NGC 6738: not a real open cluster

A photometric, astrometric and spectroscopic investigation of the poorly studied open cluster NGC 6738 has been performed in order to ascertain its real nature. NGC 6738 is definitely not a physical stellar ensemble: photometry does not show a defined mean sequence, proper motions and radial velocities are randomly distributed, spectro-photometric parallaxes range between 10 and 1600 pc, and the apparent luminosity function is identical to that of the surrounding field. NGC 6738 therefore appears to be an apparent concentration of a few bright stars projected on patchy background absorption.Comment: A&A, in press (compared with first submission to astro-ph, now Table 2 and Figure 4 are replaced with corrected versions

Photometric Calibration of the Supernova Legacy Survey Fields

We present the photometric calibration of the Supernova Legacy Survey (SNLS) fields. The SNLS aims at measuring the distances to SNe Ia at (0.3<z<1) using MegaCam, the 1 deg^2 imager on the Canada-France-Hawaii Telescope (CFHT). The uncertainty affecting the photometric calibration of the survey dominates the systematic uncertainty of the key measurement of the survey, namely the dark energy equation of state. The photometric calibration of the SNLS requires obtaining a uniform response across the imager, calibrating the science field stars in each survey band (SDSS-like ugriz bands) with respect to standards with known flux in the same bands, and binding the calibration to the UBVRI Landolt standards used to calibrate the nearby SNe from the literature necessary to produce cosmological constraints. The spatial non-uniformities of the imager photometric response are mapped using dithered observations of dense stellar fields. Photometric zero-points against Landolt standards are obtained. The linearity of the instrument is studied. We show that the imager filters and photometric response are not uniform and publish correction maps. We present models of the effective passbands of the instrument as a function of the position on the focal plane. We define a natural magnitude system for MegaCam. We show that the systematics affecting the magnitude-to-flux relations can be reduced if we use the spectrophotometric standard star BD +17 4708 instead of Vega as a fundamental flux standard. We publish ugriz catalogs of tertiary standards for all the SNLS fields.Comment: 46 pages, 23 figures. Accepted by Astronomy and Astrophysics. Online material available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ or alternatively from: http://supernovae.in2p3.fr/snls3/regnault09_cds.tar.g

Huge Seebeck coefficients in non-aqueous electrolytes

The Seeebeck coefficients of the non-aqueous electrolytes tetrabutylammonium nitrate, tetraoctylphosphonium bromide and tetradodecylammonium nitrate in 1-octanol, 1-dodecanol and ethylene-glycol are measured in a temperature range from T=30 to T=45 C. The Seebeck coefficient is generally of the order of a few hundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here we report huge values of 7 mV/K at 0.1M concentration for tetrabutylammonium nitrate in 1-dodecanol. These striking results open the question of unexpectedly large kosmotrope or "structure making" effects of tetraalkylammonium ions on the structure of alcohols.Comment: Submitted to J. Chem. Phy

Magnetic properties of HO2 thin films

We report on the magnetic and transport studies of hafnium oxide thin films grown by pulsed-laser deposition on sapphire substrates under different oxygen pressures, ranging from 10-7 to 10-1 mbar. Some physical properties of these thin films appear to depend on the oxygen pressure during growth: the film grown at low oxygen pressure (P ~= 10-7 mbar) has a metallic aspect and is conducting, with a positive Hall signal, while those grown under higher oxygen pressures (7 x 10-5 <= P <= 0.4 mbar) are insulating. However, no intrinsic ferromagnetic signal could be attributed to the HfO2 films, irrespective of the oxygen pressure during the deposition.Comment: 1

II Zwicky 23 and Family

II Zwicky 23 (UGC 3179) is a luminous, nearby compact narrow emission line starburst galaxy with blue optical colors and strong emission lines. We present a photometric and morphological study of II Zw 23 and its interacting companions using data obtained with the WIYN 3.5-m telescope in Kitt Peak, Arizona. II Zwicky 23 has a highly disturbed outer structure with long trails of debris that may be feeding tidal dwarfs. Its central regions appear disky, a structure that is consistent with the overall rotation pattern observed in the H-alpha velocity field measured from Densepak observations obtained with WIYN. We discuss the structure of II Zwicky 23 and its set of companions and possible scenarios of debris formation in this system.Comment: 5 pages, 2 figures. To appear in the proceedings of ESO Astrophysics Symposia: "Groups of Galaxies in the Nearby Universe", eds. I. Saviane, V. Ivanov, J. Burissova (Springer

Die psychosoziale/-sexuelle Entwicklung von Knaben mit einer Hypospadie

Zusammenfassung: Knaben mit einer Hypospadie sind spezifischen psychischen Belastungen im Zusammenhang mit dem chirurgischen Eingriff im Genitalbereich und einem kosmetisch und/oder funktionell beeinträchtigten Penis ausgesetzt. Während in den letzten Jahrzehnten intensive Anstrengungen zur Verbesserung der Operationstechniken unternommen worden sind, wurde die psychosoziale und psychosexuelle Entwicklung von Kindern und Jugendlichen nach Hypospadiekorrektur erst selten untersucht. Die Resultate der wenigen Studien sind insgesamt sehr widersprüchlich. Sie weisen aber auch deutlich daraufhin, dass die betroffenen Knaben unter spezifischen Problemen wie dem andersartigen Aussehen ihres Penis leiden. Das Angebot von medizinischen Verlaufskontrollen und psychosozialer Beratung muss ihnen deshalb bis ins junge Erwachsenenalter zur Verfügung gestellt werden. Für die zukünftige Forschung gilt es, in methodisch fundierten Studien Lebensqualität und Entwicklung der Knaben systematisch zu untersuchen. Dabei müssen insbesondere psychosoziale Risikofaktoren identifiziert werde

