170 research outputs found
High Spectral and Spatial Resolution Observations of the PDR Emission in the NGC2023 Reflection Nebula with SOFIA and APEX
We have mapped the NGC 2023 reflection nebula in [CII] and CO(11--10) with
the heterodyne receiver GREAT on SOFIA and obtained slightly smaller maps in
13CO(3--2), CO(3--2), CO(4--3), CO(6--5), and CO(7--6) with APEX in Chile. We
use these data to probe the morphology, kinematics, and physical conditions of
the C II region, which is ionized by FUV radiation from the B2 star HD37903.
The [CII] emission traces an ellipsoidal shell-like region at a position angle
of ~ -50 deg, and is surrounded by a hot molecular shell. In the southeast,
where the C II region expands into a dense, clumpy molecular cloud ridge, we
see narrow and strong line emission from high-J CO lines, which comes from a
thin, hot molecular shell surrounding the [CII] emission. The [CII] lines are
broader and show photo evaporating gas flowing into the C II region. Based on
the strength of the [13CII] F=2--1 line, the [CII] line appears to be somewhat
optically thick over most of the nebula with an optical depth of a few. We
model the physical conditions of the surrounding molecular cloud and the PDR
emission using both RADEX and simple PDR models. The temperature of the CO
emitting PDR shell is ~ 90 -- 120 K, with densities of 10^5 -- 10^6 cm^-3, as
deduced from RADEX modeling. Our PDR modeling indicates that the PDR layer
where [CII] emission dominates has somewhat lower densities, 10^4 to a few
times 10^5 cm^-3Comment: Accepted by A&
Abundant Z-cyanomethanimine in the interstellar medium: paving the way to the synthesis of adenine
We report the first detection in the interstellar medium of the Z-isomer of
cyanomethanimine (HNCHCN), an HCN dimer proposed as precursor of adenine. We
identified six transitions of Z-cyanomethanimine, along with five transitions
of E-cyanomethanimine, using IRAM 30m observations towards the Galactic Center
quiescent molecular cloud G+0.693. The Z-isomer has a column density of
(2.00.6)10 cm and an abundance of
1.510. The relative abundance ratio between the isomers is
[Z/E]6. This value cannot be explained by the two chemical formation
routes previously proposed (gas-phase and grain surface), which predicts
abundances ratios between 0.9 and 1.5. The observed [Z/E] ratio is in good
agreement with thermodynamic equilibrium at the gas kinetic temperature
(130210 K). Since isomerization is not possible in the ISM, the two species
may be formed at high temperature. New chemical models, including surface
chemistry on dust grains and gas-phase reactions, should be explored to explain
our findings. Whatever the formation mechanism, the high abundance of Z-HNCHCN
shows that precursors of adenine are efficiently formed in the ISM.Comment: Accepted in Monthly Notices of the Royal Astronomical Society Letter
Complex organic molecules in the Galactic Centre: the N-bearing family
We present an unbiased spectral line survey toward the Galactic Centre (GC)
quiescent giant molecular cloud (QGMC), G+0.693 using the GBT and IRAM 30
telescopes. Our study highlights an extremely rich organic inventory of
abundant amounts of nitrogen (N)-bearing species in a source without signatures
of star formation. We report the detection of 17 N-bearing species in this
source, of which 8 are complex organic molecules (COMs). A comparison of the
derived abundances relative to H is made across various galactic and
extragalactic environments. We conclude that the unique chemistry in this
source is likely to be dominated by low-velocity shocks with X-rays/cosmic rays
also playing an important role in the chemistry. Like previous findings
obtained for O-bearing molecules, our results for N-bearing species suggest a
more efficient hydrogenation of these species on dust grains in G+0.693 than in
hot cores in the Galactic disk, as a consequence of the low dust temperatures
coupled with energetic processing by X-ray/cosmic ray radiation in the GC.Comment: 24 pages, 23 figures, 7 tables, accepted for publication in MNRA
Chemical Features in the Circumnuclear Disk of the Galactic Center
The circumnuclear disk (CND) of the Galactic Center is exposed to many
energetic phenomena coming from the supermassive black hole Sgr A* and stellar
activities. These energetic activities can affect the chemical composition in
the CND by the interaction with UV-photons, cosmic-rays, X-rays, and shock
waves. We aim to constrain the physical conditions present in the CND by
chemical modeling of observed molecular species detected towards it. We
analyzed a selected set of molecular line data taken toward a position in the
southwest lobe of the CND with the IRAM 30m and APEX 12-meter telescopes and
derived the column density of each molecule using a large velocity gradient
(LVG) analysis. The determined chemical composition is compared with a
time-dependent gas-grain chemical model based on the UCL\_CHEM code that
includes the effects of shock waves with varying physical parameters. Molecules
such as CO, HCN, HCO, HNC, CS, SO, SiO, NO, CN, HCO, HCN,
NH and HO are detected and their column densities are obtained.
Total hydrogen densities obtained from LVG analysis range between and cm and most species indicate values around
several cm, which are lower than values corresponding to
the Roche limit, which shows that the CND is tidally unstable. The chemical
models show good agreement with the observations in cases where the density is
cm, the cosmic-ray ionization rate is high, s, or shocks with velocities km s have occurred.
