764 research outputs found
A Catalog of MIPSGAL Disk and Ring Sources
We present a catalog of 416 extended, resolved, disk- and ring-like objects
as detected in the MIPSGAL 24 micron survey of the Galactic plane. This catalog
is the result of a search in the MIPSGAL image data for generally circularly
symmetric, extended "bubbles" without prior knowledge or expectation of their
physical nature. Most of the objects have no extended counterpart at 8 or 70
micron, with less than 20% detections at each wavelength. For the 54 objects
with central point sources, the sources are nearly always seen in all IRAC
bands. About 70 objects (16%) have been previously identified, with another 35
listed as IRAS sources. Among the identified objects, those with central
sources are mostly listed as emission-line stars, but with other source types
including supernova remnants, luminous blue variables, and planetary nebulae.
The 57 identified objects (of 362) without central sources are nearly all PNe
(~90%).which suggests that a large fraction of the 300+ unidentified objects in
this category are also PNe. These identifications suggest that this is
primarily a catalog of evolved stars. Also included in the catalog are two
filamentary objects that are almost certainly SNRs, and ten unusual compact
extended objects discovered in the search. Two of these show remarkable spiral
structure at both 8 and 24 micron. These are likely background galaxies
previously hidden by the intervening Galactic plane
New radio observations of anomalous microwave emission in the HII region RCW175
We have observed the HII region RCW175 with the 64m Parkes telescope at
8.4GHz and 13.5GHz in total intensity, and at 21.5GHz in both total intensity
and polarization. High angular resolution, high sensitivity, and polarization
capability enable us to perform a detailed study of the different constituents
of the HII region. For the first time, we resolve three distinct regions at
microwave frequencies, two of which are part of the same annular diffuse
structure. Our observations enable us to confirm the presence of anomalous
microwave emission (AME) from RCW175. Fitting the integrated flux density
across the entire region with the currently available spinning dust models,
using physically motivated assumptions, indicates the presence of at least two
spinning dust components: a warm component with a relatively large hydrogen
number density n_H=26.3/cm^3 and a cold component with a hydrogen number
density of n_H=150/cm^3. The present study is an example highlighting the
potential of using high angular-resolution microwave data to break model
parameter degeneracies. Thanks to our spectral coverage and angular resolution,
we have been able to derive one of the first AME maps, at 13.5GHz, showing
clear evidence that the bulk of the AME arises in particular from one of the
source components, with some additional contribution from the diffuse
structure. A cross-correlation analysis with thermal dust emission has shown a
high degree of correlation with one of the regions within RCW175. In the center
of RCW175, we find an average polarized emission at 21.5GHz of
2.2\pm0.2(rand.)\pm0.3(sys.)% of the total emission, where we have included
both systematic and statistical uncertainties at 68% CL. This polarized
emission could be due to sub-dominant synchrotron emission from the region and
is thus consistent with very faint or non-polarized emission associated with
AME.Comment: Accepted for publication in the Astrophysical Journa
Expression analysis of HLA-E and NKG2A and NKG2C receptors points at a role for natural killer function in ankylosing spondylitis
Background. Ankylosing Spondylitis (AS) is a complex chronic inflammatory disease strongly associated with the majority of HLA-B27 alleles. HLA-E are non-classical MHC class I molecules that specifically interact with the natural killer receptors NKG2A (inhibitory) and NKG2C (activating), and have been recently proposed to be involved in AS pathogenesis. Objectives: To analyze the expression of HLA-E and the CD94/NKG2 pair of receptors in HLA-B27 positive AS patients and healthy controls (HC) bearing the AS-associated, B*2705 and the non-AS-associated, B*2709 allele. Methods: The level of surface expression of HLA-E molecules on CD14 positive peripheral blood mononuclear cell was evaluated in 21 HLA-B*2705 patients with AS, 12 HLA-B*2705 HC, 12 HLA-B*2709 HC and 6 HLA-B27 negative HC, using the monoclonal antibody MEM-E/08 by quantitative cytofluorimetric analysis. The percentage and density of expression of HLA-E ligands NKG2A and NKG2C were also measured on CD3-CD56+ NK cells. Results. HLA-E expression in CD14 positive cells was significantly higher in AS patients (587.0 IQR 424-830) compared to B*2705 HC (389 IQR 251.3-440.5, p=0.0007), B*2709 HC (294.5 IQR 209.5-422, p=0.0004) and HLA-B27 negative HC (380 IQR 197.3-515.0, p=0.01). A higher number of NK cells expressing NKG2A compared to NKG2C was found in all cohort analysed as well as a higher cell surface density. Conclusion: The higher surface level of HLA-E molecules in AS patients compared to HC, concurrently with a prevalent expression of NKG2A, suggests that the crosstalk between these two molecules might play a role in AS pathogenesis accounting for the previously reported association between HLA-E and AS
