Deriving the extinction to young stellar objects using [FeII] near-infrared emission lines. Prescriptions from GIANO high-resolution spectra

The near-infrared emission lines of Fe$^{+}$ at 1.257, 1.321, and 1.644 $\mu$m share the same upper level; their ratios can then be exploited to derive the extinction to a line emitting region once the relevant spontaneous emission coefficients are known. This is commonly done, normally from low-resolution spectra, in observations of shocked gas from jets driven by Young Stellar Objects. In this paper we review this method, provide the relevant equations, and test it by analyzing high-resolution ($R \sim 50000$) near-infrared spectra oftwo young stars, namely the Herbig Be star HD 200775 and the Be star V1478 Cyg, which exhibit intense emission lines. The spectra were obtained with the new GIANO echelle spectrograph at the Telescopio Nazionale Galileo. Notably, the high-resolution spectra allowed checking the effects of overlapping telluric absorption lines. A set of various determinations of the Einstein coefficients are compared to show how much the available computations affect extinction derivation. The most recently obtained values are probably good enough to allow reddening determination within 1 visual mag of accuracy. Furthermore, we show that [FeII] line ratios from low-resolution pure emission-line spectra in general are likely to be in error due to the impossibility to properly account for telluric absorption lines. If low-resolution spectra are used for reddening determinations, we advice that the ratio 1.644/1.257, rather than 1.644/1.321, should be used, being less affected by the effects of telluric absorption lines.Comment: 17 pages, 6 figures, to be published in PAS

Reducing GIANO-B spectra with IRAF. The GIANOTOOLS handbook

GIANO is a near infrared echelle spectrograph operating at Nasmyth focus A of Telescopio Nazionale Galileo. It is a second generation instrument and allows obtaining spectra that cover most of the range 0.9--2.5 mum with a single exposure. The spectral interval is covered through 49 orders and only a few small windows fall outside the detector. GIANO-B is an upgrade of GIANO and has been available since 2017. Unlike GIANO, it is not fibre-fed but light is now transferred to the slit through pre-slit optics. This document is the updated version of the first ``Reducing GIANO Spectra'' handbook and explains how to reduceand extract GIANO-B calibrated spectra by using routines available in any basic installation of IRAF, the Image Reduction and Analysis Facility developed by the NOAO, plus the suite GIANOTOOLS of ad-hoc scripts, the latest version of which can be obtained from the author of this handbook. IRAF is one of the most commonly used scientific suites of software packages for reducing and analysing images and spectra, freely downloadable, and offering many routines which are both fully optimised and tested. Its versatile Command Language also allows scripting and easy customisation

The binary Be star δ\delta Scorpii at high spectral and spatial resolution : II The circumstellar disk evolution after the periastron

Classical Be stars are hot non-supergiant stars surrounded by a gaseous circumstellar disk that is responsible for the observed infrared (IR) excess and emission lines. The influence of binarity on these phenomena remains controversial. We followed the evolution of the environment surrounding the binary Be star $\delta$ Scorpii one year before and one year after the 2011 periastron to check for any evidence of a strong interaction between its companion and the primary circumstellar disk. We used the VLTI/AMBER spectro-interferometric instrument operating in the K band in high (12000) spectral resolution to obtain information on both the disk geometry and kinematics. Observations were carried out in two emission lines: Br$\gamma$ (2.172\,$\mu$m) and \ion{He}{i} (2.056\,$\mu$m). We detected some important changes in $\delta$ Scorpii's circumstellar disk geometry between the first observation made in April 2010 and the new observation made in June 2012. During the last two years the disk has grown at a mean velocity of 0.2\,km\,s$^{-1}$. This is compatible with the expansion velocity previously found during the 2001-2007 period. The disk was also found to be asymmetric at both epochs, but with a different morphology in 2010 and 2012. Considering the available spectroscopic data showing that the main changes in the emission-line profiles occurred quickly during the periastron, it is probable that the differences between the 2010 and 2012 disk geometry seen in our interferometric data stem from a disk perturbation caused by the companion tidal effects. However, taking into account that no significant changes have occurred in the disk since the end of the 2011 observing season, it is difficult to understand how this induced inhomogeneity has been "frozen" in the disk for such a long period.Comment: Astronomy and Astrophysics (2013

Testing circumstellar disk lifetimes in young embedded clusters associated with the Vela Molecular Ridge

