1,464 research outputs found
Direct Detection of a (Proto)Binary-Disk System in IRAS 20126+4104
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
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
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
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
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
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
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
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 H76 recombination line towards all the sources and
He76 line at the positions with strong H76 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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