713 research outputs found
Millimeter imaging of HD 163296: probing the disk structure and kinematics
We present new multi-wavelength millimeter interferometric observations of
the Herbig Ae star HD 163296 obtained with the IRAM/PBI, SMA and VLA arrays
both in continuum and in the 12CO, 13CO and C18O emission lines. Gas and dust
properties have been obtained comparing the observations with self-consistent
disk models for the dust and CO emission. The circumstellar disk is resolved
both in the continuum and in CO. We find strong evidence that the circumstellar
material is in Keplerian rotation around a central star of 2.6 Msun. The disk
inclination with respect to the line of sight is 46+-4 deg with a position
angle of 128+-4 deg. The slope of the dust opacity measured between 0.87 and 7
mm (beta=1) confirms the presence of mm/cm-size grains in the disk midplane.
The dust continuum emission is asymmetric and confined inside a radius of 200
AU while the CO emission extends up to 540 AU. The comparison between dust and
CO temperature indicates that CO is present only in the disk interior. Finally,
we obtain an increasing depletion of CO isotopomers from 12CO to 13CO and C18O.
We argue that these results support the idea that the disk of HD 163296 is
strongly evolved. In particular, we suggest that there is a strong depletion of
dust relative to gas outside 200 AU; this may be due to the inward migration of
large bodies that form in the outer disk or to clearing of a large gap in the
dust distribution by a low mass companion.Comment: Accepted for publication on A&A, 16 page
The complex morphology of the young disk MWC 758: Spirals and dust clumps around a large cavity
We present Atacama Large Millimeter Array (ALMA) observations at an angular
resolution of 0.1-0.2" of the disk surrounding the young Herbig Ae star MWC
758. The data consist of images of the dust continuum emission recorded at 0.88
millimeter, as well as images of the 13CO and C18O J = 3-2 emission lines. The
dust continuum emission is characterized by a large cavity of roughly 40 au in
radius which might contain a mildly inner warped disk. The outer disk features
two bright emission clumps at radii of about 47 and 82 au that present
azimuthal extensions and form a double-ring structure. The comparison with
radiative transfer models indicates that these two maxima of emission
correspond to local increases in the dust surface density of about a factor 2.5
and 6.5 for the south and north clumps, respectively. The optically thick 13CO
peak emission, which traces the temperature, and the dust continuum emission,
which probes the disk midplane, additionally reveal two spirals previously
detected in near-IR at the disk surface. The spirals seen in the dust continuum
emission present, however, a slight shift of a few au towards larger radii and
one of the spirals crosses the south dust clump. Finally, we present different
scenarios in order to explain the complex structure of the disk.Comment: 15 pages, 11 figures. The paper has been published in ApJ. References
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Assessing the spin-orbit obliquity of low-mass planets in the breaking the chain formation model: A story of misalignment
The spin-orbit obliquity of a planetary system constraints its formation
history. A large obliquity may either indicate a primordial misalignment
between the star and its gaseous disk or reflect the effect of different
mechanisms tilting planetary systems after formation. Observations and
statistical analysis suggest that system of planets with sizes between 1 and 4
R have a wide range of obliquities (), and that
single- and multi-planet transiting have statistically indistinguishable
obliquity distributions. Here, we revisit the ``breaking the chains'' formation
model with focus in understanding the origin of spin-orbit obliquities. This
model suggests that super-Earths and mini-Neptunes migrate close to their host
stars via planet-disk gravitational interactions, forming chain of planets
locked in mean-motion resonances. After gas-disk dispersal, about 90-99\% of
these planetary systems experience dynamical instabilities, which spread the
systems out. Using synthetic transit observations, we show that if planets are
born in disks where the disk angular momentum is virtually aligned with the
star's rotation spin, their final obliquity distributions peak at about 5
degrees or less, and the obliquity distributions of single and multi-planet
transiting systems are statistically distinct. By treating the star-disk
alignment as a free-parameter, we show that the obliquity distributions of
single and multi-planet transiting systems only become statistically
indistinguishable if planets are assumed to form in primordially misaligned
natal disks with a ``tilt'' distribution peaking at 10-20 deg. We
discuss the origin of these misalignments in the context of star formation and
potential implications of this scenario for formation models.Comment: 11 pages, 9 figures, 2 tables. Accepted for publication in MNRA
The North Italian innovative project for common psychiatric disorders: Evaluating the output of a treatment model of an outpatient clinic for anxiety and depression
Depressive disorders were considered the first causes of disability worldwide as early as 2018. The outpatient clinic for anxiety and depression at the University Hospital of Varese represents a service that fully responds to the growing number of requests. Approximately 1,350 medical records have been opened from 2010 to December 2021. The most frequent presenting diagnoses included anxiety disorders (36.8%), severe stress and maladaptation syndromes (35.5%), and depressive episodes (18%). The outpatient clinic has proved to be a model with great impact on users offering a range of diagnostic and therapeutic offers responding to the requests of the community
Millimetre spectral indices of transition disks and their relation to the cavity radius
Transition disks are protoplanetary disks with inner depleted dust cavities
and excellent candidates to investigate the dust evolution under the existence
of a pressure bump. A pressure bump at the outer edge of the cavity allows dust
grains from the outer regions to stop their rapid inward migration towards the
star and efficiently grow to millimetre sizes. Dynamical interactions with
planet(s) have been one of the most exciting theories to explain the clearing
of the inner disk. We look for evidence of the presence of millimetre dust
particles in transition disks by measuring their spectral index with new and
available photometric data. We investigate the influence of the size of the
dust depleted cavity on the disk integrated millimetre spectral index. We
present the 3mm photometric observations carried out with PdBI of four
transition disks: LkHa330, UXTauA, LRLL31, and LRLL67. We use available values
of their fluxes at 345GHz to calculate their spectral index, as well as the
spectral index for a sample of twenty transition disks. We compare the
observations with two kind of models. In the first set of models, we consider
coagulation and fragmentation of dust in a disk in which a cavity is formed by
a massive planet located at different positions. The second set of models
assumes disks with truncated inner parts at different radius and with power-law
dust size distributions, where the maximum size of grains is calculated
considering turbulence as the source of destructive collisions. We show that
the integrated spectral index is higher for transition disks than for regular
protoplanetary disks. For transition disks, the probability that the measured
spectral index is positively correlated with the cavity radius is 95%. High
angular resolution imaging of transition disks is needed to distinguish between
the dust trapping scenario and the truncated disk case.Comment: Accepted for publication in A&A, including language editio
miR-SEA: miRNA Seed Extension based Aligner Pipeline for NGS Expression Level Extraction
The advent of Next Generation Sequencing (NGS) technology has enabled a new major approach for micro RNAs (miRNAs) expression profiling through the so called RNA-Sequencing (RNA-Seq). Different tools have been developed in the last years in order to detect and quantify miRNAs, especially in pathological samples, starting from the big amount of data deriving from RNA sequencing. These tools, usually relying on general purpose alignment algorithms, are however characterized by different sensitivity and accuracy levels and in the most of the cases provide not overlapping predictions. To overcome these limitations we propose a novel pipeline for miRNAs detection and quantification in RNA-Seq sample, miRNA Seed Extension Aligner (miR-SEA), based on an experimental evidence concerning miRNAs structure. The proposed pipeline was tested on three Colorectal Cancer (CRC) RNA-Seq samples and the obtained results compared with those provided by two well-known miRNAs detection tools showing good ability in performing detection and quantification more adherent to miRNAs structur
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