Abstract
We report on a chemo-dynamical analysis of SPLUS J142445.34−254247.1 (SPLUS J1424−2542), an extremely metal-poor halo star enhanced in elements formed by the rapid neutron-capture process (
...r
-process). This star was first selected as a metal-poor candidate from its narrowband S-PLUS photometry and followed up spectroscopically in medium resolution with Gemini-South/GMOS, which confirmed its low-metallicity status. High-resolution spectroscopy was gathered with GHOST at Gemini-South, allowing for the determination of the chemical abundances for 36 elements, from carbon to thorium. At Fe/H = −3.39, SPLUS J1424−2542 is one of the lowest-metallicity stars with measured Th and has the highest
log
ϵ
(
Th
/
Eu
)
observed to date, making it part of the “actinide-boost” category of
r
-process–enhanced stars. The analysis presented here suggests that the gas cloud from which SPLUS J1424−2542 formed must have been enriched by at least two progenitor populations. The light-element (
Z
≤ 30) abundance pattern is consistent with the yields from a supernova explosion of metal-free stars with 11.3–13.4
M
⊙
, and the heavy-element (
Z
≥ 38) abundance pattern can be reproduced by the yields from a neutron star merger (1.66
M
⊙
and 1.27
M
⊙
) event. A kinematical analysis also reveals that SPLUS J1424−2542 is a low-mass, old halo star with a likely in situ origin, not associated with any known early merger events in the Milky Way.
Objetivos: Describir las características socio-epidemiológicas de los casos de Tuberculosis (TBC) Pediátrica, y aspectos asociados a su incidencia, del 2005 al 2018, en Servicios de Salud ...Metropolitano Norte, Central y Sur de Chile.Pacientes y Método: Estudio descriptivo con componente ecológico de tipo serie temporal. Se estudió la incidencia de TBC anuales globales y según edad, sexo, localización de la TBC, confirmación bacteriológica, co-infección con virus de inmunodeficiencia humana (VIH), país de procedencia y efectividad de la terapia anti-tuberculosis. Se realizó un análisis de correlación entre la tasa de incidencia y la proporción de casos extranjeros.Resultados: Entre el 2005 y 2018 se notificaron 160 casos de TBC en menores de 15 años. Mediana de edad de 8 años, 55% de sexo masculino. La TBC Pulmonar afectó a 56,2%, donde hubo confirmación bacteriológica en un 65,6%. La tasa de incidencia aumentó de 0,5 a 4,9 casos x 100.000 habitantes, de 2010 a 2018. Ese último año, concentra un 20,6% de los casos ocurridos en 14 años de observación. La proporción de casos en menores extranjeros es inferior a los casos de niños(as) chilenos. Además, se observó un 91,3% de éxito en el tratamiento, un 6,5% de casos trasladados de Servicio y 2 fallecidosConclusión: Los resultados de este estudio dan cuenta de una grave reemergencia epidemiológica de TBC. Se recomienda que las políticas de control y eliminación consideren estrategias focalizadas en pacientes pediátricos, orientándose a pesquisar activamente los casos nuevos y hacer más eficiente el estudio de contacto.
The Gemini multiconjugate adaptive optics system - GeMS, a facility instrument mounted on the Gemini South telescope, delivers a uniform, near diffraction limited images at near-infrared wavelengths ...(0.95-2.5 μm) over a field of view of 120 arcsec. GeMS is the first sodium layer based multilaser guide star adaptive optics system used in astronomy. It uses five laser guide stars distributed on a 60 arcsec square constellation to measure for atmospheric distortions and two deformable mirrors to compensate for it. In this paper, the second one devoted to describe the GeMS project, we present the commissioning, overall performance and operational scheme of GeMS. Performance of each subsystem is derived from the commissioning results. The typical image quality, expressed in full with at half-maximum, Strehl ratios and variations over the field delivered by the system are then described. A discussion of the main contributor to performance limitation is carried out. Finally, overheads and future system upgrades are described.
