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

Temporal logic model of performance in high school = Темпорально-логическая модель деятельности обучаемого в вузе

Pavlenko V. N., Tkachenko Y. M. Temporal logic model of performance in high school = Темпорально-логическая модель деятельности обучаемого в вузе. Journal of Education, Health and Sport. 2015;5(7):258-270. ISSN 2391-8306. DOI 10.5281/zenodo.19970http://ojs.ukw.edu.pl/index.php/johs/article/view/2015%3B5%287%29%3A258-270https://pbn.nauka.gov.pl/works/584328http://dx.doi.org/10.5281/zenodo.19970Formerly Journal of Health Sciences. ISSN 1429-9623 / 2300-665X. Archives 2011 – 2014 http://journal.rsw.edu.pl/index.php/JHS/issue/archive Deklaracja.Specyfika i zawartość merytoryczna czasopisma nie ulega zmianie.Zgodnie z informacją MNiSW z dnia 2 czerwca 2014 r., że w roku 2014 nie będzie przeprowadzana ocena czasopism naukowych; czasopismo o zmienionym tytule otrzymuje tyle samo punktów co na wykazie czasopism naukowych z dnia 31 grudnia 2014 r.The journal has had 5 points in Ministry of Science and Higher Education of Poland parametric evaluation. Part B item 1089. (31.12.2014).© The Author (s) 2015;This article is published with open access at Licensee Open Journal Systems of Kazimierz Wielki University in Bydgoszcz, Poland and Radom University in Radom, PolandOpen Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited.This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercialuse, distribution and reproduction in any medium, provided the work is properly cited.The authors declare that there is no conflict of interests regarding the publication of this paper.Received: 15.06.2015. Revised 05.07.2015. Accepted: 12.07.2015. TEMPORAL LOGIC MODEL OF PERFORMANCE IN HIGH SCHOOLТЕМПОРАЛЬНО-ЛОГИЧЕСКАЯ МОДЕЛЬ ДЕЯТЕЛЬНОСТИ ОБУЧАЕМОГО В ВУЗЕ V. N. Pavlenko, Y. M. TkachenkoВ. Н. Павленко, Ю. М. Ткаченко National Aerospace University «Kharkiv Aviation Institute», UkraineНациональный аэрокосмический университет им. Н. Е. Жуковского «ХАИ», Украина V.N. Pavlenko,NationalAerospaceUniversity«Kharkiv Aviation Institute», Ukraine Chkalova str. 17,Kharkiv,Ukraine, 61070E-mail: [email protected] Y.M. Tkachenko,NationalAerospaceUniversity«Kharkiv Aviation Institute», Ukraine Chkalova str. 17,Kharkiv,Ukraine, 61070E-mail: [email protected] Abstract: The one of the stages of the approach to the organization of computer decision support to determine the trajectory of training of students in universities, namely the synthesis of model student. For the synthesis of the student model used mathematical apparatus of temporal logic. The form of a software implementation, the student model is representation in the form of an intelligent agent. Further stages of developing a new approach based on the development of the model of the student group as a community of intelligent agents, and on the notion of the learning process of students in the form of multi-agent system. A multi-agent system will be used to support decision-making by different levels (deans, vice-rector for scientific and pedagogical work) in the event of disputes in the learning process of individual students and student groups. Keywords: student, student group, the trajectory of education, educational process, process model, multi-agent systems, intelligent agents, temporal logic.  Аннотация: изложен один из этапов реализации подхода к организации компьютерной поддержки принятия решений по определению траектории обучения студентов в ВУЗах, а именно синтез модели обучаемого. Для синтеза модели обучаемого использован математический аппарат темпоральной логики. Формой программной реализации модели обучаемого является его представление в виде интеллектуального агента. Дальнейшие этапы разрабатываемого подхода основаны на разработке модели студенческой группы как сообщества интеллектуальных агентов, и на представлении процесса обучения студентов в форме мультиагентной системы. Мультиагентная система будет использоваться для поддержки принятия решений руководителями разных уровней (деканами, проректорами по научно-педагогической работе) при возникновении спорных ситуаций в процессе обучения как отдельных студентов, так и студенческих групп. Ключевые слова: студент, студенческая группа, траектория обучения, образовательный процесс, процессная модель, мультиагентные системы, интеллектуальные агенты, темпоральная логика

Atomic lines in infrared spectra for ultracool dwarfs

We provide a set of atomic lines which are suitable for the description of ultracool dwarf spectra from 10000 to 25000 \AA. This atomic linelist was made using both synthetic spectra calculations and existing atlases of infrared spectra of Arcturus and Sunspot umbra. We present plots, which show the comparison of synthetic spectra and observed Arcturus and Sunspot umbral spectra for all atomic lines likely to be observable in high resolution infrared spectra.Comment: 21 pages, 2 tables, 129 figures, figures are available only at http://www.astro.livjm.ac.uk/~hraj/spectralatlas/index.html, accepted to A&

