Optical properties of carbon grains: Influence on dynamical models of AGB stars

For amorphous carbon several laboratory extinction data are available, which show quite a wide range of differences due to the structural complexity of this material. We have calculated self-consistent dynamic models of circumstellar dust-shells around carbon-rich asymptotic giant branch stars, based on a number of these data sets. The structure and the wind properties of the dynamical models are directly influenced by the different types of amorphous carbon. In our test models the mass loss is not severely dependent on the difference in the optical properties of the dust, but the influence on the degree of condensation and the final outflow velocity is considerable. Furthermore, the spectral energy distributions and colours resulting from the different data show a much wider spread than the variations within the models due to the variability of the star. Silicon carbide was also considered in the radiative transfer calculations to test its influence on the spectral energy distribution.Comment: 12 pages, 6 figures. To appear in A&

The kinematics of molecular clumps surrounding hot cores in G29.96-0.02 and G31.41+0.31

We present high angular resolution interferometric observations of the 3 and 1.3mm continuum emission, and HCO+(1-0) and SiO(2-1)v=0 lines, obtained with the Owens Valley Radio Observatory millimeter-wave array, toward two hot cores (HCs) associated with two well known ultracompact (UC) HII regions: G29.96-0.02 and G31.41+0.31. These HCs are believed to host young forming massive stars which have been suggested to be surrounded by massive rotating accretion disks. The aim of these new observations is to study the structure and kinematics of the molecular clumps surrounding the HCs and nearby UCHII regions at moderately high angular resolution. Our observations reveal that the clumps within which the HCs and UCHII regions are embedded have a complex kinematical structure. The total mass of the clumps is estimated to be in the range 1000-3000 Msun, consistent with previous findings. Our observations also show compelling evidence that the clump in G29.96-0.02 is contracting onto the HC position, suggesting that the accretion process onto the massive young stellar object embedded in the HC is still ongoing. In these objects the kinematical structure that we observe is also compatible with the presence of a massive rotating disk within the HC, even though we cannot prove this suggestion with our data. The case of G31.41+0.31 is more complicated, and our data, although consistent with the presence of an inner disk and an infalling envelope around it, do not have the required spatial resolution to resolve the different structures.Comment: 13 pages, 15 figs, A&A in pres

X-Ray Emission from Young Stars in the Massive Star Forming Region IRAS 20126+4104

We present a $40\,$ks Chandra observation of the IRAS$\,$20126+4104 core region. In the inner $6^{\prime\prime}$ two X-ray sources were detected, which are coincident with the radio jet source I20S and the variable radio source I20Var. No X-ray emission was detected from the nearby massive protostar I20N. The spectra of both detected sources are hard and highly absorbed, with no emission below $3\,$keV. For I20S, the measured $0.5-8\,$keV count rate was $4.3\,$cts$\,$ks$^{-1}$. The X-ray spectrum was fit with an absorbed 1T APEC model with an energy of kT$\,=10\,$keV and an absorbing column of N$_H = 1.2\times 10^{23}\,$cm$^{-2}$. An unabsorbed X-ray luminosity of about $1.4\times 10^{32}\,$erg$\,$s$^{-1}$ was estimated. The spectrum shows broad line emission between 6.4 and 6.7\, keV, indicative of emission from both neutral and highly ionized iron. The X-ray lightcurve indicates that I20S is marginally variable; however, no flare emission was observed. The variable radio source I20Var was detected with a count rate of $0.9\,$cts$\,$ks$^{-1}$ but there was no evidence of X-ray variability. The best fit spectral model is a 1T APEC model with an absorbing hydrogen column of N$_H = 1.1\times 10^{23}\,$cm$^{-2}$ and a plasma energy of kT = 6.0$\,$keV. The unabsorbed X-ray luminosity is about $3\times 10^{31}\,$erg$\,$s$^{-1}$.Comment: 17pages, 4 figures to appear in Astronomical Journa

High Resolution Observations of the Massive Protostar in IRAS18566+0408

We report 3 mm continuum, CH3CN(5-4) and 13CS(2-1) line observations with CARMA, in conjunction with 6 and 1.3 cm continuum VLA data, and 12 and 25 micron broadband data from the Subaru Telescope toward the massive proto-star IRAS18566+0408. The VLA data resolve the ionized jet into 4 components aligned in the E-W direction. Radio components A, C, and D have flat cm SEDs indicative of optically thin emission from ionized gas, and component B has a spectral index alpha = 1.0, and a decreasing size with frequency proportional to frequency to the -0.5 power. Emission from the CARMA 3 mm continuum, and from the 13CS(2-1), and CH3CN(5-4) spectral lines is compact (i.e. < 6700 AU), and peaks near the position of VLA cm source, component B. Analysis of these lines indicates hot, and dense molecular gas, typical for HMCs. Our Subaru telescope observations detect a single compact source, coincident with radio component B, demonstrating that most of the energy in IRAS18566+0408 originates from a region of size < 2400 AU. We also present UKIRT near-infrared archival data for IRAS18566+0408 which show extended K-band emission along the jet direction. We detect an E-W velocity shift of about 10 km/sec over the HMC in the CH3CN lines possibly tracing the interface of the ionized jet with the surrounding core gas. Our data demonstrate the presence of an ionized jet at the base of the molecular outflow, and support the hypothesis that massive protostars with O-type luminosity form with a mechanism similar to lower mass stars