Comparison of models and observations favors a scenario where the cosmic-ray
ionization rate in the CND is high, but precise effects of other factors such
as shocks, density structures, UV-photons and X-rays from the Sgr A* must be
examined with higher spatial resolution data.Comment: 17 Pages, 13 figures, accepted for publication in A&
Influencia del riego deficitario controlado precosecha sobre la calidad de la cereza ´Prime Giant`
El uso de redes de sensores para el manejo del riego deficitario controlado (RDC) en
cerezo puede incidir en la mejora de la productividad del agua, calidad de la fruta y en su
comportamiento poscosecha, al permitir el conocimiento y control del estado hÃdrico del
suelo y árbol en todo momento.
En el primer año de ensayo, el riego deficitario aplicado en precosecha para
satisfacer el 85% de las necesidades máximas del cultivo (ETcg) permitió un ahorro de agua
del 17% (380 m3 ha-1) respecto al tratamiento control, que se regó al 110% de la ETcg. Este
déficit hÃdrico ligero no afectó a la producción (16,13 t ha-1) e incluso mejoró la calidad del
fruto. AsÃ, en el momento de la cosecha (t0) los frutos bajo déficit ligero presentaron matices
más rojos y mayor acidez que los de riego completo. Esta mayor acidez no afectó al Ãndice
de madurez debido a la compensación por sólidos solubles totales (SST). El carácter de
mayor acidez perduró tras 30 dÃas de conservación en frio (t1) y 5 dÃas de simulación de las
condiciones de comercialización (t2). Igualmente, los frutos bajo déficit hÃdrico presentaron
una tendencia a menores pérdidas de peso por deshidratación a finales de los periodos de
conservación en frio y de simulación de la comercialización.Ministerio de EconomÃa y Competitividad AGL2013-49047-C2-1
Spectral imaging of the Central Molecular Zone in multiple 3-mm molecular lines
We have mapped 20 molecular lines in the Central Molecular Zone (CMZ) around
the Galactic Centre, emitting from 85.3 to 93.3 GHz. This work used the 22-m
Mopra radio telescope in Australia, equipped with the 8-GHz bandwidth UNSW-MOPS
digital filter bank, obtaining \sim 2 km/s spectral and \sim 40 arcsec spatial
resolution. The lines measured include emission from the c-C3H2, CH3CCH, HOCO+,
SO, H13CN, H13CO+, SO, H13NC, C2H, HNCO, HCN, HCO+, HNC, HC3N, 13CS and N2H+
molecules. The area covered is Galactic longitude -0.7 to 1.8 deg. and latitude
-0.3 to 0.2 deg., including the bright dust cores around Sgr A, Sgr B2, Sgr C
and G1.6-0.025. We present images from this study and conduct a principal
component analysis on the integrated emission from the brightest 8 lines. This
is dominated by the first component, showing that the large-scale distribution
of all molecules are very similar. We examine the line ratios and optical
depths in selected apertures around the bright dust cores, as well as for the
complete mapped region of the CMZ. We highlight the behaviour of the bright
HCN, HNC and HCO+ line emission, together with that from the 13C isotopologues
of these species, and compare the behaviour with that found in extra-galactic
sources where the emission is unresolved spatially. We also find that the
isotopologue line ratios (e.g. HCO+/H13CO+) rise significantly with increasing
red-shifted velocity in some locations. Line luminosities are also calculated
and compared to that of CO, as well as to line luminosities determined for
external galaxies.Comment: 27 pages, 15 figures, 12 tables, accepted by MNRA
A functional IL1RL1 variant regulates corticosteroid-induced sST2 expression in ulcerative colitis
Indexación: Web of Science; Scopus.The ST2/IL33 signalling pathway has been associated with ulcerative colitis (UC). ST2, encoded by the IL1RL1 gene, is expressed as both a membrane-anchored receptor (ST2L) activated by IL33 and as a soluble receptor (sST2) with anti-inflammatory properties. In UC patients, sST2 is further increased by corticosteroid treatment; however, the glucocorticoid-mediated molecular regulation remains unknown. We therefore tested whether genetic variants in the IL1RL1 distal promoter are involved in UC and affect glucocorticoid-mediated ST2 expression. Serum ST2 levels and genetic variants in the IL1RL1 distal promoter were examined by ELISA and PCR sequencing in UC patients receiving corticosteroids. Glucocorticoid-mediated ST2 production was evaluated in intestinal mucosa cultures. Molecular regulation of glucocorticoid-mediated ST2 was assessed by RT-qPCR, ChIP assay and luciferase reporter assay. Dexamethasone effect on ST2 transcript expression was analyzed in leukocytes and related to IL1RL1 variants. Sequencing of a distal IL1RL1 promoter region demonstrated that SNPs rs6543115(C) and rs6543116(A) are associated with increased sST2 in UC patients on corticosteroids. Dexamethasone up-regulated sST2 transcription through interaction with the glucocorticoid-response element (GRE) carrying rs6543115(C) variant. Our data indicate that IL1RL1 SNPs rs6543115(C) confer susceptibility to UC and is contained in the GRE, which may modulate glucocorticoid-induced sST2 expression.https://www.nature.com/articles/s41598-017-10465-
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