1,464 research outputs found

    Direct Detection of a (Proto)Binary-Disk System in IRAS 20126+4104

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    We report the direct detection of a binary/disk system towards the high-mass (proto)stellar object IRAS20126+4104 at infrared wavengths. The presence of a multiple system had been indicated by the precession of the outflow and the double jet system detected earlier at cm-wavelengths. Our new K, L' & M' band infrared images obtained with the UKIRT under exceptional seeing conditions on Mauna Kea are able to resolve the central source for the first time, and we identify two objects separated by ~ 0.5'' (850 AU). The K and L' images also uncover features characteristic of a nearly edge-on disk, similar to many low mass protostars with disks: two emission regions oriented along an outflow axis and separated by a dark lane. The peaks of the L' & M' band and mm-wavelength emission are on the dark lane, presumably locating the primary young star. The thickness of the disk is measured to be ~ 850 AU for radii < 1000 AU. Approximate limits on the NIR magnitudes of the two young stars indicate a high-mass system, although with much uncertainty. These results are a demonstration of the high-mass nature of the system, and the similarities of the star-formation process in the low-mass and high-mass regimes viz. the presence of a disk-accretion stage. The companion is located along the dark lane, consistent with it being in the equatorial/disk plane, indicating a disk-accretion setting for massive, multiple, star-formation.Comment: 12 pages, 3 figures (1 pseudo colour), 1 table; colour figure replaced with jpg file; to be published in ApJL; (back after temoprary withdrawal due to non-scientific reasons.

    Submillimeter Observations of The Isolated Massive Dense Clump IRAS 20126+4104

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    We used the CSO 10.4 meter telescope to image the 350 micron and 450 micron continuum and CO J=6-5 line emission of the IRAS 20126+4104 clump. The continuum and line observations show that the clump is isolated over a 4 pc region and has a radius of ~ 0.5 pc. Our analysis shows that the clump has a radial density profile propto r ^{-1.2} for r <~ 0.1 pc and has propto r^{-2.3} for r >~ 0.1 pc which suggests the inner region is infalling, while the infall wave has not yet reached the outer region. Assuming temperature gradient of r^{-0.35}, the power law indices become propto r ^{-0.9} for r < ~0.1 pc and propto r^{-2.0} for r >~ 0.1 pc. Based on a map of the flux ratio of 350micron/450micron, we identify three distinct regions: a bipolar feature that coincides with the large scale CO bipolar outflow; a cocoon-like region that encases the bipolar feature and has a warm surface; and a cold layer outside of the cocoon region. The complex patterns of the flux ratio map indicates that the clump is no longer uniform in terms of temperature as well as dust properties. The CO emission near the systemic velocity traces the dense clump and the outer layer of the clump shows narrow line widths (< ~3 km/s). The clump has a velocity gradient of ~ 2 km/s pc^{-1}, which we interpret as due to rotation of the clump, as the equilibrium mass (~ 200 Msun) is comparable to the LTE mass obtained from the CO line. Over a scale of ~ 1 pc, the clump rotates in the opposite sense with respect to the >~ 0.03 pc disk associated with the (proto)star. This is one of four objects in high-mass and low-mass star forming regions for which a discrepancy between the rotation sense of the envelope and the core has been found, suggesting that such a complex kinematics may not be unusual in star forming regions.Comment: 34 pages, 13 figures, Accepted for publication in the Ap

    Velocity and magnetic fields within 1000 AU from a massive YSO

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    We want to study the velocity and magnetic field morphology in the vicinity (<1000 AU) of a massive young stellar object (YSO), at very high spatial resolution (10-100 AU). We performed milli-arcsecond polarimetric observations of the strong CH3OH maser emission observed in the vicinity of an O-type YSO, in G023.01-00.41. We have combined this information with the velocity field of the CH3OH masing gas previously measured at the same angular resolution. We analyse the velocity and magnetic fields in the reference system defined by the direction of the molecular outflow and the equatorial plane of the hot molecular core at its base, as recently observed on sub-arcsecond scales. We provide a first detailed picture of the gas dynamics and magnetic field configuration within a radius of 2000 AU from a massive YSO. We have been able to reproduce the magnetic field lines for the outer regions (>600 AU) of the molecular envelope, where the magnetic field orientation shows a smooth change with the maser cloudlets position (0.2 degree/AU). Overall, the velocity field vectors well accommodate with the local, magnetic field direction, but still show an average misalignment of 30 degrees. We interpret this finding as the contribution of a turbulent velocity field of about 3.5 km/s, responsible for braking up the alignment between the velocity and magnetic field vectors. We do resolve different gas flows which develop both along the outflow axis and across the disk plane, with an average speed of 7 km/s. In the direction of the outflow axis, we establish a collimation of the gas flow, at a distance of about 1000 AU from the disk plane. In the disk region, gas appears to stream outward along the disk plane for radii greater than 500-600 AU, and inward for shorter radii.Comment: 7 pages, 4 figures, 1 table, accepted by Astronomy & Astrophysic

    Socioeconomic differentials in the immediate mortality effects of the national Irish smoking ban

