45,218 research outputs found
Probing Mass Segregation in NGC 6397
In this study, we present a detailed study of mass segregation in the
globular clister NGC 6397. First, we carry out a photometric analysis of
projected ESO-VLT data (between 1 and 10 arcmin from the cluster centre),
presenting the luminosity function corrected by completeness. The luminosity
function shows a higher density of bright stars near the central region of the
data, with respect to the outer region. We calculate a deprojected model
(covering the whole cluster) estimating a total number of stars of 193000 +-
19000. The shapes of the surface brightness and density-number profiles versus
the radial coordinate r (instead of the projected coordinate R) lead to a
decreasing luminosity for an average star, and thus of mass, up to 1 arcmin,
quantifying the mass segregation. The deprojected model does not show evidence
of mass segregation outside this region
Gauge fields in a string-cigar braneworld
In this work we investigate the properties of an Abelian gauge vector field
in a thin and in a smoothed string-like braneworld, the so-called string-cigar
model. This thick brane scenario satisfies the regularity conditions and it can
be regarded as an interior and exterior string-like solution. The source
undergoes a geometric Ricci flow which is connected to a variation of the bulk
cosmological constant. The Ricci flow changes the width and amplitude of the
massless mode at the brane core and recover the usual thin string-like behavior
at large distances. By numerical means we obtain the Kaluza-Klein (KK) spectrum
for both the thin brane and the string-cigar. It turns out that both models
exhibit a mass gap between the massless and the massive modes and between the
high and the low mass regimes. The KK modes are smooth near the brane and their
amplitude are enhanced by the string-cigar core. The analogue Schr\"odinger
potential is also tuned by the geometric flow.Comment: The discussion about the Kaluza-Klein spectrum of the gauge field was
improved. Numerical analysis was adapted to the conventional notation on
Kaluza-Klein number. Some graphics were modified for considering other
notation. Results unchanged. References added. Corrected typos. 17 pages. 6
figures. To match version to appears in Physics Letters
Gemini/GMOS photometry of intermediate-age star clusters in the Large Magellanic Cloud
We present Gemini South GMOS g,i photometry of 14 intermediate-age Large
Magellanic Cloud (LMC) star clusters, namely: NGC 2155, 2161, 2162, 2173, 2203,
2209, 2213, 2231, 2249, Hodge 6, SL 244, 505, 674, and 769, as part of a
continuing project to investigate the extended Main Sequence Turnoff (EMSTO)
phenomenon. Extensive artificial star tests were made over the observed field
of view. These tests reveal the observed behaviour of photometric errors with
magnitude and crowding. The cluster stellar density radial profiles were traced
from star counts over the extent of the observed field. We adopt clus- ter
radii and build colour-magnitude diagrams (CMDs) with cluster features clearly
identified. We used the cluster (g,g-i) CMDs to estimate ages from the matching
of theoretical isochrones. The studied LMC clusters are confirmed to be
intermediate-age clusters, which range in age 9.10 < log(t) < 9.60. NGC 2162
and NGC 2249 look like new EMSTO candidates, in addition to NGC 2209, on the
basis of having dual red clumps.Comment: MNRAS, accepte
Influence of public policies on the diffusion of wind and solar PV sources in Brazil and the possible effects of COVID-19
Renewable energy is crucial to achieving carbon neutrality and supporting sustainable development, but its success depends on effective policies. This study aims to evaluate public policies and their influences on the use and diffusion of wind and solar PV into the Brazilian electricity grid and to understand if, and how, the two renewable sources could be affected by the post-COVID-19 pandemic scenario. This work plays an important role in the decarbonization of the electricity sector, highlights the need to modernize the Brazilian industrial park, and addresses new barriers to the development of renewable sources in the country. To carry out the analysis and answer the research questions, a mixed methodological approach was adopted covering the quantitative and qualitative aspects, led by a rigorous systematic review of the literature and semi-structured interviews with Brazilian stakeholders. The results revealed that 1/4 of the policies, characterized by socio-economic drives, were responsible for the growth of the share of wind and solar PV supply in the electrical mix, contributing to the decarbonization of the Brazilian energy mix. The results also suggest that new policies will be needed to ensure a greater presence of both sources in the electricity mix. The findings of the study reveal unpublished and valuable information capable of supporting policymakers and stakeholders in the diffusion of renewable sources. Further studies are needed to highlight other aspects, such as the need to modernize the âdistributionâ network and storage system for renewable technologies
Photo-ionization of planetary winds: case study HD209458b
Close-in hot Jupiters are exposed to a tremendous photon flux that ionizes
the neutral escaping material from the planet leaving an observable imprint
that makes them an interesting laboratory for testing theoretical models. In
this work we present 3D hydrodynamic simulations with radiation transfer
calculations of a close-in exoplanet in a blow-off state. We calculate the
Ly- absorption and compare it with observations of HD 209458b an
previous simplified model results.Our results show that the hydrodynamic
interaction together with a proper calculation of the photoionization proccess
are able to reproduce the main features of the observed Ly- absorption,
in particular at the blue-shifted wings of the line. We found that the ionizing
stellar flux produce an almost linear effect on the amount of absorption in the
wake. Varying the planetary mass loss rate and the radiation flux, we were able
to reproduce the absorption observed at .Comment: 9 pages, 6 figure
On the definition of Quantum Free Particle on Curved Manifolds
A selfconsistent definition of quantum free particle on a generic curved
manifold emerges naturally by restricting the dynamics to submanifolds of
co-dimension one.
PACS 0365 0240Comment: 8 p., phyzzx macropackag
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