1,379 research outputs found
SuperMALT: Physical and Chemical Properties of Massive and Dense Clumps
The SuperMALT survey is observing 76 MALT90 clumps at different evolutionary
stages (from pre-stellar or quiescent to HII) in high excitation molecular
lines and key isotopomers using the Apex 12m telescope with an angular
resolution of 20" and a velocity resolution of 0.1 km/s. The aim of
this survey is to determine the physical, chemical, and kinematical properties
of the gas within clumps as they evolve. Here we report some preliminary
results based on observations of the =3-2 \& 4-3 lines of HNC, HCN, HCO,
NH and of the =3-2 line of the isotopologue HCO. We find
that the morphologies and line profiles vary with the evolutionary stage of the
clumps. The average line width increases from quiescent to HII clumps while
line ratios show hint of chemical differences among the various evolutionary
stages.Comment: 7 pages, 6 figures, Astrochemistry VII: IAU Symposium No. 33
A parsec-scale flow associated with the IRAS 16547-4247 radio jet
IRAS 16547-4247 is the most luminous (6.2 x 10^4 Lsun) embedded young stellar
object known to harbor a thermal radio jet. We report the discovery using
VLT-ISAAC of a chain of H_2 2.12 um emission knots that trace a collimated flow
extending over 1.5 pc. The alignment of the H_2 flow and the central location
of the radio jet implies that these phenomena are intimately linked. We have
also detected using TIMMI2 an isolated, unresolved 12 um infrared source
towards the radio jet . Our findings affirm that IRAS 16547-4247 is excited by
a single O-type star that is driving a collimated jet. We argue that the
accretion mechanism which produces jets in low-mass star formation also
operates in the higher mass regime.Comment: Accepted for publication in ApJL, 10 pages, 2 figure
APEX Millimeter Observations of Methanol Emission Toward High-Mass Star-Forming Cores
We present 247-GHz molecular line observations of methanol (CHOH) toward
sixteen massive star-forming regions, using the APEX telescope with an angular
resolution of . The sample covers a range of evolutionary states,
including warm molecular cores, hot molecular cores, and ultracompact HII
regions. The hot cores, all of which include UC HII regions, show rich
molecular line spectra, although the strength of different species and
transitions varies from source to source. In contrast, the warm cores do not
show significant molecular line emission. Multiple methanol transitions are
detected toward nine of the hot cores; eight of these had enough transitions to
use the rotation diagram method to estimate rotational temperatures and column
densities. The temperatures lie in the range 104168 K and column densities
from to cm. Using the average methanol
line parameters, we estimate virial masses, which fall in the range from 145 to
720 M and proved to be significantly higher than the measured gas
masses. We discuss possible scenarios to explain the chemical differences
between hot cores and warm molecular cores. One of the observed methanol lines,
at 247.228 GHz, is predicted to show class II maser
emission, similar in intensity to previously reported masers at
157 GHz. We did not find any clear evidence for maser emission among the
observed sources; however, a weak maser in this line may exist in G345.01+1.79.Comment: Accepted for publication in The Astronomical Journa
Physical characteristics of G331.5-0.1: The luminous central region of a Giant Molecular Cloud
We report molecular line and dust continuum observations toward the high-mass
star forming region G331.5-0.1, one of the most luminous regions of massive
star-formation in the Milky Way, located at the tangent region of the Norma
spiral arm, at a distance of 7.5 kpc. Molecular emission was mapped toward the
G331.5-0.1 GMC in the CO (J=1-0) and C18O (J=1-0) lines with NANTEN, while its
central region was mapped in CS (J=2-1 and J=5-4) with SEST, and in CS (J=7-6)
and 13CO (J=3-2) with ASTE. Continuum emission mapped at 1.2 mm with SIMBA and
at 0.87 mm with LABOCA reveal the presence of six compact and luminous dust
clumps, making this source one of the most densely populated central regions of
a GMC in the Galaxy. The dust clumps are associated with molecular gas and they
have the following average properties: size of 1.6 pc, mass of 3.2x10^3 Msun,
molecular hydrogen density of 3.7x10^4 cm^{-3}, dust temperature of 32 K, and
integrated luminosity of 5.7x10^5 Lsun, consistent with values found toward
other massive star forming dust clumps. The CS and 13CO spectra show the
presence of two velocity components: a high-velocity component at ~ -89 km
s^{-1}, seen toward four of the clumps, and a low-velocity component at ~ -101
km s^{-1} seen toward the other two clumps. Radio continuum emission is present
toward four of the molecular clumps, with spectral index estimated for two of
them of 0.8+-0.2 and 1.2+-0.2. A high-velocity molecular outflow is found at
the center of the brightest clump, with a line width of 26 km s^{-1} (FWHM) in
CS (J=7-6). Observations of SiO (J=7-6 and J=8-7), and SO (J_K=8_8-7_7 and
J_K=8_7-7_6) lines provide estimates of the gas rotational temperature toward
this outflow >120 K and >75 K, respectively.Comment: 34 pages, 20 figures, 11 tables, Accepted for Publication in The
Astrophysical Journa
Assessing molecular outflows and turbulence in the protostellar cluster Serpens South
Molecular outflows driven by protostellar cluster members likely impact their
surroundings and contribute to turbulence, affecting subsequent star formation.
