528 research outputs found
The circumstellar disc around the Herbig AeBe star HD169142
We present 7 mm and 3.5 cm wavelength continuum observations toward the
Herbig AeBe star HD169142 performed with the Very Large Array (VLA) with an
angular resolution of ~1". We find that this object exhibits strong (~4.4 mJy),
unresolved (~1") 7 mm continuum emission, being one of the brightest isolated
Herbig AeBe stars ever detected with the VLA at this wavelength. No emission is
detected at 3.5 cm continuum, with a 3 sigma upper limit of ~0.08 mJy. From
these values, we obtain a spectral index of ~2.5 in the 3.5 cm to 7 mm
wavelength range, indicating that the observed flux density at 7mm is most
likely dominated by thermal dust emission coming from a circumstellar disc. We
use available photometric data from the literature to model the spectral energy
distribution (SED) of this object from radio to near-ultraviolet frequencies.
The observed SED can be understood in terms of an irradiated accretion disc
with low mass accretion rate, 10^{-8} solar masses per year, surrounding a star
with an age of ~10 Myr. We infer that the mass of the disc is ~0.04 solar
masses, and is populated by dust grains that have grown to a maximum size of 1
mm everywhere, consistent with the lack of silicate emission at 10 microns.
These features, as well as indications of settling in the wall at the dust
destruction radius, led us to speculate the disc of HD169142 is in an advanced
stage of dust evolution, particularly in its inner regions.Comment: 13 pages, 2 figures. Accepted by MNRA
Accounting and Psychiatric Power in Italy: The Royal Insane Hospital of Turin in the 19th Century
This paper identifies the importance of accounting practices in the successful operation of the Royal Insane Hospital of Turin, prior to the Italian unification, to show the importance of the lunatic asylum to our understanding of the way in which power is sustained by the State and the dependence of this process on the information and discourses created by accounting practices. The study is informed by insights from Michel Foucault's work on lunatic asylums and psychiatric power. Accounting practices of the Royal Insane Hospital of Turin allowed the State as a major contributor to the funding of the asylum to control and monitor the cost of providing the necessary facilities and care for patients. Accounting allowed the hospital to be managed more efficiently which, most importantly, allowed the hospital to provide the support and facilities which were essential for creating the environment required for new medical practices in the treatment of the mentally unwell at a time when the role of doctors was becoming increasingly important. Accounting is also shown to have played a prominent role in supporting the political and social legitimation of the institution and its claim for public and private support. Critical to this process was the social and political importance of the statistics produced by the doctors of the lunatic asylum
Unveiling the Structure of Pre-Transitional Disks
In the past few years, several disks with inner holes that are empty of small
dust grains have been detected and are known as transitional disks. Recently,
Spitzer has identified a new class of "pre-transitional disks" with gaps; these
objects have an optically thick inner disk separated from an optically thick
outer disk by an optically thin disk gap. A near-infrared spectrum provided the
first confirmation of a gap in the pre-transitional disk of LkCa 15 by
verifying that the near-infrared excess emission in this object was due to an
optically thick inner disk. Here we investigate the difference between the
nature of the inner regions of transitional and pre-transitional disks using
the same veiling-based technique to extract the near-infrared excess emission
above the stellar photosphere. We show that the near-infrared excess emission
of the previously identified pre-transitional disks of LkCa 15 and UX Tau A in
Taurus as well as the newly identified pre-transitional disk of ROX 44 in
Ophiuchus can be fit with an inner disk wall located at the dust destruction
radius. We also model the broad-band SEDs of these objects, taking into account
the effect of shadowing by the inner disk on the outer disk, considering the
finite size of the star. The near-infrared excess continua of these three
pre-transitional disks, which can be explained by optically thick inner disks,
are significantly different from that of the transitional disks of GM Aur,
whose near-infrared excess continuum can be reproduced by emission from
sub-micron-sized optically thin dust, and DM Tau, whose near-infrared spectrum
is consistent with a disk hole that is relatively free of small dust. The
structure of pre-transitional disks may be a sign of young planets forming in
these disks and future studies of pre-transitional disks will provide
constraints to aid in theoretical modeling of planet formation.Comment: Accepted for publication in ApJ on May 10, 2010; 29 page
Emission from Water Vapor and Absorption from Other Gases at 5-7.5 Microns in Spitzer-IRS Spectra of Protoplanetary Disks
We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming
region showing emission in Spitzer Space Telescope Infrared Spectrograph (IRS)
5-7.5 micron spectra from water vapor and absorption from other gases in these
stars' protoplanetary disks. Seven stars' spectra show an emission feature at
6.6 microns due to the nu_2 = 1-0 bending mode of water vapor, with the shape
of the spectrum suggesting water vapor temperatures > 500 K, though some of
these spectra also show indications of an absorption band, likely from another
molecule. This water vapor emission contrasts with the absorption from warm
water vapor seen in the spectrum of the FU Orionis star V1057 Cyg. The other
six of the thirteen stars have spectra showing a strong absorption band,
peaking in strength at 5.6-5.7 microns, which for some is consistent with
gaseous formaldehyde (H2CO) and for others is consistent with gaseous formic
acid (HCOOH). There are indications that some of these six stars may also have
weak water vapor emission. Modeling of these stars' spectra suggests these
gases are present in the inner few AU of their host disks, consistent with
recent studies of infrared spectra showing gas in protoplanetary disks.Comment: 33 pages, 9 figures, to appear in the 20 August, 2014, V791 - 2 issue
of the Astrophysical Journa
Canine parvovirus and pseudorabies virus coinfection as a cause of death in a wolf (Canis lupus) from southern Italy
Pseudorabies virus (PRV) or suid herpesvirus 1 (SHV-1) is the causative agent of
Aujeszky's disease, a highly contagious viral infection which causes neurological fatal
illness in mammals other than suids. Here we report a case of a young wolf (Canis
lupus) of around 2 years found dead by a hunter in the province of Avellino, Campania
Region. Necropsy showed pathological findings consistent with encephalitis and gastroenteritis.
Organs were analysed by microbiological and molecular investigations
following standard procedures to ascertain the possible cause of death. Real-time
PCR revealed the presence of PRV in the brain and of canine parvovirus 2b in organs
like intestine, liver, brain, kidney and pancreas. Death probably occurred very shortly
after SHV-1 infection in an animal already weakened by parvovirosis
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