215 research outputs found
Spectroscopic parameters for silacyclopropynylidene, SiC, from extensive astronomical observations toward CW Leo (IRC +10216) with the Herschel satellite
A molecular line survey has been carried out toward the carbon-rich
asymptotic giant branch star CW Leo employing the HIFI instrument on board of
the Herschel satellite. Numerous features from 480 GHz to beyond 1100 GHz could
be assigned unambiguously to the fairly floppy SiC molecule. However,
predictions from laboratory data exhibited large deviations from the observed
frequencies even after some lower frequency data from this survey were
incorporated into a fit. Therefore, we present a combined fit of all available
laboratory data together with data from radio-astronomical observations.Comment: 7 pages, 1 figure, J. Mol. Spectrosc., appeared; CDMS links corrected
(version 2; current version: 3; may be updated later this year
The 35Cl/37Cl isotopic ratio in dense molecular clouds: HIFI observations of hydrogen chloride towards W3A
We report on the detection with the HIFI instrument on board the Herschel
satellite of the two hydrogen chloride isotopologues, H35Cl and H37Cl, towards
the massive star-forming region W3A. The J=1-0 line of both species was
observed with receiver 1b of the HIFI instrument at 625.9 and 624.9 GHz. The
different hyperfine components were resolved. The observations were modeled
with a non-local, non-LTE radiative transfer model that includes hyperfine line
overlap and radiative pumping by dust. Both effects are found to play an
important role in the emerging intensity from the different hyperfine
components. The inferred H35Cl column density (a few times 1e14 cm^-2), and
fractional abundance relative to H nuclei (~7.5e^-10), supports an upper limit
to the gas phase chlorine depletion of ~200. Our best-fit model estimate of the
H35Cl/H37Cl abundance ratio is ~2.1+/-0.5, slightly lower, but still compatible
with the solar isotopic abundance ratio (~3.1). Since both species were
observed simultaneously, this is the first accurate estimation of the
[35Cl]/[37Cl] isotopic ratio in molecular clouds. Our models indicate that even
for large line opacities and possible hyperfine intensity anomalies, the H35Cl
and H37Cl J=1-0 integrated line-intensity ratio provides a good estimate of the
35Cl/37Cl isotopic abundance ratio.Comment: Accepted for publication in Astronomy and Astrophysics (Herschel
special issue
Detection of C3O in IRC+10216: Oxygen-Carbon chain chemistry in the outer envelope
The oxygen-bearing species C3O has been identified in the circumstellar envelope of the carbon star IRC +10216. The J = 8-->7, 9-->8, 10-->9, 14-->13, and 15-->14 transitions were detected at 2 and 3 mm using the Arizona Radio Observatoryâs 12 m telescope. Measurements of the J = 9-->8, 10-->9, and 12-->11 lines were simultaneously conducted at the IRAM 30 m telescope. The line profiles of C3O are roughly U-shaped, indicating an extended shell distribution for this molecule in IRC +10216. The total column density derived for C3O is 1.2x10^12 cm^-2, at least an order of magnitude higher than that predicted by current chemical models. However, a revised model that includes reactions of atomic oxygen with carbon-chain radicals, such as l-C3H and C4, can reproduce the observed abundance. This model also predicts that C3O arises from a shell source with an outer radius near
r ⌠30", consistent with the observations. These results suggest that gas phase neutral-neutral chemistry may be
producing the oxygen-bearing molecules present in the outer envelope of IRC +10216.This material is based on work supported by the National Aeronautics and Space Administration through the NASA Astrobiology