Context. The Vela Molecular Ridge hosts a number of young embedded star clusters in the same evolutionary stage. Aims. The main aim of the present work is testing whether the fraction of members with a circumstellar disk in a sample of clusters in the cloud D of the Vela Molecular Ridge, is consistent with relations derived for larger samples of star clusters with an age spread. Besides, we want to constrain the age of the young embedded star clusters associated with cloud D. Methods. We carried out L (3.78 microns) photometry on images of six young embedded star clusters associated with cloud D of the Vela Molecular Ridge, taken with ISAAC at the VLT. These data are complemented with the available HKs photometry. The 6 clusters are roughly of the same size and appear to be in the same evolutionary stage. The fraction of stars with a circumstellar disk was measured in each cluster by counting the fraction of sources displaying a NIR excess in colour-colour (HKsL) diagrams. Results. The L photometry allowed us to identify the NIR counterparts of the IRAS sources associated with the clusters. The fraction of stars with a circumstellar disk appears to be constant within errors for the 6 clusters. There is a hint that this is lower for the most massive stars. The age of the clusters is constrained to ~1-2 Myr. Conclusions. The fraction of stars with a circumstellar disk in the observed sample is consistent with the relations derived from larger samples of star clusters and with other age estimates for cloud D. The fraction may be lower for the most massive stars. Our results agree with a scenario where all intermediate and low-mass stars form with a disk, whose lifetime is shorter for higher mass stars.Comment: 13 pages, 11 figures, accepted for publication in Astronomy and Astrophysic

The BLAST Survey of the Vela Molecular Cloud: Dynamical Properties of the Dense Cores in Vela-D

The Vela-D region, according to the nomenclature given by Murphy & May (1991), of the star forming complex known as the Vela Molecular Ridge (VMR), has been recently analyzed in details by Olmi et al. (2009), who studied the physical properties of 141 pre- and proto-stellar cold dust cores, detected by the ``Balloon-borne Large-Aperture Submillimeter Telescope'' (BLAST) during a much larger (55 sq. degree) Galactic Plane survey encompassing the whole VMR. This survey's primary goal was to identify the coldest, dense dust cores possibly associated with the earliest phases of star formation. In this work, the dynamical state of the Vela-D cores is analyzed. Comparison to dynamical masses of a sub-sample of the Vela-D cores estimated from the 13CO survey of Elia et al. (2007), is complicated by the fact that the 13CO linewidths are likely to trace the lower density intercore material, in addition to the dense gas associated with the compact cores observed by BLAST. In fact, the total internal pressure of these cores, if estimated using the 13CO linewidths, appears to be higher than the cloud ambient pressure. If this were the case, then self-gravity and surface pressure would be insufficient to bind these cores and an additional source of external confinement (e.g., magnetic field pressure) would be required. However, if one attempts to scale down the 13CO linewidths, according to the observations of high-density tracers in a small sample of sources, then most proto-stellar cores would result effectively gravitationally bound.Comment: This paper has 12 pages and 6 figures. Accepted for publication by the Astrophysical Journal on July 19, 201

Protostellar Outflows at the EarliesT Stages (POETS). III. H2O masers tracing disk-winds and jets near luminous YSOs

The goal of the Protostellar Outflows at the EarliesT Stages (POETS) survey is to image the disk-outflow interface on scales of 10-100 au in a statistically significant sample (36) of luminous young stellar objects (YSO), targeting both the molecular and ionized components of the outflows. The outflow kinematics is studied at milliarcsecond scales through VLBI observations of the 22 GHz water masers. We employed the JVLA at 6, 13, and 22 GHz in the A- and B-Array configurations to determine the spatial structure and the spectral index of the radio continuum emission. In about half of the targets, the water masers observed at separation <= 1000 au from the YSOs trace either or both of these kinematic structures: 1) a spatially elongated distribution oriented at close angle with the direction of collimation of the maser proper motions (PM), and 2) a linear LSR velocity (Vlsr) gradient across the YSO position. The kinematic structure (1) is readily interpreted in terms of a protostellar jet, as confirmed in some targets via the comparison with independent observations of the YSO jets, in thermal (continuum and line) emissions, reported in the literature. The kinematic structure (2) is interpreted in terms of a disk-wind (DW) seen almost edge-on on the basis of several pieces of evidence: first, it is invariably directed perpendicular to the YSO jet; second, it agrees in orientation and polarity with the Vlsr gradient in thermal emissions (when reported in the literature) identifying the YSO disk at scales of <= 1000~au; third, the PMs of the masers delineating the Vlsr gradients hint at flow motions at a speed of 10-20 km/s directed at large angles with the disk midplane. In the remaining targets, the maser PMs are not collimated but rather tend to align along two almost perpendicular directions, and could originate in DW-jet systems slightly inclined (<= 30 deg) with respect to edge-on.Comment: 61 pages (Main: 13 pages, Appendix: 48 pages), 18 figures (5 + 13), 28 tables (1 + 27), accepted for publication in section 6. Interstellar and circumstellar matter of A&

The 2008-2009 outburst of the young binary system Z CMa unraveled by interferometry with high spectral resolution