Carbon recombination lines in the Orion Bar

We have carried out VLA D-array observations of the C91alpha carbon recombination line as well as Effelsberg 100-m observations of the C65alpha line in a 5 arcmin square region centered between the Bar and the Trapezium stars in the Orion Nebula with spatial resolutions of 10 arcsec and 40 arcsec, respectively. The results show the ionized carbon in the PDR associated with the Orion Bar to be in a thin, clumpy layer sandwiched between the ionization front and the molecular gas. From the observed line widths we get an upper limit on the temperature in the C+ layer of 1500 K and from the line intensity a hydrogen density between 5 10^4 and 2.5 10^5 cm-3 for a homogeneous medium. The observed carbon level population is not consistent with predictions of hydrogenic recombination theory but could be explained by dielectronic recombination. The layer of ionized carbon seen in C91alpha is found to be essentially coincident with emission in the v=1-0 S(1) line of vibrationally excited molecular hydrogen. This is surprising in the light of current PDR models and some possible explanations of the discrepancy are discussed.Comment: 9 pages, 3 Postscript figures, uses aaspp4 and psfig, To Appear in ApJ Letters (accepted Jul. 24, 1997

10 ans de lutte contre la violence domestique dans le canton de Vaud: résumé de la recherche menée par l'Unité de Médecine des Violences (UMV) sur mandat de la Commission cantonale de lutte contre la violence domestique (CCLVD)

[Sommaire] Introduction. - 1. Quelques données de base: le contexte juridique, la violence domestique: une réalité chiffrée, principales institutions du réseau d'aide dans le canton de Vaud. - 2. Résumé de la recherche "10 ans de lutte contre la violence domestique dans le canton de Vaud": contexte, méthode, résultats, recommandations à l'intention de la CCLVD. - 3. Axes stratégiques de la politique cantonale de prévention de lutte contre la violence domestique 2011-2015. - Bibliographie [Introduction (extrait)] La violence entre membres d'une même famille ou entre proches, à savoir la violence domestique, a longtemps été considérée comme une affaire privée et un tabou. Un important changement de mentalité s'est toutefois opéré ces 20 dernières années. La lutte contre la violence envers les femmes d'une manière générale et contre la violence domestique en particulier préoccupe de plus en plus les organes internationaux, nationaux et locaux et est reconnue comme une tâche d'intérêt public. [...] Dans le canton de Vaud, en 1999, le Bureau de l'égalité entre les femmes et les hommes (BEFH) a mandaté l'Unité de Prévention de l'Institut de médecine sociale et préventive du CHUV, afin de mener une étude sur la violence conjugale, auprès des institutions concernées2. Cette recherche visait à établir un état des lieux et à identifier les besoins prioritaires. En 2001, des recommandations ont émergé de cette étude sous la forme de 40 mesures. Six d'entre elles ont été retenues comme prioritaires par la Conseillère d'Etat Madame Jacqueline Maurer Mayor. Presque 10 ans après, en automne 2008, la Commission cantonale de lutte contre la violence domestique (CCLVD), instituée par le Conseil d'Etat afin de coordonner les efforts en vue de la prévention et de la lutte contre la violence domestique, a décidé de faire un bilan sur la réalisation de ces mesures, d'identifier les besoins actuels des professionnel-le-s de terrain et les problématiques émergeantes. Les résultats de cette étude, menée par L'Unité d médecine des violences (UMV) ont servi de fondement à la CCLVD dans l'établissement d'un plan stratégique 2011-2015, en matière de lutte contre la violence conjugale dans le canton de Vaud. Le présent document présente à la fois un éclairage contextuel sur la situation dans le canton de Vaud aujourd'hui et une synthèse de la recherche précitée

First Detection of an H2CO 6 cm Maser Flare: A Burst in IRAS 18566+0408

We report the discovery of a short-duration (less than 3 months) outburst of the H2CO 6 cm maser in IRAS 18566+0408 (G37.55+0.20). During the flare, the peak flux density of the maser increased by a factor of 4; after less than a month, it decayed to the preflare value. This is the first detection of a short, burstlike variability of an H2CO 6 cm maser. The maser shows an asymmetric line profile that is consistent with the superposition of two Gaussian components. We did not detect a change in the velocity or the line width of the Gaussian components during the flare. If the two Gaussian components trace two separate maser regions, then very likely an event outside the maser gas triggered simultaneous flares at two different locations

Mira's wind explored in scattering infrared CO lines

We have observed the intermediate regions of the circumstellar envelope of Mira (o Ceti) in photospheric light scattered by three vibration-rotation transitions of the fundamental band of CO, from low-excited rotational levels of the ground vibrational state, at an angular distance of beta = 2"-7" away from the star. The data were obtained with the Phoenix spectrometer mounted on the 4 m Mayall telescope at Kitt Peak. The spatial resolution is approximately 0.5" and seeing limited. Our observations provide absolute fluxes, leading to an independent new estimate of the mass-loss rate of approximately 3e-7 Msun/yr, as derived from a simple analytic wind model. We find that the scattered intensity from the wind of Mira for 2" < beta < 7" decreases as beta^-3, which suggests a time constant mass-loss rate, when averaged over 100 years, over the past 1200 years.Comment: accepted for publication in the Astrophysical Journa