coevolution of Black Holes and Galaxies, ed. L.
C. Ho (Pasadena: Carnegie Observatories,
http://www.ociw.edu/ociw/symposia/series/symposium1/proceedings.html
OASIS High-Resolution Integral Field Spectroscopy of the SAURON Ellipticals and Lenticulars
We present a summary of high-spatial resolution follow-up observations of the
elliptical (E) and lenticular (S0) galaxies in the SAURON survey using the
OASIS integral field spectrograph. The OASIS observations explore the central
8x10" regions of these galaxies using a spatial sampling four times higher than
SAURON, often revealing previously undiscovered features. Around 75% (31/48) of
the SAURON E/S0s with central velocity dispersion >= 120 km/s were observed
with OASIS, covering well the original SAURON representative sample. We present
here an overview of this follow-up survey, and some preliminary results on
individual objects, including a previously unreported counter-rotating core in
NGC 4382; the decoupled stellar and gas velocity fields of NGC 2768; and the
strong age gradient towards the centre of NGC 3489.Comment: 4 pages, 5 figures. Accepted for publication in Astron. Nachr. as
refereed proceedings of Euro3D Science Workshop, IoA Cambridge, May 200
Carbon fluxes in coral reefs. II. Eulerian study of inorganic carbon dynamics and measurement of air-sea CO<sub>2</sub> exchanges
Air-sea CO2 exchanges and the partial pressure of CO2 were measured in surface water overlying 2 coral reefs: Moorea (French Polynesia, austral winter, August 1992), where coral diversity and surface cover are low, and Yonge Reef (Great Barrier Reef, austral summer, December 1993), where coral diversity and cover are comparatively higher. A procedure is proposed to estimate the potential CO2 exchange with the atmosphere by taking into account both the saturation level of oceanic seawater and the equilibration process occurring after water leaves the reef. It is shown that both sites were net sources of CO2 to the atmosphere as a result of the effect of calcification on the dynamics of the inorganic carbon system. The potential global CO2 evasion from the ocean to the atmosphere is about 4 times higher at Yonge Reef than at Moorea. It is also demonstrated that, at both sites, the major exchange of CO2 from sea to air occurs as seawater returns to chemical equilibrium after it has crossed and left the reef. The dynamics of inorganic carbon were studied using the so-called homogeneous buffer factor [beta = dln(pCO(2))/dln(DIC)] (where pCO(2) is the CO2 partial pressure in surface water and DIC is dissolved inorganic carbon), which gave estimates that approximately 80% of the change in inorganic carbon was related to photosynthesis and respiration. This approach showed that the calcification rate was proportional to the net organic production during the day and to the respiration rate at night
IPM in Asia - A review of existing projects in the Philippines and Indonesia
peer reviewedIntegrated Pest Management means a pest management system that, in the context of the associated environment and the population dynamics of the pest species, utilizes ail suitable techniques and methods in as compatible a manner as possible and maintains the pest
populations at levels below those causing economically unacceptable damage or 1055.
FAO-Code- of Conduct 1984
IPM in Asia - A review of existing projects in the Philippines and Indonesia
peer reviewedIntegrated Pest Management means a pest management system that, in the context of the associated environment and the population dynamics of the pest species, utilizes ail suitable techniques and methods in as compatible a manner as possible and maintains the pest
populations at levels below those causing economically unacceptable damage or 1055.
FAO-Code- of Conduct 1984
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