10,092 research outputs found
Integral field observations of the blue compact galaxy Haro14. Star formation and feedback in dwarf galaxies
(Abridged) Low-luminosity, gas-rich blue compact galaxies (BCG) are ideal
laboratories to investigate many aspects of the star formation in galaxies. We
study the morphology, stellar content, kinematics, and the nebular excitation
and ionization mechanism in the BCG Haro 14 by means of integral field
observations with VIMOS in the VLT. From these data we build maps in continuum
and in the brighter emission lines, produce line-ratio maps, and obtain the
velocity and velocity dispersion fields. We also generate the integrated
spectrum of the major HII regions and young stellar clusters identified in the
maps to determine reliable physical parameters and oxygen abundances. We find
as follows: i) the current star formation in Haro 14 is spatially extended with
the major HII regions placed along a linear structure, elongated in the
north-south direction, and in a horseshoe-like curvilinear feature that extends
about 760 pc eastward; the continuum emission is more concentrated and peaks
close to the galaxy center; ii) two different episodes of star formation are
present: the recent starburst, with ages 6 Myrs and the intermediate-age
clusters, with ages between 10 and 30 Myrs; these stellar components rest on a
several Gyr old underlying host galaxy; iii) the H/H pattern is
inhomogeneous, with excess color values varying from E(B-V)=0.04 up to
E(B-V)=1.09; iv) shocks play a significant role in the galaxy; and v) the
velocity field displays a complicated pattern with regions of material moving
toward us in the east and north galaxy areas. The morphology of Haro 14, its
irregular velocity field, and the presence of shocks speak in favor of a
scenario of triggered star formation. Ages of the knots are consistent with the
ongoing burst being triggered by the collective action of stellar winds and
supernovae originated in the central clusters.Comment: 18 pages, 17 figures. Accepted for publication in A&
Probing star formation and feedback in dwarf galaxies. Integral field view of the blue compact galaxy Tololo 1937-423
(Abridged) Blue compact galaxies (BCG) are gas-rich, low-mass, small systems
that form stars at unusually high rates. This makes them excellent laboratories
for investigating the process of star-formation (SF) at galactic scales and the
effects of massive stellar feedback on the interstellar (and intergalactic)
medium.
We analyzed the BCG Tololo 1937-423 using optical integral field spectroscopy
with VIMOS at the Very Large Telescope to probe its morphology, stellar
content, nebular excitation and ionization properties, and the kinematics of
its warm ionized gas.
We found that Tololo 1937-423 is currently undergoing an extended starburst,
with nine major clumps. The galaxy presents a single continuum peak
that is not cospatial with any knot in emission lines, indicating at least two
relatively recent episodes of SF. The inhomogeneous dust distribution reaches
its maximum roughly at the position of the continuum peak. We found shocked
regions in the galaxy outer regions and at the edges of the SF knots. The
oxygen abundance is similar in all the SF regions, suggesting a chemically
homogeneous ionized interstellar medium over spatial scales of several kpc. The
ionized gas kinematics displays an overall regular rotation around a
northwest-southeast axis.
The morphology of the galaxy and the two different episodes of SF suggest a
scenario of triggered (induced by supernova shock waves) SF acting in Tololo
1937-423. The inferred ages for the different SF episodes (~13-80 Myr for the
central post-starburst and 5-7 Myr for the ongoing SF) are consistent with
triggered SF, with the most recent SF episode caused by the collective effect
of stellar winds and supernova explosions from the central post-starburst. The
velocity dispersion pattern, with higher velocity dispersions found at the
edges of the SF regions, and shocked regions in the galaxy, also favor this
scenario.Comment: 16 pages, 18 figures. Accepted for publication in A&
Spider diversity (Arachnida: Araneae) in Atlantic Forest areas at Pedra Branca State Park, Rio de Janeiro, Brazil
BACKGROUND: There has never been any published work about the diversity of spiders in the city of Rio de Janeiro using analytical tools to measure diversity. The only available records for spider communities in nearby areas indicate 308 species in the National Park of Tijuca and 159 species in Marapendi Municipal Park. These numbers are based on a rapid survey and on an one-year survey respectively. NEW INFORMATION: This study provides a more thorough understanding of how the spider species are distributed at Pedra Branca State Park. We report a total of 14,626 spider specimens recorded from this park, representing 49 families and 373 species or morphospecies, including at least 73 undescribed species. Also, the distribution range of 45 species was expanded, and species accumulation curves estimate that there is a minimum of 388 (Bootstrap) and a maximum of 468 species (Jackknife2) for the sampled areas. These estimates indicates that the spider diversity may be higher than observed.Fil: Castanheira, Pedro. Universidade Federal do Rio de Janeiro; BrasilFil: Pérez González, Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Baptista, Renner L. C.. Universidade Federal do Rio de Janeiro; Brasi
Selection of AGN candidates in the GOODS-South Field through SPITZER/MIPS 24 m variability
We present a study of galaxies showing mid-infrared variability in data taken
in the deepest Spitzer/MIPS 24 m surveys in the GOODS-South field. We
divide the dataset in epochs and subepochs to study the long-term
(months-years) and the short-term (days) variability. We use a
-statistics method to select AGN candidates with a probability
1% that the observed variability is due to statistical errors alone. We find 39
(1.7% of the parent sample) sources that show long-term variability and 55
(2.2% of the parent sample) showing short-term variability. That is, 0.03
sources arcmin for both, long-term and short-term variable
sources. After removing the expected number of false positives inherent to the
method, the estimated percentages are 1.0% and 1.4% of the parent sample for
the long-term and short-term respectively. We compare our candidates with AGN
selected in the X-ray and radio bands, and AGN candidates selected by their IR
emission. Approximately, 50% of the MIPS 24 m variable sources would be
identified as AGN with these other methods. Therefore, MIPS 24 m