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    This article has been made available through the Brunel Open Access Publishing Fund.Background: Consistent evidence has demonstrated that smoking ban policies save lives, but impacts on health inequalities are uncertain as few studies have assessed post-ban effects by socioeconomic status (SES) and findings have been inconsistent. The aim of this study was to assess the effects of the national Irish smoking ban on ischemic heart disease (IHD), stroke, and chronic obstructive pulmonary disease (COPD) mortality by discrete and composite SES indicators to determine impacts on inequalities. Methods: Census data were used to assign frequencies of structural and material SES indicators to 34 local authorities across Ireland with a 2000–2010 study period. Discrete indicators were jointly analysed through principal component analysis to generate a composite index, with sensitivity analyses conducted by varying the included indicators. Poisson regression with interrupted time-series analysis was conducted to examine monthly age and gender-standardised mortality rates in the Irish population, ages ≥35 years, stratified by tertiles of SES indicators. All models were adjusted for time trend, season, influenza, and smoking prevalence. Results: Post-ban mortality reductions by structural SES indicators were concentrated in the most deprived tertile for all causes of death, while reductions by material SES indicators were more equitable across SES tertiles. The composite indices mirrored the results of the discrete indicators, demonstrating that post-ban mortality decreases were either greater or similar in the most deprived when compared to the least deprived for all causes of death. Conclusions: Overall findings indicated that the national Irish smoking ban reduced inequalities in smoking-related mortality. Due to the higher rates of smoking-related mortality in the most deprived group, even equitable reductions across SES tertiles resulted in decreases in inequalities. The choice of SES indicator was influential in the measurement of effects, underscoring that a differentiated analytical approach aided in understanding the complexities in which structural and material factors influence mortality

    CultureLabs: Cultural heritage and digital technology at the service of social innovation

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    Studies and practice in the cultural field have long acknowledged the importance of participatory approaches for engaging visitors of cultural institutions, however, it is only recently that we are talking about steps to connecting institutional heritage with civic initiatives that can aid social cohesion and community empowerment. In dialogue with ongoing practices in this context, CultureLabs aims to develop novel methodologies and digital tools that can facilitate the organisation and wider deployment of participatory projects around cultural her - itage, focusing on the social inclusion of disadvantaged groups, and particularly of migrant communities. As a first step in this process, the CultureLabs team has conducted a series of interviews and surveys with the aim to identify and analyse the organisational needs and lessons learnt by different actors from the cultural, social, educational and public administration fields as well as the needs and viewpoints of different migrant communities. These needs have guided the design of an innovative online platform which seeks to offer a number of services for supporting more efficient and participatory governance of cultural heritage on one hand and for enabling inclusive and creative interactions with digital cultural heritage on the other. The CultureLabs platform will allow multiple and diverse stakeholders to discover and combine differ - ent resources and elements of best practices, the "ingredients", in order to form new "recipes" for social innovation according to their own needs and objectives

    VLA observations of candidate high-mass protostellar objects at 7 mm

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    We present radio continuum observations at 7 mm made using the Very Large Array towards three massive star forming regions thought to be in very early stages of evolution selected from the sample of Sridharan et al. (2002). Emission was detected towards all three sources (IRAS 18470-0044, IRAS 19217+1651 and IRAS 23151+5912). We find that in all cases the 7 mm emission corresponds to thermal emission from ionized gas. The regions of ionized gas associated with IRAS 19217+1651 and IRAS 23151+5912 are hypercompact with diameters of 0.009 and 0.0006 pc, and emission measures of 7.0 x 10^8 and 2.3 x 10^9 pc cm^(-6), respectively.Comment: 17 pages, 5 figures, accepted by The Astronomical Journa

    CARPET: a web-based package for the analysis of ChIP-chip and expression tiling data

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    Summary: CARPET (Collection of Automated Routine Programs for Easy Tiling) is a set of Perl, Python and R scripts, integrated on the Galaxy2 web-based platform, for the analysis of ChIP-chip and expression tiling data, both for standard and custom chip designs. CARPET allows rapid experimental data entry, simple quality control, normalization, easy identification and annotation of enriched ChIP-chip regions, detection of the absolute or relative transcriptional status of genes assessed by expression tiling experiments and, more importantly, it allows the integration of ChIP-chip and expression data. Results can be visualized instantly in a genomic context within the UCSC genome browser as graph-based custom tracks through Galaxy2. All generated and uploaded data can be stored within sessions and are easily shared with other users. Availability: http://bio.ifom-ieo-campus.it/galaxy Contacts: [email protected] lucilla.luzi@if om-ieo-campus.i

    Radio Continuum and Recombination Line Study of UC HII Regions with Extended Envelopes

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    We have carried out 21 cm radio continuum observations of 16 UC HII regions using the VLA (D-array) in search of associated extended emission. We have also observed H76α_\alpha recombination line towards all the sources and He76α_\alpha line at the positions with strong H76α_\alpha line emission. The UC HII regions have simple morphologies and large (>10) ratios of single-dish to VLA fluxes. Extended emission was detected towards all the sources. The extended emission consists of one to several compact components and a diffuse extended envelope. All the UC HII regions but two are located in the compact components, where the UC HII regions always correspond to their peaks. The compact components with UC HII regions are usually smaller and denser than those without UC HII regions. Our recombination line observations indicate that the ultracompact, compact, and extended components are physically associated. The UC HII regions and their associated compact components are likely to be ionized by the same sources on the basis of the morphological relations mentioned above. This suggests that almost all of the observed UC HII regions are not `real' UC HII regions and that their actual ages are much greater than their dynamical age (<10000 yr). We find that most of simple UC HII regions previously known have large ratios of single-dish to VLA fluxes, similar to our sources. Therefore, the `age problem' of UC HII regions does not seem to be as serious as earlier studies argued. We present a simple model that explains extended emission around UC HII regions. Some individual sources are discussed.Comment: 29 pages, 28 postscript figures, Accepted for publication in Ap
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