181 research outputs found
Impact of hypertension on infarct size in ST elevation myocardial infarction patients undergoing primary angioplasty.
Impact of multivessel disease on infarct size among STEMI patients undergoing primary angioplasty.
Deuterated water in the solar-type protostars NGC 1333 IRAS 4A and IRAS 4B
Aims. The aim of this paper is to study deuterated water in the solar-type
protostars NGC1333 IRAS4A and IRAS4B, to compare their HDO abundance
distribution with other star-forming regions, and to constrain their HDO/H2O
ratios. Methods. Using the Herschel/HIFI instrument as well as ground-based
telescopes, we observed several HDO lines covering a large excitation range
(Eup/k=22-168 K) towards these protostars and an outflow position. Non-LTE
radiative transfer codes were then used to determine the HDO abundance profiles
in these sources. Results. The HDO fundamental line profiles show a very broad
component, tracing the molecular outflows, in addition to a narrower emission
component and a narrow absorbing component. In the protostellar envelope of
NGC1333 IRAS4A, the HDO inner (T>100 K) and outer (T<100 K) abundances with
respect to H2 are estimated at 7.5x10^{-9} and 1.2x10^{-11}, respectively,
whereas, in NGC1333 IRAS4B, they are 1.0x10^{-8} and 1.2x10^{-10},
respectively. Similarly to the low-mass protostar IRAS16293-2422, an absorbing
outer layer with an enhanced abundance of deuterated water is required to
reproduce the absorbing components seen in the fundamental lines at 465 and 894
GHz in both sources. This water-rich layer is probably extended enough to
encompass the two sources as well as parts of the outflows. In the outflows
emanating from NGC1333 IRAS4A, the HDO column density is estimated at about
(2-4)x10^{13} cm^{-2}, leading to an abundance of about (0.7-1.9)x10^{-9}. An
HDO/H2O ratio between 7x10^{-4} and 9x10^{-2} is derived in the outflows. In
the warm inner regions of these two sources, we estimate the HDO/H2O ratios at
about 1x10^{-4}-4x10^{-3}. This ratio seems higher (a few %) in the cold
envelope of IRAS4A, whose possible origin is discussed in relation to formation
processes of HDO and H2O.Comment: 16 pages, 13 figure
Herschel observations of deuterated water towards Sgr B2(M)
Observations of HDO are an important complement for studies of water, because
they give strong constraints on the formation processes -- grain surfaces
versus energetic process in the gas phase, e.g. in shocks. The HIFI
observations of multiple transitions of HDO in Sgr~B2(M) presented here allow
the determination of the HDO abundance throughout the envelope, which has not
been possible before with ground-based observations only. The abundance
structure has been modeled with the spherical Monte Carlo radiative transfer
code RATRAN, which also takes radiative pumping by continuum emission from dust
into account. The modeling reveals that the abundance of HDO rises steeply with
temperature from a low abundance () in the outer envelope
at temperatures below 100~K through a medium abundance () in
the inner envelope/outer core, at temperatures between 100 and 200~K, and
finally a high abundance () at temperatures above 200~K in
the hot core.Comment: A&A HIFI special issue, accepte
The distribution of water in the high-mass star-forming region NGC 6334I
We present observations of twelve rotational transitions of H2O-16, H2O-18,
and H2O-17 toward the massive star-forming region NGC 6334 I, carried out with
Herschel/HIFI as part of the guaranteed time key program Chemical HErschel
Surveys of Star forming regions (CHESS). We analyze these observations to
obtain insights into physical processes in this region.
We identify three main gas components (hot core, cold foreground, and
outflow) in NGC 6334 I and derive the physical conditions in these components.
The hot core, identified by the emission in highly excited lines, shows a
high excitation temperature of 200 K, whereas water in the foreground component
is predominantly in the ortho- and para- ground states. The abundance of water
varies between 4 10^-5 (outflow) and 10^-8 (cold foreground gas). This
variation is most likely due to the freeze-out of water molecules onto dust
grains. The H2O-18/H2O-17 abundance ratio is 3.2, which is consistent with the
O-18/O-17 ratio determined from CO isotopologues. The ortho/para ratio in water
appears to be relatively low 1.6(1) in the cold, quiescent gas, but close to
the equilibrium value of three in the warmer outflow material (2.5(0.8)).Comment: 7 pages, 3 figures, accepted by A&
TIMASSS: The IRAS16293-2422 Millimeter And Submillimeter Spectral Survey. I. Observations, calibration and analysis of the line kinematics
While unbiased surveys observable from ground-based telescopes have
previously been obtained towards several high mass protostars, very little
exists on low mass protostars. To fill up this gap, we carried out a complete
spectral survey of the bands at 3, 2, 1 and 0.8 mm towards the solar type
protostar IRAS16293-2422. The observations covered about 200\,GHz and were
obtained with the IRAM-30m and JCMT-15m telescopes. Particular attention was
devoted to the inter-calibration of the obtained spectra with previous
observations. All the lines detected with more than 3 sigma and free from
obvious blending effects were fitted with Gaussians to estimate their basic
kinematic properties. More than 4000 lines were detected (with sigma \geq 3)
and identified, yielding a line density of approximatively 20 lines per GHz,
comparable to previous surveys in massive hot cores. The vast majority (~2/3)
of the lines are weak and due to complex organic molecules. The analysis of the
profiles of more than 1000 lines belonging 70 species firmly establishes the
presence of two distinct velocity components, associated with the two objects,
A and B, forming the IRAS16293-2422 binary system. In the source A, the line
widths of several species increase with the upper level energy of the
transition, a behavior compatible with gas infalling towards a ~1 Mo object.
