Models of infrared spectra of Sakurai's Object (V4334 Sgr) in 1997

Theoretical spectral energy distributions computed for a grid of hydrogen-deficient and carbon-rich model atmospheres have been compared with the observed infrared (1--2.5 $\mu$m) spectra of V4334 Sgr (Sakurai's Object) on 1997 April 21 and July 13. The comparison yields an effective temperature of \Tef = 5500 $\pm$ 200 K for the April date and \Tef = 5250 $\pm$ 200 K for July. The observed spectra are well fitted by Asplund et al. (1999) abundances, except that the carbon abundance is higher by 0.3 dex. Hot dust produces significant excess continuum at the long wavelength ends of the 1997 spectra. \keywords{Stars: individual: V4334 Sgr (Sakurai's Object) -- Stars: AGB and post-AGB evolution -- Stars: model atmospheres -- Stars: energy distributions -- Stars: effective temperatures}Comment: 6 pages, 7 eps figs, accepted for A

CO-activator model for reconstructing Pt(100) surfaces: local microstructures and chemical turbulence

We present the results of the modelling of CO adsorption and catalytic CO oxidation on inhomogeneous Pt(100) surfaces which contain structurally different areas. These areas are formed during the CO-induced transition from a reconstructed phase with hexagonal geometry of the overlayer to a bulk-like (1x1) phase with square atomic arrangement. In the present approach, the surface transition is explained in terms of nonequilibrium bistable behavior. The bistable region is characterized by a coexistence of the hexagonal and (1x1) phases and is terminated in a critical bifurcation point which is located at (T_c ~680 K, p_CO ~10 Torr). Due to increasing fluctuations, the behavior at high temperatures and pressures in the vicinity of this cusp point should be qualitatively different from the hysteresis-type behavior which is typically observed in the experiments under ultrahigh vacuum conditions. On the inhomogeneous surface, we find a regime of nonuniform oscillations characterized by random standing waves of adsorbate concentrations. The resulting spatial deformations of wave fronts allow to gain deeper insight into the nature of irregular oscillations on Pt(100) surface.Comment: 11 pages, 11 figures, to appear in Physical Review

The image of a writer in nobel lectures delivered by laureates in literature

Background. A growing interest in discursive nature of Nobel lectures resulted in a number of studies which emphasize their rhetorical force to influence public opinion and to popularize ideas in different spheres of human life. Analyzing Literature Laureates’ lectures, most researchers focus on linguistic means and the personality of the Nobelist himself/herself. However, characteristics of a writer proper have not been dealt with indepth. This article maintains our previous study, which indicates a close relationship between the content component of the Nobel lecture and the laureate’ outlook; the lecture itself can be regarded as a brief but extremely powerful expression of his/her human and professional qualities. Purpose. The aim of this paper is to examine how literature laureates interpret the notion of a writer in their Nobel lectures and to identify main common themes in creating this collective image. Methods. A method of linguistic description and observation, a descriptive method, and a contextual-interpretation method were employed to analyse the sample of 17 Nobel lectures. Results. The outcomes of our study indicate that Nobel lectures are extremely powerful expression of prizewinners’ human and professional qualities. We have devised a set of five themes, namely the writer’s social duty, his/her destiny, literary background, tools, and literary outcome to describe the collective image of a writer. Within the framework of our research, literary background falls into two subthemes (literary heritage and a personal writing process); discussing the writer’s toolkit, we focus on language and words. Discussion. Our findings show that laureates develop the concept “writer” to varying degrees but all of them stress a direct interconnection between an active social position and the writer’s destiny. Further research can involve the in-depth study of a definite Nobel lecture in terms of the compositional structure and employed linguistic means

Нобелівська лекція як віддзеркалення світогляду лауреата

Статтю присвячено дослідженню змістової складової такого специфічного мовленнєвого жанру як Нобелівська лекція. Увагу зосереджено на проблемно-тематичних характеристиках англомовних лекцій, які були прочитані лауреатами в галузі літератури. Проаналізовано чинники, що впливають на зміст лекції. Встановлено взаємозв’язок між темою доповіді та офіційним обґрунтуванням нагороди членами Шведської академії

Ultracool dwarfs

We present results of modeling of spectra of M-, L-, T-dwarfs. Theoretical spectra are fitted to observed spectra to study the main parameters of the low-mass objects beyond the bottom of Main Sequence. Application of ``lithium'' and ``deuterium'' tests for assessment of ultra-cool dwarfs are discussed.Comment: Talk for MAO2004 Meeting (Kyiv, July 15-17, 2004), see more details on http://www.mao.kiev.ua/mao-2004/public.htm, 6 pages, 3fig

12C/13C in atmospheres of red giants and peculiar stars

We determine the carbon isotopic ratios in the atmospheres of some evolved stars in both globular clusters and the disk of our Galaxy. Analysis of 12CO and 13CO bands at 2.3 micron was carried out using fits to observed spectra of red giants and Sakurai's object (V4334 Sgr). The dependence of theoretical spectra on the various input parameters was studied in detail. The computation of model atmospheres and a detailed abundance analysis was performed in a self-consistent fashion. A special procedure for determining the best fits to observed spectra was used. We show, that globular cluster giants with [Fe/H] < -1.3 have a low 12C/13C = 4 +/- 1 abundance ration. In the spectra of Sakurai's object (V4334 Sgr) taken between 1997-98, the 2.3 micron spectral region is veiled by hot dust emission. By fitting UKIRT spectra we determined 12C/13C = 4 +/- 1 for the July, 1998 spectrum. CO bands in the spectra of ultracool dwarfs are modelled as well.Comment: Poster for IAU Symposium No. 228, "From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution", V. Hill, P. Francois & F. Primas, eds. (2005); 2 pages, ppt is available on ftp://ftp.mao.kiev.ua/%2f/pub/users/yp/12C13C_for_IAU228.pp

Lithium in LP 944-20

The definitive version is available at www.blackwell-synergy.com. Copyright Blackwell Publishing DOI :10.1111/j.1365-2966.2007.12182.xPeer reviewe