The very young Serpens South cluster consists of a particularly high density
and fraction of protostars, yielding a relevant case study for protostellar
outflows and their impact on the cluster environment. We combined CO
observations of this region using the Combined Array for Research in
Millimeter-wave Astronomy (CARMA) and the Institut de Radioastronomie
Millim\'{e}trique (IRAM) 30 m single dish telescope. The combined map allows us
to probe CO outflows within the central, most active region at size scales of
0.01 pc to 0.8 pc. We account for effects of line opacity and excitation
temperature variations by incorporating CO and CO data for the
and transitions (using Atacama Pathfinder Experiment and
Caltech Submillimeter Observatory observations for the higher CO transitions),
and we calculate mass, momentum, and energy of the molecular outflows in this
region. The outflow mass loss rate, force, and luminosity, compared with
diagnostics of turbulence and gravity, suggest that outflows drive a sufficient
amount of energy to sustain turbulence, but not enough energy to substantially
counter the gravitational potential energy and disrupt the clump. Further, we
compare Serpens South with the slightly more evolved cluster NGC 1333, and we
propose an empirical scenario for outflow-cluster interaction at different
evolutionary stages.Comment: 26 pages, 15 figures, accepted for publication in the Astrophysical
Journa
G345.45+1.50: An expanding ring-like structure with massive star formation
Ring-like structures in the ISM are commonly associated with high-mass stars.
Kinematic studies of large structures in GMCs toward these ring-like structures
may help us to understand how massive stars form. The origin and properties of
the ring-like structure G345.45+1.50 is investigated through observations of
the 13CO(3-2) line. The aim of the observations is to determine the kinematics
in the region and to compare physical characteristics estimated from gas
emission with those previously determined using dust continuum emission. The
13CO(3-2) line was mapped toward the whole ring using the APEX telescope. The
ring is found to be expanding with a velocity of 1.0 km/s, containing a total
mass of 6.9e3 Msun, which agrees well with that determined using 1.2 mm dust
continuum emission. An expansion timescale of 3e6 yr and a total energy of 7e46
erg are estimated. The origin of the ring might have been a supernova
explosion, since a 35.5 cm source, J165920-400424, is located at the center of
the ring without an infrared counterpart. The ring is fragmented, and 104
clumps were identified with diameters of between 0.3 and 1.6 pc, masses of
between 2.3 and 7.5e2 Msun, and densities of between 1.0e2 and 1.0e4 cm^-3. At
least 18% of the clumps are forming stars, as is shown in infrared images.