The source B, which does not show this effect, might have a much lower central
mass of ~0.1 Mo. The difference in the rest velocities of both objects is
consistent with the hypothesis that the source B rotates around the source A.
This spectral survey, although obtained with single-dish telescope with a low
spatial resolution, allows to separate the emission from 2 different
components, thanks to the large number of lines detected. The data of the
survey are public and can be retrieved on the web site
http://www-laog.obs.ujf-grenoble.fr/heberges/timasss.Comment: 41 pages (26 pages of online Tables), 7 Tables and 6 Figure
Herschel observations of EXtra-Ordinary Sources: The Terahertz spectrum of Orion KL seen at high spectral resolution
We present the first high spectral resolution observations of Orion KL in the
frequency ranges 1573.4 - 1702.8 GHz (band 6b) and 1788.4 - 1906.8 GHz (band
7b) obtained using the HIFI instrument on board the Herschel Space Observatory.
We characterize the main emission lines found in the spectrum, which primarily
arise from a range of components associated with Orion KL including the hot
core, but also see widespread emission from components associated with
molecular outflows traced by H2O, SO2, and OH. We find that the density of
observed emission lines is significantly diminished in these bands compared to
lower frequency Herschel/HIFI bands.Comment: Accepted for publication in the Herschel HIFI special issue of
Astronomy and Astrophysics Letters, 5 pages, 3 figure
Herschel observations of extra-ordinary sources: Detection of Hydrogen Fluoride in absorption towards Orion~KL
We report a detection of the fundamental rotational transition of hydrogen
fluoride in absorption towards Orion KL using Herschel/HIFI. After the removal
of contaminating features associated with common molecules ("weeds"), the HF
spectrum shows a P-Cygni profile, with weak redshifted emission and strong
blue-shifted absorption, associated with the low-velocity molecular outflow. We
derive an estimate of 2.9 x 10^13 cm^-2 for the HF column density responsible
for the broad absorption component. Using our best estimate of the H2 column
density within the low-velocity molecular outflow, we obtain a lower limit of
~1.6 x 10^-10 for the HF abundance relative to hydrogen nuclei, corresponding
to 0.6% of the solar abundance of fluorine. This value is close to that
inferred from previous ISO observations of HF J=2--1 absorption towards Sgr B2,
but is in sharp contrast to the lower limit of 6 x 10^-9 derived by Neufeld et
al. (2010) for cold, foreground clouds on the line of sight towards G10.6-0.4.Comment: 5 pages, 3 figures, paper to be published in the Herschel special
issue of A&A letter
First detection of ND in the solar-mass protostar IRAS16293-2422
In the past decade, much progress has been made in characterising the
processes leading to the enhanced deuterium fractionation observed in the ISM
and in particular in the cold, dense parts of star forming regions such as
protostellar envelopes. Very high molecular D/H ratios have been found for
saturated molecules and ions. However, little is known about the deuterium
fractionation in radicals, even though simple radicals often represent an
intermediate stage in the formation of more complex, saturated molecules. The
imidogen radical NH is such an intermediate species for the ammonia synthesis
in the gas phase. Herschel/HIFI represents a unique opportunity to study the
deuteration and formation mechanisms of such species, which are not observable
from the ground. We searched here for the deuterated radical ND in order to
determine the deuterium fractionation of imidogen and constrain the deuteration
mechanism of this species. We observed the solar-mass Class 0 protostar
IRAS16293-2422 with the heterodyne instrument HIFI as part of the Herschel key
programme CHESS (Chemical HErschel Surveys of Star forming regions). The
deuterated form of the imidogen radical ND was detected and securely identified
with 2 hyperfine component groups of its fundamental transition in absorption
against the continuum background emitted from the nascent protostar. The 3
groups of hyperfine components of its hydrogenated counterpart NH were also
detected in absorption. We derive a very high deuterium fractionation with an
[ND]/[NH] ratio of between 30 and 100%. The deuterium fractionation of imidogen
is of the same order of magnitude as that in other molecules, which suggests
that an efficient deuterium fractionation mechanism is at play. We discuss two
possible formation pathways for ND, by means of either the reaction of N+ with
HD, or deuteron/proton exchange with NH.Comment: Accepted; To appear in A&A Herschel/HIFI Special Issu
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