Institute under Cooperative Agreement CAN-02-OSS-02 issued through the Office of Space Science. We also acknowledge support from Spanish MEC under project AYA2003-2785 and from "Comunidad de Madrid" under
PRICIT project S-0505/ESP-0237 (ASTROCAM). E. D. T. thanks NSF for a graduate research fellowship, and M. A. acknowledges Spanish MEC for a predoctoral grant AP2003-4619.Peer reviewe
Toward a clinical practice guide in pharmacogenomics testing for functional polymorphisms of drug-metabolizing enzymes. Gene/drug pairs and barriers perceived in Spain
The development of clinica lpractice recommendations or
guidelines for the clinical use of biomarkers is an issue of great importance withr regard to adverse drug reactions.The poten-tial of pharmacogenomicbiomarkers has been extensively investigated in recent years.However,several barriers to implementing the use of pharmacogenomics testing exist.We conducted a survey among members of the Spanish Societies of Pharmacology and Clinical Pharmacology to obtain information about the perception of such barriers and to compare the perceptions of participants about the relative importance of majorgene/drug pairs.Of 11 potential barriers,the highest importance was attributed to lack of institutional support for pharmacogenomic stesting,and to the issues related to the lack of guidelines.Of the proposed gene/drug pairs the highest importance was assigned to HLA-B/abacavir, UGT1A1/irinotecan, and CYP2D6/tamoxifen.In this perspective article,we compare the relative importance of 29 gene/drugpairs in the Spanish study with that of the same pairs in the American Society for Clinical Pharmacology and Therapeutic sstudy,and we provide suggestions and areas of focus to develop a guide for clinical practice in pharmacogenomics testingThe work in the authorâs laboratory is financed by Grants
PS09/00943, PS09/00469, RETICS RIRAAF RD07/0064/0016,
and CIBERehd from Instituto de Salud CarlosIII,Madrid,
Spain, and by Grants GR10068 from Junta de Extremadura,
Spain. Financed in part with FEDER funds from the European
Unio
Variación genética de Pinus pinaster Ait. : aplicación a la identificación y caracterización del material forestal de reproducción
Documento apresentado no III Congreso Forestal Español que decorreu em Granada de 25 a 28 de Setembro de 2001.El estudio com marcadores moleculares de las espĂ©cies forestales permite analizar la distribuciĂłn y estructura de la diversidad genĂ©tica. Se han analizado 47 poblaciones de pino negral (Pinus pinaster Ait.) com 16 loci isoenzimĂĄticos. Del conjunto inicial de 16 loci se han seleccionado aquellos com mayor polimorfismo y potencialidad para la identificaciĂłn del Material Forestal de ReproducciĂłn (8 loci). Este conjunto de sistemas enzimĂĄticos de evaluaciĂłn se ha utilizado para estimar la diversidad genĂ©tica poblacional de la espĂ©cie. Posteriormente, las poblaciones fueram agrupadas segĂșn su situaciĂłn geogrĂĄfica y nĂvel de diversidad realizĂĄndose un AnĂĄlisis CanĂłnico Discriminante. A escala global se distinguen trĂȘs grandes grupos dentro del ĂĄrea de distribuciĂłn natural de la espĂ©cie; norte de Ăfrica, PenĂnsula IbĂ©rica y sureste de Francia y Italia podiĂ©ndose subdividir las poblaciones ibĂ©ricas de pino negral en trĂȘs grupos com sentido geogrĂĄfico: grupo este, grupo sureste e grupo noroeste. La utilizaciĂłn de los marcadores isoenzimĂĄticos se hĂĄ mostrado de gran utilidad para identificar y certificar Material Forestal de ReproducciĂłn (MFR)
Evidence for CO depletion in the inner regions of gas-rich protoplanetary disks
We investigate the physical properties and spatial distribution of Carbon
Monoxide (CO) gas in the disks around the Herbig Ae/Be stars HD 97048 and HD
100546.
