studies in the genus paspalum paniceae poaceae in europe 3 paspalum thunbergii a new naturalized neophyte in w europe

Abstract: Paspalum thunbergii, a weedy species native to E Asia, is reported for the first time from W Europe. In Italy a naturalized population was detected in 2014 in a heathland in Boscaccio (Lentate sul Seveso; Monza and Brianza province, Lombardia region). A subsequent revision of local herbaria revealed the existence of a second population, also in Lombardia, discovered in Mortara (Pavia province) in 2011 and now confirmed. The taxonomy and nomenclature of this species are briefly discussed, as are its ecology and habitat preferences. An original line drawing and photographs of the species and its habitat are provided. An updated identification key for the species of Paspalum in Europe is also presented. Citation: Verloove F., Brusa G. & Ardenghi N. M. G. 2016: Studies in the genus Paspalum (Paniceae, Poaceae) in Europe: 3. Paspalum thunbergii, a new naturalized neophyte in W Europe. — Willdenowia 46: 137–143. doi: http://dx.doi.org/10.3372/wi.46.46111 Version of record first published online on 1 A..

Resolved Mid-Infrared Emission Around AB Aur and V892 Tau with Adaptive Optics Nulling Interferometric Observations

We present the results of adaptive optics nulling interferometric observations of two Herbig Ae stars, AB Aur and V892 Tau. Our observations at 10.3 microns show resolved circumstellar emission from both sources. Further analysis of the AB Aur emission suggests that there is an inclined disk surrounding the star. The diameter of the disk is derived to be 24 to 30 AU with an inclination of 45 to 65 degrees from face-on, and a major-axis PA of 30 +/- 15 degrees (E of N). Differences in the physical characteristics between the mid-IR emission and emission at other wavelengths (near-IR and millimeter), found in previous studies, suggest a complex structure for AB Aur's circumstellar environment, which may not be explained by a disk alone. The similarity in the observed size of AB Aur's resolved emission and that of another Herbig Ae star, HD 100546, is likely coincidental, as their respective evolutionary states and spectral energy distributions suggest significantly different circumstellar environments.Comment: 11 pages, 1 figure, Accepted for publication in ApJ Letter

[Wetlands in the Continental biogeographical region of Northern Italy: from scenarios of change to conservation perspectives]

[Wetlands are extremely important ecosystems for supporting biodiversity and providing services. Nonetheless, although they are mostly protected through several regulations, wetlands are affected by many negative factors that are leading to progressive deterioration of their conservation status. This circumstance is especially obvious in the Continental biogeographical region of Northern Italy, which is included in Piedmont and Lombardy on the left hydrographic side of the River Po. The goal of this study was to assess the main ecological drivers, i.e. the most important ecological factors, including pressures and threats, that shape negatively ecosystem dynamics, hence affecting conservation targets, and finally to suggest actions for counteracting them. Analyses were done at different scales, through bibliographic researches and site-specific data processing. As a result, we identified groups of ecological drivers, among which three were recognized as prevalent: a) the anthropic alteration of water levels; and b) the natural ecological succession in combination to c) the abandonment of traditional land use practices. The last two main ecological drivers were regarded as those to be counteracted by removing biomass (through digging, mowing, fire), because they may produce cascading effects and work against all the other ecological drivers. However, it is necessary to define a new reference framework based on pointing out conservation priorities at large scale (regional or supra-regional) and conservation actions at local scale, both focused on adaptive management.] [Article in Italian

Large Binocular Telescope Adaptive Optics System: New achievements and perspectives in adaptive optics

The Large Binocular Telescope (LBT) is a unique telescope featuring two co-mounted optical trains with 8.4m primary mirrors. The telescope Adaptive Optics (AO) system uses two innovative key components, namely an adaptive secondary mirror with 672 actuators and a high-order pyramid wave-front sensor. During the on-sky commissioning such a system reached performances never achieved before on large ground-based optical telescopes. Images with 40mas resolution and Strehl Ratios higher than 80% have been acquired in H band (1.6 micron). Such images showed a contrast as high as 10e-4. Based on these results, we compare the performances offered by a Natural Guide Star (NGS) system upgraded with the state-of-the-art technology and those delivered by existing Laser Guide Star (LGS) systems. The comparison, in terms of sky coverage and performances, suggests rethinking the current role ascribed to NGS and LGS in the next generation of AO systems for the 8-10 meter class telescopes and Extremely Large Telescopes (ELTs).Comment: 10 pages, 9 figures, Preented at SSPIE Optics + Photonics 2011, San Diego 20-25 August 201

Resolving the Dusty Circumstellar Structure of the Enigmatic Symbiotic Star CH Cygni with the MMT Adaptive Optics System