The Luminous Blue Variable RMC127 as seen with ALMA and ATCA
We present ALMA and ATCA observations of the luminous blue variable \rmc. The
radio maps show for the first time the core of the nebula and evidence that the
nebula is strongly asymmetric with a Z-pattern shape. Hints of this morphology
are also visible in the archival \emph{HST} image, which overall
resembles the radio emission. The emission mechanism in the outer nebula is
optically thin free-free in the radio. At high frequencies, a component of
point-source emission appears at the position of the star, up to the ALMA
frequencies. The rising flux density distribution () of this object suggests thermal emission from the ionized
stellar wind and indicates a departure from spherical symmetry with
. We examine different scenarios to explain this excess
of thermal emission from the wind and show that this can arise from a bipolar
outflow, supporting the suggestion by other authors that the stellar wind of
\rmc is aspherical. We fit the data with two collimated ionized wind models and
we find that the mass-loss rate can be a factor of two or more smaller than in
the spherical case. We also fit the photometry obtained by IR space telescopes
and deduce that the mid- to far-IR emission must arise from extended, cool
() dust within the outer ionized nebula. Finally we discuss two
possible scenarios for the nebular morphology: the canonical single star
expanding shell geometry, and a precessing jet model assuming presence of a
companion star.Comment: Accepted for publication in ApJ (minor revision included
AMBER/VLTI observations of 5 giant stars
While the search for exoplanets around main sequence stars more massive than
the Sun have found relatively few such objects, surveys performed around giant
stars have led to the discovery of more than 30 new exoplanets. The interest in
studying planet hosting giant stars resides in the possibility of investigating
planet formation around stars more massive than the Sun. Masses of isolated
giant stars up to now were only estimated from evolutionary tracks, which led
to different results depending on the physics considered. To calibrate the
theory, it is therefore important to measure a large number of giant star
diameters and masses as much as possible independent of physical models. We aim
in the determination of diameters and effective temperatures of 5 giant stars,
one of which is known to host a planet. AMBER/VLTI observations with the ATs
were executed in low resolution mode on 5 giant stars. In order to measure high
accurate calibrated squared visibilities, a calibrator-star-calibrator
observational sequence was performed. We measured the uniform disk and
limb-darkened angular diameters of 4 giant stars. The effective temperatures
were also derived by combining the bolometric luminosities and the
interferometric diameters. Lower effective temperatures were found when
compared to spectroscopic measurements. The giant star HD12438 was found to
have an unknown companion star at an angular separation of ~ 12 mas. Radial
velocity measurements present in the literature confirm the presence of a
companion with a very long orbital period (P ~ 11.4 years).}Comment: accepted for publication in A&
The VLTI/MIDI view on the inner mass loss of evolved stars from the Herschel MESS sample
The mass-loss process from evolved stars is a key ingredient for our
understanding of many fields of astrophysics, including stellar evolution and
the chemical enrichment of the interstellar medium via stellar yields. One the
main unsolved questions is the geometry of the mass-loss process. Taking
advantage of the results from the Herschel Mass loss of Evolved StarS (MESS)
programme, we initiated a coordinated effort to characterise the geometry of
mass loss from evolved red giants at various spatial scales. For this purpose
we used the MID-infrared interferometric Instrument (MIDI) to resolve the inner
envelope of 14 asymptotic giant branch stars (AGBs) in the MESS sample. In this
contribution we present an overview of the interferometric data collected
within the frame of our Large Programme, and we also add archive data for
completeness. We studied the geometry of the inner atmosphere by comparing the
observations with predictions from different geometric models. Asymmetries are
detected for five O-rich and S-type, suggesting that asymmetries in the N band
are more common among stars with such chemistry. We speculate that this fact is
related to the characteristics of the dust grains. Except for one star, no
interferometric variability is detected, i.e. the changes in size of the shells
of non-mira stars correspond to changes of the visibility of less than 10%. The
observed spectral variability confirms previous findings from the literature.
