601 research outputs found
The Life Cycle of Dust
Dust offers a unique probe of the interstellar medium (ISM) across multiple size, density, and temperature scales. Dust is detected in outflows of evolved stars, star-forming molecular clouds, planet-forming disks, and even in galaxies at the dawn of the Universe. These grains also have a profound effect on various astrophysical phenomena from thermal balance and extinction in galaxies to the building blocks for planets, and changes in dust grain properties will affect all of these phenomena. A full understanding of dust in all of its forms and stages requires a multi-disciplinary investigation of the dust life cycle. Such an investigation can be achieved with a statistical study of dust properties across stellar evolution, star and planet formation, and redshift. Current and future instrumentation will enable this investigation through fast and sensitive observations in dust continuum, polarization, and spectroscopy from near-infrared to millimeter wavelengths
OC030: Three‐dimensional ultrasound enhances the identification of vermian fissures in the normal and abnormal cerebellum
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Recurrent Non-Hodgkin’s lymphoma in the uterine cervix: a case report and a review of the literature
Background. Lymphomas are a heterogeneous group of malignant lymphoproliferative diseases. As primary localization, the most common histological subtype of female genital lymphomas is a Non-Hodgkin Lymphoma (NHL), the diffuse large B-cell type. However cervical relapse of NHL is a very rare condition (0.3%). Case presentation. A 42-year-old Peruvian woman experienced relapse of NHL with uterine localization. She complained at first of abnormal vaginal bleeding and stranguria. The cervical biopsy performed showed a diffuse large B-cell lymphoma in the uterine cervix. The lack of clinical studies on this topic and its rarity make this type of recurrence very difficult to treat. Conclusions. In case of a woman with vaginal bleeding and history of NHL, a disease relapse should always be considered, and a biopsy should be performed to confirm the diagnosis. © 2023, EDRA S.p.A. All rights reserved
Volume-limited sample of low-mass red giant stars, the progenitors of hot subdwarf stars I. Sample selection and binary classification method
The current theory predicts that hot subdwarf binaries are produced from
evolved low-mass binaries that have undergone mass transfer and drastic mass
loss during either a common envelope phase or a stable Roche lobe overflow
while on the red giant branch (RGB). We perform a spectroscopic survey to find
binary systems that include low-mass red giants near the tip of the RGB, which
are predicted to be the direct progenitors of subdwarf B (sdB) stars. We aim to
obtain a homogeneous sample to search for the observational evidence of
correlations between the key parameters governing the formation of sdB stars
and constrain the physics of stable mass transfer. In this work, we
concentrated on the southern hemisphere targets and conducted a spectroscopic
survey of 88 red giant stars to search for the long-period RGB + MS binary
systems within 200\,pc. Combining radial velocity (RV) measurements from
ground-based observations with CORALIE and RV measurements from DR2 and
early data release 3 (eDR3) as well as the astrometric excess noise and RUWE
measurements from DR3, we defined a robust binary classification method.
In addition, we searched for known binary systems in the literature and in the
DR3. We select a total of 211 RGB candidates in the southern hemisphere
within 200\,pc based on the DR2 color-magnitude diagram. Among them, a
total of 33 red giants were reported as binary systems with orbital periods
between 100 and 900 days, some of which are expected to be the direct
progenitors of wide binary sdB stars. In addition, we classified 37 new
MS\,+\,RGB binary candidates, whose orbital parameters will be measured with
future spectroscopic follow-up.Comment: 9 pages, 2 figures, accepted for publication in A&
Photoionized gas in hydrostatic equilibrium: the role of gravity
We present a method to include the effects of gravity in the plasma physics
code Cloudy. More precisely, a term is added to the desired gas pressure in
order to enforce hydrostatic equilibrium, accounting for both the self-gravity
of the gas and the presence of an optional external potential. As a test case,
a plane-parallel model of the vertical structure of the Milky Way disk near the
solar neighbourhood is considered. It is shown that the gravitational force
determines the scale height of the disk, and it plays a critical role in
setting its overall chemical composition. However, other variables, such as the
shape of incident continuum and the intensity of the Galactic magnetic field,
strongly affect the predicted structure.Comment: 9 pages, 8 figures, MNRAS in pres
Unexpectedly large mass loss during the thermal pulse cycle of the red giant R Sculptoris!
The asymptotic giant branch star R Sculptoris is surrounded by a detached
shell of dust and gas. The shell originates from a thermal pulse during which
the star undergoes a brief period of increased mass loss. It has hitherto been
impossible to constrain observationally the timescales and mass-loss properties
during and after a thermal pulse - parameters that determine the lifetime on
the asymptotic giant branch and the amount of elements returned by the star.
Here we report observations of CO emission from the circumstellar envelope and
shell around R Sculptoris with an angular resolution of 1.3 arcsec. What was
hitherto thought to be only a thin, spherical shell with a clumpy structure, is
revealed to contain a spiral structure. Spiral structures associated with
circumstellar envelopes have been seen previously, from which it was concluded
that the systems must be binaries. Using the data, combined with hydrodynamic
simulations, we conclude that R Sculptoris is a binary system that underwent a
thermal pulse approximately 1800 years ago, lasting approximately 200 years.
About 0.003 Msun of mass was ejected at a velocity of 14.3 km s-1 and at a rate
approximately 30 times higher than the prepulse mass-loss rate. This shows that
approximately 3 times more mass is returned to the interstellar medium during
and immediately after a pulse than previously thought.Comment: Accepted by Natur
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