Using high-spectral-resolution 4.588-4.715 m spectra containing
fundamental CO emission taken with CRIRES on the VLT, we probe the
circumstellar gas and model the kinematics of the emission lines. By using
spectro-astrometry on the spatially resolved targets, we constrain the physical
size of the emitting regions in the disks. We resolve, spectrally and
spatially, the emission of the CO v(1-0) vibrational band and the
CO and vibrational bands in both targets,
as well as the CO band in HD 100546. Modeling of the CO emission
with a homogeneous disk in Keplerian motion, yields a best fit with an inner
and outer radius of the CO emitting region of 11 and 100 AU for HD
97048. HD 100546 is not fit well with our model, but we derive a lower limit on
the inner radius of 8 AU. The fact that gaseous [OI] emission was previously
detected in both targets at significantly smaller radii suggests that CO may be
effectively destroyed at small radii in the surface layers of these disksComment: v2: Letter format has been changed to Paper format; Change in the
focus of the paper towards CO depletion; Major changes in text; Change of
title. Submitted to A&A, 14/10/2008. Accepted by A&A, 17/04/200
HIFI detection of HF in the carbon star envelope IRC +10216
We report the detection of emission in the J=1-0 rotational transition of
hydrogen fluoride (HF), together with observations of the J=1-0 to J=3-2
rotational lines of H35Cl and H37Cl, towards the envelope of the carbon star
IRC +10216. High-sensitivity, high-spectral resolution observations have been
carried out with the HIFI instrument on board Herschel, allowing us to resolve
the line profiles and providing insights into the spatial distribution of the
emission. Our interpretation of the observations, with the use of radiative
transfer calculations, indicates that both HF and HCl are formed in the inner
regions of the envelope close to the AGB star. Thermochemical equilibrium
calculations predict HF and HCl to be the major reservoirs of fluorine and
chlorine in the atmospheres of AGB stars. The abundances relative to H2 derived
for HF and HCl, 8e-9 and 1e-7 respectively, are substantially lower than those
predicted by thermochemical equilibrium, indicating that F and Cl are likely
affected by significant depletion onto dust grains, although some chlorine may
be in the form of atomic Cl. The H35Cl/H37Cl abundance ratio is 3.3 +/- 0.3.
The low abundance derived for HF in IRC +10216 makes it likely that the
fluorine abundance is not enhanced over the solar value by nucleosynthesis in
the AGB star, although this conclusion may not be robust because the HF
abundance we derive is a lower limit to the elemental abundance of F. These
observations suggest that both HF and HCl should be detectable through low J
rotational transitions in other evolved stars.Comment: Accepted for publication in A&A Letter
Ultra-deep 31.0-50.3 GHz spectral survey of IRC+10216
51 pags., 43 figs., 3 tabs.Context. The carbon-rich envelope of the asymptotic giant branch star CW Leo, IRC+10216, is one of the richest molecular sources in the sky. Available spectral surveys below 51 GHz are more than 25 years old, and new work is needed. Aims. Characterizing the rich molecular content of this source, specially for heavy species, requires carrying out very sensitive spectral surveys at low frequencies. In particular, we have achieved an rms in the range 0.2-0.6mK per MHz. Methods. Long Q band (31.0-50.3 GHz) single-dish integrations were carried out with the Yebes-40m telescope using specifically built receivers. The most recent line catalogs were used to identify the lines. Results. The data contain 652 spectral features, corresponding to 713 transitions from 81 species (we count the isomers, isotopologs, and ortho/para species separately). Only 57 unidentified lines remain with signal-to-noise ratios â€3. Some new species and/or vibrational modes have been discovered for the first time with this survey. Conclusions. This IRC+10216 spectral survey is by far the most sensitive survey carried out to date in the Q band. It therefore provides the most complete view of IRC+10216 from 31.0 to 50.3 GHz, giving unique information about its molecular content, especially for heavy species. Rotational diagrams built from the data provide valuable information about the physical conditions and chemical content of this circumstellar envelope.We thank Ministerio de Ciencia e InnovaciĂłn of Spain
for funding support through projects PID2019-106110GB-I00, PID2019-
107115GB-C21/AEI/10.13039/501100011033, PID2019-106235GB-I00, and
grant FJCI-2016-27983 for CB. We also thank ERC for funding through grant
ERC-2013-Syg-610256-NANOCOSMOS. M.A. thanks MICIU for grant RyC2014-16277
Time Variability of Molecular Line Emission in IRC+10216
We present the results of monitoring the molecular emission of the C-rich AGB star IRC+10216 over 3 years with the Herschel Space Observatory. Observations of rotational transitions of various vibrational levels of CO, ^(13)CO, CS, CCH, H_2O, SiO, SiS, SiC_2, HCN and HNC have been collected with the HIFI, PACS and SPIRE instruments over multiple epochs. The intensity monitoring shows strong and periodic variations of most of the observed molecules, often with differential behavior depending on the transition level (larger variation at higher J), and generally enhanced modulations in the vibrational modes of some of these molecules (e.g. HCN). These results show that the effect of IR pumping through the different vibrational levels on the emergent line profiles of a given transition can be really significant. This implies that the IR radiation field of the circumstellar envelope and its time variation has to be taken into account in any radiative transfer model in order to derive accurately the physico-chemical structure of the envelope
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