variability is a new method to identify AGN candidates, possibly dust obscured
and low luminosity AGN, that might be missed by other methods. However, the
contribution of the MIPS 24 m variable identified AGN to the general AGN
population is small ( 13%) in GOODS-South.Comment: Accepted for publication in MNRA
Desarrollo y validación de la escala de relajación-mindfulness para adolescentes (EREMIND-A)
Indexación: Scopus.Background: The aim of this investigation was to validate the Relaxation- Mindfulness Scale for Adolescents (EREMIND-A), consisting of 18 items and three factors (Attention-Concentration in the present moment; Relaxation (abilities and attitudes); and Sensory awareness/Contemplation/ Interiority). Method: The validation was done with a sample of Secondary Education and Baccalaureate students from four different centres in Spain (n = 1.120). EFA and CFA of the EREMIND-A were performed and construct and incremental validities calculated. Results: Initial results confi rm the validity and reliability of the scale. Conclusions: There is a need for a broader conceptualization of mindfulness, as well as the inclusion and analysis of other related and cross-cutting concepts. The research in this sense will propitiate the adaptation of the Mindfulness- Based Interventions to the reality of the adolescents in the educational centers, where relaxation and the interiority are aspects to be taken into consideration. © 2018 Psicothema.Antecedentes: el objetivo de esta investigación fue validar la Escala de relajación-Mindfulness para Adolescentes (EREMIND-A), que contiene 18 ítems y tres factores (Atención-Concentración en el momento presente; Relajación (habilidades y actitudes); Consciencia Sensorial/Contemplación/Interioridad. Método: la validación se realizó con una muestra de estudiantes de Educación Secundaria y Bachillerato de cuatro centros diferentes en España (n = 1.120). Se realizaron análisis factoriales exploratorios y confirmatorios de la escala y se calcularon la validez de constructo e incremental. Resultados: los resultados iniciales confirman la fiabilidad y validez de la escala. Conclusiones: es necesaria una conceptualización más amplia de la atención plena, así como la inclusión y análisis de otros conceptos relacionados y transversales. La investigación en este sentido propiciará la adaptación de las intervenciones basadas en mindfulness a la realidad de los adolescentes en los centros educativos, donde la relajación y la interioridad son aspectos a tener en consideración.http://www.psicothema.com/pdf/4475.pd
Un currículo para el estudio de la historia de la ciencia en Secundaria : la experiencia del Seminario Orotava de Historia de la Ciencia
The curricula of two disciplines on History of Science at the High School level have been elaborated as part of the activities of a singular experience, Seminario Orotava de Historia de la Ciencia. The philosophy of the design considers science as an essential part of culture and interdisciplinarity as the most fitted method of teaching and learnign in a significative way
Vector magnetic hysteresis of hard superconductors
Critical state problems which incorporate more than one component for the
magnetization vector of hard superconductors are investigated. The theory is
based on the minimization of a cost functional
which weighs the changes of the magnetic field vector within the sample. We
show that Bean's simplest prescription of choosing the correct sign for the
critical current density in one dimensional problems is just a particular
case of finding the components of the vector . is
determined by minimizing under the constraint , with a bounded set. Upon the selection of
different sets we discuss existing crossed field measurements and
predict new observable features. It is shown that a complex behavior in the
magnetization curves may be controlled by a single external parameter, i.e.:
the maximum value of the applied magnetic field .Comment: 10 pages, 9 figures, accepted in Phys. Rev.
Paleopathological study of skeletal remains of Ursids of the Pleistocene-Holocene of the Iberian Península
An exhaustive paleontologic study of skeletal remains of Ursids of the Pleistocene-Holocene from the lberian Peninsula was realized by one of us (Torres, 1984). Many of the pieces studied here were selected by this author. Other pieces proceed from recent excavations in the exceptional site of Ibeas, from the Sierra de Atapuerca, Burgos, Spain, of the Middle Pleistocene, which is providing human remains
Understanding star formation and feedback in small galaxies. The case of the blue compact dwarf Mrk 900
(Abridged) Low-luminosity, active star-forming blue compact galaxies (BCGs)
are excellent laboratories for investigating the process of star formation on
galactic scales and probing the interplay between massive stars and the
surrounding interstellar (or intergalactic) medium. We investigated the
morphology, structure, and stellar content of the Blue Compact Galaxy Mrk 900,
combining optical integral field observations obtained with VIMOS at the VLT
and deep broad-band photometry taken at the 2.5 m NOT telescope. From the
integral field data, we built continuum, emission, and diagnostic line ratio
maps and produced velocity and velocity dispersion maps. We also generated the
integrated spectrum of the major HII regions and the nuclear area to determine
reliable physical parameters and oxygen abundances. The broad-band data,
tracing the galaxy up to radius 4 kpc, allowed us to investigate the properties
of the low surface brightness underlying stellar host. We disentangle two
different stellar components in Mrk 900: a young population, which resolves
into individual stellar clusters with ages ~5.5-6.6 Myr and extends about 1 kpc
along the galaxy minor axis, is placed on top of a rather red and regular
shaped underlying stellar host, several Gyr old. We find evidence of a
substantial amount of dust and an inhomogeneous extinction pattern, with a dust
lane crossing the central starburst. Mrk 900 displays overall rotation,
although distorted in the central, starburst regions; the dispersion velocity
map is highly inhomogeneous, with values increasing up to 60 kms at the
periphery of the SF regions, where we also find hints of the presence of
shocks. Our observational results point to an interaction or merger with a
low-mass object or infalling gas as plausible trigger mechanisms for the
present starburst event.Comment: 17 pages, 19 figures. Accepted for publication in A&
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