ABSTRACT
Pristine_183.6849 + 04.8619 (P1836849) is an extremely metal-poor (Fe/H = −3.3 ± 0.1) star on a prograde orbit confined to the Galactic disc. Such stars are rare and may have their origins ...in protogalactic fragments that formed the early Milky Way, in low-mass satellites accreted later, or forming in situ in the Galactic plane. Here, we present a chemo-dynamical analysis of the spectral features between 3700−11 000 Å from a high-resolution spectrum taken during Science Verification of the new Gemini High-resolution Optical SpecTrograph. Spectral features for many chemical elements are analysed (Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Fe, Ni), and valuable upper limits are determined for others (C, Na, Sr, Ba). This main sequence star exhibits several rare chemical signatures, including (i) extremely low metallicity for a star in the Galactic disc, (ii) very low abundances of the light α-elements (Na, Mg, Si) compared to other metal-poor stars, and (iii) unusually large abundances of Cr and Mn, where Cr, Mn/FeNLTE > +0.5. A comparison to theoretical yields from supernova models suggests that two low-mass Population III objects (one 10 M⊙ supernova and one 17 M⊙ hypernova) can reproduce the abundance pattern well (reduced χ2 < 1). When this star is compared to other extremely metal-poor stars on quasi-circular, prograde planar orbits, differences in both chemistry and kinematics imply there is little evidence for a common origin. The unique chemistry of P1836849 is discussed in terms of the earliest stages in the formation of the Milky Way.
Abstract
The Gemini High-resolution Optical SpecTrograph (GHOST) is the newest high-resolution spectrograph to be developed for a large-aperture telescope, recently deployed and commissioned at the ...Gemini-South telescope. In this paper, we present the first science results from the GHOST spectrograph taking during its commissioning runs. We have observed the bright metal-poor benchmark star HD 122563, along with two stars in the ultrafaint dwarf galaxy Reticulum II (Ret
ii
), one of which was previously identified as a candidate member, but did not have a previous detailed chemical abundance analysis. We find that this candidate (GDR3 0928) to be a bona fide member of Ret
ii
, and from a spectral synthesis analysis it is also revealed to be a CEMP-
r
star, with significant enhancements in several light elements (C, N, O, Na, Mg, and Si), in addition to featuring an
r
-process enhancement like many other Ret
ii
stars. The light-element enhancements in this star resemble the abundance patterns seen in the CEMP-no stars of other ultrafaint dwarf galaxies, and are thought to have been produced by an independent source from the
r
-process. These unusual abundance patterns are thought to be produced by faint supernovae, which may be produced by some of the earliest generations of stars.
Resumen: Objetivos: Describir las características socio-epidemiológicas de los casos de Tuberculosis (TBC) Pediátrica, y aspectos asociados a su incidencia, del 2005 al 2018, en Servicios de Salud ...Metropolitano Norte, Central y Sur de Chile. Pacientes y Método: Estudio descriptivo con componente ecológico de tipo serie temporal. Se estudió la incidencia de TBC anuales globales y según edad, sexo, localización de la TBC, confirmación bacteriológica, co-infección con virus de inmunodeficiencia humana (VIH), país de procedencia y efectividad de la terapia anti-tuberculosis. Se realizó un análisis de correlación entre la tasa de incidencia y la proporción de casos extranjeros. Resultados: Entre el 2005 y 2018 se notificaron 160 casos de TBC en menores de 15 años. Mediana de edad de 8 años, 55% de sexo mas culino. La TBC Pulmonar afectó a 56,2%, donde hubo confirmación bacteriológica en un 65,6%. La tasa de incidencia aumentó de 0,5 a 4,9 casos x 100.000 habitantes, de 2010 a 2018. Ese último año, concentra un 20,6% de los casos ocurridos en 14 años de observación. La proporción de casos en menores extranjeros es inferior a los casos de niños(as) chilenos. Además, se observó un 91,3% de éxito en el tratamiento, un 6,5% de casos trasladados de Servicio y 2 fallecidos Conclusión: Los resul tados de este estudio dan cuenta de una grave reemergencia epidemiológica de TBC. Se recomienda que las políticas de control y eliminación consideren estrategias focalizadas en pacientes pediátricos, orientándose a pesquisar activamente los casos nuevos y hacer más eficiente el estudio de contacto.
Depending on the final application, several methodologies for traffic emission estimation have been developed. Emission estimation based on total miles traveled or other average factors is a ...sufficient approach only for extended areas such as national or worldwide areas. For road emission control and strategies design, microscale analysis based on real-world emission estimations is often required. This involves actual driving behavior and emission factors of the local vehicle fleet under study.
This paper reports on a microscale model for hot road emissions and its application to the metropolitan region of the city of Santiago, Chile. The methodology considers the street-by-street hot emission estimation with its temporal and spatial distribution. The input data come from experimental emission factors based on local driving patterns and traffic surveys of traffic flows for different vehicle categories. The methodology developed is able to estimate hourly hot road CO, total unburned hydrocarbons (THCs), particulate matter (PM), and NO
x
emissions for predefined day types and vehicle categories.
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