Z CMa is a young binary system consisting of an Herbig primary and a FU Ori companion. Both components seem to be surrounded by active accretion disks and a jet was associated to the Herbig B0. In Nov. 2008, K. Grankin discovered that Z CMa was exhibiting an outburst with an amplitude larger than any photometric variations recorded in the last 25 years. To study the innermost regions in which the outburst occurs and understand its origin, we have observed both binary components with AMBER/VLTI across the Br{\gamma} emission line in Dec. 2009 in medium and high spectral resolution modes. Our observations show that the Herbig Be, responsible for the increase of luminosity, also produces a strong Br{\gamma} emission, and they allow us to disentangle from various origins by locating the emission at each velocities through the line. Considering a model of a Keplerian disk alone fails at reproducing the asymmetric spectro-astrometric measurements, suggesting a major contribution from an outflow.Comment: To be published in the proceedings of the SPIE'2010 conference on "Optical and Infrared Interferometry II

Triggered massive-star formation on the borders of Galactic HII regions Evidence for the collect and collapse process around RCW 79

We present SEST-SIMBA 1.2-mm continuum maps and ESO-NTT SOFI JHK images of the Galactic HII region RCW 79. The millimetre continuum data reveal the presence of massive fragments located in a dust emission ring surrounding the ionized gas. The two most massive fragments are diametrically opposite each other in the ring. The near-IR data, centred on the compact HII region located at the south-eastern border of RCW 79, show the presence of an IR-bright cluster containing massive stars along with young stellar objects with near-IR excesses. A bright near- and mid-IR source is detected towards maser emissions, 1.2 pc north-east of the compact HII region centre. Additional information, extracted from the Spitzer GLIMPSE survey, are used to discuss the nature of the bright IR sources observed towards RCW 79. Twelve luminous Class I sources are identified towards the most massive millimetre fragments. All these facts strongly indicate that the massive-star formation observed at the border of the HII region RCW 79 has been triggered by its expansion, most probably by the collect and collapse process

Young open clusters in the galactic star forming region NGC 6357

NGC6357 is an active star forming region with very young massive open clusters (OC). These clusters contain some of the most massive stars in the Galaxy and strongly interact with nearby giant molecular clouds (GMC). We study the young stellar populations of the region and of the OC Pismis24, focusing on their relationship with the nearby GMCs. We seek evidence of triggered star formation propagating from the clusters. We used new deep JHKs photometry, along with unpublished deep IRAC/Spitzer MIR photometry, complemented with optical HST/WFPC2 high spatial resolution photometry and X-ray Chandra observations, to constrain age, initial mass function, and star formation modes in progress. We carefully examine and discuss all sources of bias (saturation, confusion, different sensitivities, extinction). NGC6357 hosts three large young stellar clusters, of which Pismis24 is the most prominent. We found that Pismis24 is a very young (~1-3 Myr) OC with a Salpeter-like IMF and a few thousand members. A comparison between optical and IR photometry indicates that the fraction of members with a NIR excess (i. e., with a circumstellar disk) is in the range 0.3-0.6, consistent with its photometrically derived age. We also find that Pismis24 is likely subdivided into a few different sub-clusters, one of which contains almost all the massive members. There are indications of current star formation triggered by these massive stars, but clear age trends could not be derived (although the fraction of stars with a NIR excess does increase towards the HII region associated with the cluster). The gas out of which Pismis24 formed must have been distributed in dense clumps within a cloud of less dense gas ~1 pc in radius. Our findings provide some new insight into how young stellar populations and massive stars emerge, and evolve in the first few Myr after birth, from a giant molecular cloud complex.Comment: 34 pages, 26 figures, to be published in Astronomy & Astrophysic

some pathogenic characters of paratyphoid salmonella enterica strains isolated from poultry

Abstract Objective To investigate some pathogenic characters of Salmonella enterica strains isolated from poultry. Methods Twenty-three genetically distinct Salmonella enterica strains, of different serovars and pulsotype, were examined for virulence traits. Resistance to gastric acid environment was estimated by measuring the percentage of survived bacterial cells after exposure for 2 h to a synthetic gastric juice. Strains were analyzed with PCR for the presence of the following virulence genes: mgtC and rhuM located on SPI-3, sopB and pipB located on SPI-5, Salmonella virulence plasmid (spv) R (spvR), spvB and spvC located on Salmonella plasmid virulence and sodCI, sopE, and gipA located on prophage. Finally, resistance to 21 antibiotics was tested with Kirby–Bauer method. Results A percentage of 82.60% of strains were resistant to gastric environment after induction and 60.87% of the strains exhibited constitutive resistance too. Nineteen different virulence profiles were detected. The phage related genes sodCI and sopE and the plasmid mediated operon spvR, spvB and spvC (spvRBC) were detected in 82.60%, 47.82% and 52.17% of strains, respectively. Typhimurium and Enteritidis strains showed the highest number of virulence genes. Twenty-one different antibiotic resistance profiles were obtained and two isolates (Typhimurium and Enteritidis) resulted sensible to all the tested molecules. The ampicillin, streptomycin, sulfonamide and tetracycline resistance profile was detected in seven isolates (30.43%). Conclusion Our results show that paratyphoid Salmonella strains with several characters of pathogenicity, that may be cause of severe pathology in animals and humans, are circulating among poultry