Quantitative spectroscopy of Deneb

Quantitative spectroscopy of luminous BA-type supergiants offers a high potential for modern astrophysics. The degree to which we can rely on quantitative studies of this class of stars as a whole depends on the quality of the analyses for benchmark objects. We constrain the basic atmospheric parameters and fundamental stellar parameters as well as chemical abundances of the prototype A-type supergiant Deneb to unprecedented accuracy (Teff = 8525 +/- 75 K, log(g) = 1.10 +/- 0.05 dex, M_spec = 19 +/- 3 M_sun, L = 1.96 +/- 0.32 *10^5 L_sun, R = 203 +/- 17 R_sun, enrichment with CN-processed matter) by applying a sophisticated hybrid NLTE spectrum synthesis technique which has recently been developed and tested. The study is based on a high-resolution and high-S/N spectrum obtained with the Echelle spectrograph FOCES on the Calar Alto 2.2m telescope. Practically all inconsistencies reported in earlier studies are resolved. Multiple metal ionization equilibria and numerous hydrogen lines from the Balmer, Paschen, Brackett and Pfund series are brought into match simultaneously for the stellar parameter determination. Stellar wind properties are derived from H_alpha line-profile fitting using line-blanketed hydrodynamic non-LTE models. A self-consistent view of Deneb is thus obtained, allowing us to discuss its evolutionary state in detail by comparison with the most recent generation of evolution models for massive stars. (abridged)Comment: 17 pages, 12 figures. Accepted for publication in A&

Effects of helium ion irradiation on tungsten-based composites : neutron diffraction; as a real-time diffractometer

The weight ratio 6% was formed for this paper by B4C-2% (99.5% purity, 20 µm particle size), TiC-1% (99.5% purity, 15 µm particle size), C (99.5% purity, 21 µm particle size) and the remaining part is tungsten W (99.5% purity, 17 µm particle size) structure had been established. In order to get homogeneous sinter, it was subjected to a temperature gradient of up to 1750 °C for 2 hours with a temperature step of 5 °C per minute. In the study, neutron diffraction (ND) was performed using the timeof-flight technique (TOF) in the IBR-2M research reactor. The obtained data were refined with the FULLPROF Rietveld suite. The results convey that it is different from the results obtained by X-Ray diffraction.http://jomardpublishing.com/journals.aspx?lang=en&id=13Physic

Realization of photometric base unit of candela traceable to cryogenic radiometer at UME

At National Metrology Institute of Turkey (UME, Ulusal Metroloji Enstitüsü), luminous intensity unit of candela was realized using detector-based approach and photometric scale was re-established depending on this new realization. Candela was measured on photometric bench using interferometric distance measurement system and filter-radiometer traceable to UME primary level electrical-substitution cryogenic radiometer. Thermally stabilized filter radiometer, which has been designed for spectral irradiance measurements, is consists of trap detector, filter housing and precision aperture. Different measurement techniques were used to fully characterize each parameter of filter-radiometer; like effective aperture area, spectral transmittance of $V(\lambda)$ filter and responsivity of trap detector

High-accuracy optical power measurements by using electrical-substitution cryogenic radiometer

An optical power scale is established at Ulusal Metroloji Enstitusu (UME) using the helium-cooled primary-level electrical-substitution cryogenic radiometer. The scale is established at discrete laser wavelengths of vertically polarized tuneable Ar+, fixed He-Ne, and Nd:YAG (with second harmonic) laser sources. To increase measurement accuracy, laser intensities are stabilized to better than 0.009% using an electro-optical modulator. The spatial profiles of polarized laser beams are cleaned with a spatial filter. The optical power is measured using the static substitution method with an uncertainty of a few parts in 10-4. Repeatability of optical power measurements in the static substitution method, the measurement of window transmittance, and the measurement of power in a scattered beam are the most significant uncertainty components. (C) 2005 Society of Photo-Optical Instrumentation Engineers

"Superionic Conductivity in One-Dimensional Nanofibrous TlGaTe2 Crystals"

International audienc

"Super ionic conductivity in (1D) nanofibrous TlGaTe2",

International audienc