1,049 research outputs found
Extragalactic planetary nebulae as mass tracers: biases in the estimate of dynamical quantities
Planetary Nebulae (PNe) are very important kinematical tracers of the outer
regions of early-type galaxies, where the integrated light techniques fail.
Under ad hoc assumptions, they allow measurements of rotation velocity and
velocity dispersion profile from descrete radial velocity fields. We present
the results on the precision allowed by different set of radial velocity
samples, discuss the hypotheses in the analysis of descrete velocity fields and
their impact on the inferred kinematics of the stellar population.Comment: 4 pages, 2 figures. To appear on ``Galaxy Dynamics: from Early
Universe to the Present'', ASP Conf. Ser., F. Combes, G.A. Mamon and V.
Charmandaris (eds.
On the shape of the light profiles of early-type galaxies
We have obtained the best fit to the light profiles of a luminosity limited
sample of elliptical and S0 galaxies with a power law \rn, letting the exponent
remain free rather than keeping it fixed at as in the well known \GV
formula. The introduction of a free parameter in the fitting formula (ranging
from for kpc to for kpc) is justified by
the existence of a good correlation between and the global galaxian
parameters, such as total luminosity and scale-radius. This result seems to be
in line with the segregation of properties between the `ordinary' and `bright'
families of early-type galaxies, and has consequence for the claimed
independence of the shape of galaxy profiles with respect to the Fundamental
Plane parameters.Comment: 10 pages, postscript file including figures, PADOVA (archived file
truncated during email transfer
What can we learn by squeezing a liquid
Relaxation times for different temperatures, T, and specific volumes, V,
collapse to a master curve versus TV^g, with g a material constant. The
isochoric fragility, m_V, is also a material constant, inversely correlated
with g. From these we obtain a 3-parameter function, which fits accurately
relaxation times of several glass-formers over the supercooled regime, without
any divergence below Tg. Although the 3 parameters depend on the material, only
g significant varies; thus, by normalizing material-specific quantities related
to g, a universal power law for the dynamics is obtained.Comment: 12 pages, 4 figure
Surface Brightness Fluctuations: a theoretical point of view
We present new theoretical evaluations of optical and near-IR Surface
Brightness Fluctuations (SBF) magnitudes for single-burst stellar populations
in the age range t=5-15 Gyr and metallicity from Z_{\sun}/200 to 2Z_{\sun}.
Our theoretical predictions can be successfully used to derive reliable
distance evaluations. They also appear to be a new and valuable tool to trace
the properties of unresolved stellar populations.Comment: 2 pages, incl. 1 figure, uses newpasp.sty, to be published in ``New
Horizons in Globular Cluster Astronomy'', ASP Conference Series, 2002; Eds.:
G. Piotto, G. Meylan, G. Djorgowski and M. Riello, in pres
The Luminosity and Mass Function of the Globular Cluster NGC1261
I-band CCD images of two large regions of the Galactic globular cluster NGC
1261 have been used to construct stellar luminosity functions (LF) for 14000
stars in three annuli from 1.4' from the cluster center to the tidal radius.
The LFs extend to M_I~8 and tend to steepen from the inner to the outer
annulus, in agreement with the predictions of the multimass King-Michie model
that we have calculated for this cluster. The LFs have been transformed into
mass functions. Once corrected for mass segregation the global mass function of
NGC 1261 has a slope x_0=0.8+/-0.5Comment: 9 pages, A&A macros, accepted for publication in A&
Structure and kinematics of the peculiar galaxy NGC 128
This is a multiband photometric and spectroscopic study of the peculiar S0
galaxy NGC128. We present results from broad (B and R) and narrow band optical
CCD photometry, near (NIR) and far (FIR) infrared observations, long slit
spectroscopy, and Fabry-Perot interferometry (CIGALE). The peculiar peanut
shape morphology of the galaxy is observed both at optical and near-infrared
wavelengths. The stellar disk is thick and distorted (arc-bended), with a color
asymmetry along the major axis due to the presence of a large amount of dust,
estimated through NIR and FIR data of ~6x10^6 M_sun, in the region of
interaction with the companion galaxy NGC127. The color maps are nearly uniform
over the whole galaxy, but for the major axis asymmetry, and a small gradient
toward the center indicating the presence of a redder disk-like component. The
H_alpha image indeed reveals the existence of a tilted gaseous ``disk'' around
the center, oriented with the major axis toward the companion galaxy NGC127.
Long slit and CIGALE data confirm the presence of gas in a disk-like component
counter-rotating and inclined approximately of 50 deg. to the line of sight.
The mass of the gas disk in the inner region is ~2.7x10^4 M_sun. The stellar
velocity field is cylindrical up to the last measured points of the derived
rotation curves, while the velocity dispersion profiles are typical for an S0
galaxy, but for an extended constant behaviour along the minor axis.Comment: accepted for pubblication in A&A Supp
Simulating CCD images of elliptical galaxies
We introduce a procedure developed by the ``Teramo Stellar Populations
Tools'' group (Teramo-SPoT), specifically optimized to obtain realistic
simulations of CCD images of elliptical galaxies.
Particular attention is devoted to include the Surface Brightness Fluctuation
(SBF) signal observed in ellipticals and to simulate the Globular Cluster (GC)
system in the galaxy, and the distribution of background galaxies present in
real CCD frames. In addition to the physical properties of the simulated
objects - galaxy distance and brightness profile, luminosity function of GC and
background galaxies, etc. - the tool presented allows the user to set some of
the main instrumental properties - FoV, zero point magnitude, exposure time,
etc.Comment: Presented at From Stars to Galaxies: Building the Pieces to Build up
the Universe (StarGal 2006), Venice, Italy, 16-20 Oct 200
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