We imaged the symbiotic star CH Cyg and two PSF calibration stars using the unique 6.5m MMT deformable secondary adaptive optics system. Our high-resolution (FWHM=0.3"), very high Strehl (98%+-2%) mid-infrared (9.8 and 11.7 um) images of CH Cyg allow us to probe finer length scales than ever before for this object. CH Cyg is significantly extended compared to our unresolved PSF calibration stars (Mu UMa and Alpha Her) at 9.8 and 11.7 um. We estimated the size of the extension by convolving a number of simple Gaussian models with the Mu UMa PSF and determining which model provided the best fit to the data. Adopting the Hipparcos distance for this object of 270 pc, we found a nearly Gaussian extension with a FWHM at 9.8 um of ~40.5+-2.7 AU (0.15+-0.01") and a FWHM at 11.7 um of 45.9+-2.7 AU (0.17+-0.01"). After subtracting out the Gaussian component of the emission (convolved with our PSF), we found a faint \~0.7" asymmetric extension which peaks in flux ~0.5" north of the stars. This extension is roughly coincident with the northern knotlike feature seen in HST WFPC2 images obtained in 1999.Comment: 18 pages, 7 figures, accepted by the Astrophysical Journa

Adaptive Optics Nulling Interferometric Constraints on the Mid-Infrared Exozodiacal Dust Emission around Vega

We present the results of mid-infrared nulling interferometric observations of the main-sequence star alpha Lyr (Vega) using the 6.5 m MMT with its adaptive secondary mirror. From the observations at 10.6 microns, we find that there is no resolved emission from the circumstellar environment (at separations greater than 0.8 AU) above 2.1% (3 sigma limit) of the level of the stellar photospheric emission. Thus, we are able to place an upper limit on the density of dust in the inner system of 650 times that of our own solar system's zodiacal cloud. This limit is roughly 2.8 times better than those determined with photometric excess observations such as those by IRAS. Comparison with far-infrared observations by IRAS shows that the density of warm dust in the inner system (< 30 AU) is significantly lower than cold dust at larger separations. We consider two scenarios for grain removal, the sublimation of ice grains and the presence of a planetary mass "sweeper." We find that if sublimation of ice grains is the only removal process, a large fraction (> 80%) of the material in the outer system is ice.Comment: 11 pages, 1 figure, Accepted to The Astrophysical Journal Letter

Mid-Infrared Imaging of the Post-AGB Star AC Herculis with the MMT Adaptive Optics System

We utilized the MMT's unique deformable secondary adaptive optics system to produce high-resolution (FWHM=0.3"), very high Strehl mid-infrared (9.8, 11.7 & 18 micron) images of the post-AGB star AC Her. The very high (98+/-2%) Strehls achieved with Mid-IR AO led naturally to an ultra-stable PSF independent of airmass, seeing, or location on the sky. We find no significant difference between AC Her's morphology and our unresolved PSF calibration stars (mu UMa & alpha Her) at 9.8, 11.7, & 18 microns. Our current observations do not confirm any extended Mid-IR structure around AC Her. These observations are in conflict with previously reported Keck (seeing-limited) 11.7 and 18 micron images which suggested the presence of a resolved ~0.6" edge-on circumbinary disk. We conclude that AC Her has no extended Mid-IR structure on scales greater than 0.2" (R<75 AU). These first results of Mid-IR AO science are very encouraging for future high accuracy Mid-IR imaging with this technique.Comment: To appear in the November 20, 2003 issue of the Astrophysical Journal Letters. The preprint has 7 pages and 3 figures (one in color; but prints OK in B&W

The Gray Needle: Large Grains in the HD 15115 Debris Disk from LBT/PISCES/Ks and LBTI/LMIRcam/L' Adaptive Optics Imaging

We present diffraction-limited \ks band and \lprime adaptive optics images of the edge-on debris disk around the nearby F2 star HD 15115, obtained with a single 8.4 m primary mirror at the Large Binocular Telescope. At \ks band the disk is detected at signal-to-noise per resolution element (SNRE) \about 3-8 from \about 1-2\fasec 5 (45-113 AU) on the western side, and from \about 1.2-2\fasec 1 (63-90 AU) on the east. At \lprime the disk is detected at SNRE \about 2.5 from \about 1-1\fasec 45 (45-90 AU) on both sides, implying more symmetric disk structure at 3.8 \microns . At both wavelengths the disk has a bow-like shape and is offset from the star to the north by a few AU. A surface brightness asymmetry exists between the two sides of the disk at \ks band, but not at \lprime . The surface brightness at \ks band declines inside 1\asec (\about 45 AU), which may be indicative of a gap in the disk near 1\asec. The \ks - \lprime disk color, after removal of the stellar color, is mostly grey for both sides of the disk. This suggests that scattered light is coming from large dust grains, with 3-10 \microns -sized grains on the east side and 1-10 \microns dust grains on the west. This may suggest that the west side is composed of smaller dust grains than the east side, which would support the interpretation that the disk is being dynamically affected by interactions with the local interstellar medium.Comment: Apj-accepted March 27 2012; minor correction