Sparse Aperture Masking (SAM) at NAOS/CONICA on the VLT

The new operational mode of aperture masking interferometry has been added to the CONICA camera which lies downstream of the Adaptive Optics (AO) corrected focus provided by NAOS on the VLT-UT4 telescope. Masking has been shown to deliver superior PSF calibration, rejection of atmospheric noise and robust recovery of phase information through the use of closure phases. Over the resolution range from about half to several resolution elements, masking interferometry is presently unsurpassed in delivering high fidelity imaging and direct detection of faint companions. Here we present results from commissioning data using this powerful new operational mode, and discuss the utility for masking in a variety of scientific contexts. Of particular interest is the combination of the CONICA polarimetry capabilities together with SAM mode operation, which has revealed structures never seen before in the immediate circumstellar environments of dusty evolved stars.Comment: 11 pages, 10 figures, SPIE 201

A New Collisional Ring Galaxy at z = 0.111: Auriga's Wheel

We report the serendipitous discovery of a collision ring galaxy, identified as 2MASX J06470249+4554022, which we have dubbed 'Auriga's Wheel', found in a SUPRIME-CAM frame as part of a larger Milky Way survey. This peculiar class of galaxies is the result of a near head-on collision between typically, a late type and an early type galaxy. Subsequent GMOS-N long-slit spectroscopy has confirmed both the relative proximity of the components of this interacting pair and shown it to have a redshift of 0.111. Analysis of the spectroscopy reveals that the late type galaxy is a LINER class Active Galactic Nuclei while the early type galaxy is also potentially an AGN candidate, this is very uncommon amongst known collision ring galaxies. Preliminary modeling of the ring finds an expansion velocity of ~200 kms^-1 consistent with our observations, making the collision about 50 Myr old. The ring currently has a radius of about 10 kpc and a bridge of stars and gas is also visible connecting the two galaxies.Comment: 9 pages, 5 figures and 4 tables. Accepted for publication in Ap

Spheroidal structures in spiral galaxies: a study of the relationship of bars to triaxial bulges

Dottorato di ricerca in fisica. 10 ciclo. Coordinatore Paolo SchiavonConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Wheat bran biodegradation by Pleurotus ostreatus: A solid-state Carbon-13 NMR study

Solid-state 13C nuclear magnetic resonance (NMR) and elemental analysis techniques were used to monitor the degradation of wheat bran by the white-rot fungus Pleurotus ostreatus during a 62-day cultivation period. The weight loss and in vitro organic matter digestibility of the substrate were also evaluated after fungal treatment. The 13C NMR spectra of degraded wheat bran samples showed a lower content in carbohydrates and a higher content in aliphatic and carboxylic groups than the untreated control sample. In parallel, changes in the wheat bran elemental composition evidenced a decrease in carbon content and a concomitant increase in nitrogen and oxygen content during mycelium growth. These results clearly indicate the occurrence of progressive changes in the composition of wheat bran during fungal treatment and are interpreted in terms of preferential degradation of amorphous vs. crystalline polysaccharides by the fungal mycelium and accumulation of proteins in the substrate. At the end of the cultivation period, the treated samples experienced an average weight loss of 20% and an increase in organic matter digestibility of 17%

IOT Overview: High Resolution Spectrographs

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The Wide Field Imager Lyman-Alpha Search (WFILAS) for Galaxies at Redshift ~ 5.7. II. Survey design and sample analysis

Context. Wide-field narrowband surveys are an efficient way of searching large volumes of high-redshift space for distant galaxies. Aims. We describe the Wide Field Imager Lyman-Alpha Search (WFILAS) over 0.74 sq. degree for bright emission-line galaxie

Towards Precision Photometry with FORS: A Status Report

The two FOcal Reducer and low-dis-persion Spectrographs (FORS) are the primary imaging instruments for the VLT. Because they are not direct imaging instruments, the accuracy of photometry which can routinely be obtained is limited by significant sky concentration and other effects. This article reports on the progress of a long-term project to improve the photometric calibration of the FORS instruments

FORS1 is getting Blue: New Blue Optimised Detectors and High Throughput Filters

Ground-based observations in the ultraviolet part of the electromagnetic spectrum are notoriously difficult owing to absorption of the atmosphere, of optical elements and the poorer efficiency of detectors. Now that CCD detectors with excellent UV response and cosmetic quality have become available, it was time to optimise FORS1 for imaging, low-resolution spectroscopic and polarimetric observations in the blue-UV. As a bonus, a new set of broadband filters with very high trans-mission and carefully defined filter bands were installed