The detection of dust in our sample follows the location of the AGBs in the
IRAS colour-colour diagram: more dust is detected around oxygen-rich stars in
region II and in the carbon stars in region VII. The SiC dust feature does not
appear in the visibility spectrum of UAnt and SSct, which are two carbon stars
with detached shells. This finding has implications for the theory of SiC dust
formation.Comment: 43 pages, 31 figures; accepted for publication in Astronomy &
Astrophysics. Abstract shortened for compilation reasons. Metadata correcte
Discovery of Highly Obscured Galaxies in the Zone of Avoidance
We report the discovery of twenty-five previously unknown galaxies in the
Zone of Avoidance. Our systematic search for extended extra-galactic sources in
the GLIMPSE and MIPSGAL mid-infrared surveys of the Galactic plane has revealed
two overdensities of these sources, located around l ~ 47 and 55 degrees and
|b| less than 1 degree in the Sagitta-Aquila region. These overdensities are
consistent with the local large-scale structure found at similar Galactic
longitude and extending from |b| ~ 4 to 40 degrees. We show that the infrared
spectral energy distribution of these sources is indeed consistent with those
of normal galaxies. Photometric estimates of their redshift indicate that the
majority of these galaxies are found in the redshift range z = 0.01 - 0.05,
with one source located at z = 0.07. Comparison with known sources in the local
Universe reveals that these galaxies are located at similar overdensities in
redshift space. These new galaxies are the first evidence of a bridge linking
the large-scale structure between both sides of the Galactic plane at very low
Galactic latitude and clearly demonstrate the feasibility of detecting galaxies
in the Zone of Avoidance using mid-to-far infrared surveys.Comment: Accepted for publication in the Astronomical Journal, 28 pages, 5
tables, 11 figure
Fournier's gangrene and intravenous drug abuse. An unusual case report and review of the literature
Fournier's gangrene is a potentially fatal emergency condition characterized by necrotizing fasciitis and supported by an infection of the external genital, perineal and perianal region, with a rapid and progressive spread from subcutaneous fat tissue to fascial planes.In this case report, a 52-year-old man, with a history of hepatitis C-virus (HCV)-related chronic liver disease and cocaine use disorder for which he was receiving methadone maintenance therapy, was admitted to the Emergency Department with necrotic tissue involving the external genitalia.Fournier's gangrene is usually due to compromised host immunity, without a precise cause of bacterial infection; here it is linked to a loco-regional intravenous injection of cocaine. A multimodal approach, including a wide surgical debridement and a postponed skin graft, was needed. Here we report this case, with a narrative review of the literature
The wonderful complexity of the Mira AB system
We have mapped the CO(3-2) line emission around the Mira AB system at 0.5
resolution using the Atacama Large Millimeter/submillimeter Array (ALMA). The
CO map shows amazing complexity. The circumstellar gas has been shaped by
different dynamical actors during the evolution of the system and several
morphological components can be identified. The companion is marginally
resolved in continuum emission and is currently at 0.4870.006 separation.
In the main line component, centered on the stellar velocity, spiral arcs
around Mira A are found. The spiral appears to be relatively flat and oriented
in the orbital plane. An accretion wake behind the companion is clearly visible
and the projected arc separation is of order 5''. In the blue wing of the line
emission, offset from the main line, several large (5-10''), opposing
arcs are found. We tentatively suggest that this structure is created by the
wind of Mira B blowing a bubble in the expanding envelope of Mira A.Comment: Letter accepted in A&
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