Assuming that the clumps can be modeled as Bonnor-Ebert spheres, 13 clumps are
collapsing, and the rest of them are in hydrostatic equilibrium with an
external pressure with a median value of 4e4 K cm^-3. In the region, the
molecular outflow IRAS 16562-3959 is identified, with a velocity range of 38.4
km/s, total mass of 13 Msun, and kinematic energy of 7e45 erg. Finally, five
filamentary structures were found at the edge of the ring with an average size
of 3 pc, a width of 0.6 pc, a mass of 2e2 Msun, and a column density of 6e21
cm^-2
Gregory Bateson: un pensamiento (complejo) para pensar la complejidad. Un intento de lectura/escritura terapéutica
El artículo nos ofrece una mirada al hombre y a su vasto espectro del pensamiento, asumiendo la dificultad de intentar ‘atrapar’ el núcleo duro del proyecto bensoniano. Bateson es un personaje que transrecorrió disciplinas -comunicación, etnología y antropología, psiquiatría/psicología, genética, filosofía, biología, zoología, etología y etiología, cibernética- instalándose en lo que él llama la historia natural de las ideas o ecología de la mente. El presente artículo expone un apronte a este vasto pensamiento Batesoniano, y en particular su epistemología para el cambio cultural.L’article nous offre un regard sur l’homme et sur l’amplitude de sa pensée, assumant toute la difficulté qui consiste à tenter de “capter” le noyau dure du projet bensonien. Bateson est un personnage qui a traversé les disciplines – communication, ethnologie et anthropologie, psychiatrie/psychologie, génétique, philosophie, biologie, zoologie, éthologie et étiologie, cybernétique – en se plaçant dans ce que lui-même nomme l’histoire naturelle des idées ou écologie de l’esprit. Cet article expose une approche de cette vaste pensée Batesonienne et plus particulièrement son épistémologie pour le changement culturel.The article offers a glance at man and his vast range of thought, assuming the difficulty of trying to 'catch' the core of the project bensoniano. Bateson is a character that transtravelled disciplines -communication, ethnology and anthropology, psychiatry/psychology, genetics, philosophy, biology, zoology, ethology and etiology, cybernetics- settling in what he calls the natural history of ideas, or ecology of the mind. This paper presents a approach to this vast Batesonian thought, and particularly his epistemology for cultural change
Teletrabajo y carga laboral de los servidores públicos en un gobierno autónomo descentralizado en Ecuador, 2022
El presente estudio de investigación tuvo como objetivo determinar la relación
entre el teletrabajo y carga laboral de los servidores públicos en un Gobierno
Autónomo Descentralizado en Ecuador, 2022; siendo una investigación por su
finalidad básica, correlacional de naturaleza cuantitativa con diseño no
experimental, en una muestra no probabilística de 51 servidores públicos,
utilizando la técnica para recopilar información como la encuesta basado en dos
cuestionarios para ambas variables de estudio. En los resultados se halló
relación significativa entre teletrabajo y carga laboral de los servidores públicos
en un Gobierno Autónomo Descentralizado en Ecuador, 2022; cuyo coeficiente
de correlación de R de Pearson fue ,715** (p=,012 <0.05). Asimismo, también
se halló relación significativa entre el teletrabajo y las dimensiones de carga
laboral; horas laboradas R de Pearson= ,654** (p=0.005 <0.01); producto
entregado R de Pearson= ,799** (p=0.004 <0.01), cansancio físico R de
Pearson= ,433** (p=,000) y cansancio mental R de Pearson= ,596** (p=,000) de
los servidores públicos en un Gobierno Autónomo Descentralizado en Ecuador,
202
High Angular Resolution Observations of the Collimated Jet Source Associated with a Massive Protostar in IRAS 16547-4247
A triple radio source recently detected in association with the luminous
infrared source IRAS 16547-4247 has been studied with high angular resolution
and high sensitivity with the Very Large Array at 3.6 and 2 cm. Our
observations confirm the interpretation that the central object is a thermal
radio jet, while the two outer lobes are most probably heavily obscured HH
objects. The thermal radio jet is resolved angularly for the first time and
found to align closely with the outer lobes. The opening angle of the thermal
jet is estimated to be , confirming that collimated outflows can
also be present in massive protostars. The proper motions of the outer lobes
should be measurable over timescales of a few years. Several fainter sources
detected in the region are most probably associated with other stars in a young
cluster.Comment: 9 pages, 2 figure
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