VLT X-shooter spectroscopy of the nearest brown dwarf binary

The aim of the project is to characterise both components of the nearest brown dwarf sytem to the Sun, WISE J104915.57-531906.1 (=Luhman16AB) at optical and near-infrared wavelengths. We obtained high signal-to-noise intermediate-resolution (R~6000-11000) optical (600-1000 nm) and near-infrared (1000-2480nm) spectra of each component of Luhman16AB, the closest brown dwarf binary to the Sun, with the X-Shooter instrument on the Very Large Telescope. We classify the primary and secondary of the Luhman16 system as L6-L7.5 and T0+/-1, respectively, in agreement with previous measurements published in the literature. We present measurements of the lithium pseudo-equivalent widths, which appears of similar strength on both components (8.2+/-1.0 Angstroms and 8.4+/-1.5 Angstroms for the L and T components, respectively). The presence of lithium (Lithium 7) in both components imply masses below 0.06 Msun while comparison with models suggests lower limits of 0.04 Msun. The detection of lithium in the T component is the first of its kind. Similarly, we assess the strength of other alkali lines (e.g. pseudo-equivalent widths of 6-7 Angstroms for RbI and 4-7 Angstroms for CsI) present in the optical and near-infrared regions and compare with estimates for L and T dwarfs. We also derive effective temperatures and luminosities of each component of the binary: -4.66+/-0.08 dex and 1305(+180)(-135) for the L dwarf and -4.68+/-0.13 dex and 1320(+185)(-135) for the T dwarf, respectively. Using our radial velocity determinations, the binary does not appear to belong to any of the well-known moving group. Our preliminary theoretical analysis of the optical and J-band spectra indicates that the L- and T-type spectra can be reproduced with a single temperature and gravity but different relative chemical abundances which impact strongly the spectral energy distribution of L/T transition objects.Comment: 12 pages, 9 figure, 3 tables, accepted to A&

Masses, Oxygen and Carbon abundances in CHEPS dwarf stars

Reproduced with permission from Astronomy & Astrophysics. © 2019 ESOContext. We report the results from the determination of stellar masses, carbon, and oxygen abundances in the atmospheres of 107 stars from the Calan-Hertfordshire Extrasolar Planet Search (CHEPS) programme. Our stars are drawn from a population with a significantly super-solar metallicity. At least 10 of these stars are known to host orbiting planets. Aims. In this work, we set out to understand the behaviour of carbon and oxygen abundance in stars with different spectral classes, metallicities, and V sin i within the metal-rich stellar population. Methods. Masses of these stars were determined using data from Gaia DR2. Oxygen and carbon abundances were determined by fitting the absorption lines. We determined oxygen abundances with fits to the 6300.304 Å O I line, and we used 3 lines of the C I atom and 12 lines of the C 2 molecule for the determination of carbon abundances. Results. We determine masses and abundances of 107 CHEPS stars. There is no evidence that the [C/O] ratio depends on V sin i or the mass of the star within our constrained range of masses, i.e. 0.82 5 km s -1) are massive stars.Peer reviewedFinal Published versio

High-Dispersion Optical Spectra of Nearby Stars Younger Than The Sun

We present high-dispersion (R~16,000) optical (3900-8700 A) spectra of 390 stars obtained with the Palomar 60 inch telescope. The majority of stars observed are part of the Spitzer Legacy Science Program "The Formation and Evolution of Planetary Systems." Through detailed analysis we determine stellar properties for this sample, including radial and rotational velocities, Li I 6708 and Ha equivalent widths, the chromospheric activity index R'_HK, and temperature- and gravity-sensitive line ratios. Several spectroscopic binaries are also identified. From our tabulations, we illustrate basic age- and rotation-related correlations among measured indices. One novel result is that Ca II chromospheric emission appears to saturate at vsini values above ~30 km/s, similar to the well established saturation of X-rays that originate in the spatially separate coronal regions.Comment: 1 electronic table; published in the Astronomical Journa

The turbulent spectrum created by non-Abelian plasma instabilities

Recent numerical work on the fate of plasma instabilities in weakly-coupled non-Abelian gauge theory has shown the development of a cascade of energy from long to short wavelengths. This cascade has a steady-state spectrum, analogous to the Kolmogorov spectrum for turbulence in hydrodynamics or for energy cascades in other systems. In this paper, we theoretically analyze processes responsible for this cascade and find a steady-state spectrum f_k ~ k^-2, where f_k is the phase-space density of particles with momentum k. The exponent -2 is consistent with results from numerical simulations. We also discuss implications of the emerging picture of instability development on the "bottom-up" thermalization scenario for (extremely high energy) heavy ion collisions, emphasizing fundamental questions that remain to be answered.Comment: 17 pages, 5 figure

Optical studies of the X-ray transient XTE J2123-058 -I. Photometry

We present optical photometry of the X-ray transient XTE J2123-058, obtained in July-October 1998. The light curves are strongly modulated on the 5.95hrs orbital period, and exhibit dramatic changes in amplitude and form during the decline. We used synthetic models which include the effect of partial eclipses and X-ray heating effects, to estimate the system parameters, and we constrain the binary inclination to be i=73+-4 degrees. The model is successful in reproducing the light curves at different stages of the decay by requiring the accretion disc to become smaller and thinner by 30% as the system fades by 1.7 mags in the optical. From Aug 26 the system reaches quiescence with a mean magnitude of R=21.7+-0.1 and our data are consistent with the optical variability being dominated by the companion's ellipsoidal modulation.Comment: 6 pages, 6 figure