Followup Observations of SDSS and CRTS Candidate Cataclysmic Variables

We present photometry of 11 and spectroscopy of 35 potential cataclysmic variables from the Sloan Digital Sky Survey, the Catalina Real-Time Transient Survey and vsnet-alerts. The photometry results include quasi-periodic oscillations during the decline of V1363 Cyg, nightly accretion changes in the likely Polar (AM Herculis binary) SDSS J1344+20, eclipses in SDSS J2141+05 with an orbital period of 76+/-2 min, and possible eclipses in SDSS J2158+09 at an orbital period near 100 min. Time-resolved spectra reveal short orbital periods near 80 min for SDSS J0206+20, 85 min for SDSS J1502+33, and near 100 min for CSS J0015+26, RXS J0150+37, SDSS J1132+62, SDSS J2154+15 and SDSS J2158+09. The prominent HeII line and velocity amplitude of SDSS J2154+15 are consistent with a Polar nature for this object, while the lack of this line and a low velocity amplitude argue against this classification for RXS J0150+37. Single spectra of 10 objects were obtained near outburst and the rest near quiescence, confirming the dwarf novae nature of these objects.Comment: 34 pages, 14 figures, in press at A

Properties, evolution and morpho-kinematical modelling of the very fast nova V2672 Oph (Nova Oph 2009), a clone of U Sco

V2672 Oph reached maximum brightness V=11.35 on 2009 August 16.5. With observed t2(V)=2.3 and t3(V)=4.2 days decline times, it is one of the fastest known novae, being rivalled only by V1500 Cyg (1975) and V838 Her (1991) among classical novae, and U Sco among the recurrent ones. The line of sight to the nova passes within a few degrees of the Galactic centre. The reddening of V2672 Oph is E(B-V)=1.6 +/-0.1, and its distance ~19 kpc places it on the other side of the Galactic centre at a galacto-centric distance larger than the solar one. The lack of an infrared counterpart for the progenitor excludes the donor star from being a cool giant like in RS Oph or T CrB. With close similarity to U Sco, V2672 Oph displayed a photometric plateau phase, a He/N spectrum classification, extreme expansion velocities and triple peaked emission line profiles during advanced decline. The full width at zero intensity of Halpha was 12,000 km/s at maximum, and declined linearly in time with a slope very similar to that observed in U Sco. We infer a WD mass close to the Chandrasekhar limit and a possible final fate as a SNIa. Morpho-kinematical modelling of the evolution of the Halpha profile suggests that the overall structure of the ejecta is that of a prolate system with polar blobs and an equatorial ring. The density in the prolate system appeared to decline faster than that in the other components. V2672 Oph is seen pole-on, with an inclination of 0+/-6 deg and an expansion velocity of the polar blobs of 4800 +900/-800 km/s. On the basis of its remarkable similarity to U Sco, we suspect this nova may be a recurrent. Given the southern declination, the faintness at maximum, the extremely rapid decline and its close proximity to the Ecliptic, it is quite possible that previous outbursts of V2672 Oph have been missed.Comment: in press in MNRA

Atomic layer deposition of ZnS nanotubes

We report on growth of high-aspect-ratio ($\gtrsim300$) zinc sulfide nanotubes with variable, precisely tunable, wall thicknesses and tube diameters into highly ordered pores of anodic alumina templates by atomic layer deposition (ALD) at temperatures as low as 75 $^{\circ}$C. Various characterization techniques are employed to gain information on the composition, morphology, and crystal structure of the synthesized samples. Besides practical applications, the ALD-grown tubes could be envisaged as model systems for the study of a certain class of size-dependent quantum and classical phenomena.Comment: 1 LaTeX source file, 8 eps figures, and the manuscript in PDF forma

Coordinated thermal and optical observations of Trans-Neptunian object (20000) Varuna from Sierra Nevada

We report on coordinated thermal and optical measurements of trans-Neptunian object (20000) Varuna obtained in January-February 2002, respectively from the IRAM 30-m and IAA 1.5 m telescopes. The optical data show a lightcurve with a period of 3.176+/-0.010 hr, a mean V magnitude of 20.37+/-0.08 and a 0.42+/-0.01 magnitude amplitude. They also tentatively indicate that the lightcurve is asymmetric and double-peaked. The thermal observations indicate a 1.12+/-0.41 mJy flux, averaged over the object's rotation. Combining the two datasets, we infer that Varuna has a mean 1060(+180/-220) km diameter and a mean 0.038(+0.022/-0.010) V geometric albedo, in general agreement with an earlier determination using the same technique.Comment: Accepted for publication in Astronomy & Astrophysics (7 pages, including 3 figures