HD 178892 - a cool Ap star with extremely strong magnetic field

We report a discovery of the Zeeman resolved spectral lines, corresponding to the extremely large magnetic field modulus =17.5 kG, in the cool Ap star HD 178892. The mean longitudinal field of this star reaches 7.5 kG, and its rotational modulation implies the strength of the dipolar magnetic component Bp>=23 kG. We have revised rotation period of the star using the All Sky Automated Survey photometry and determined P=8.2478 d. Rotation phases of the magnetic and photometric maxima of the star coincide with each other. We obtained Geneva photometric observation of HD 178892 and estimated Teff=7700+/-250 K using photometry and the hydrogen Balmer lines. Preliminary abundance analysis reveals abundance pattern typical of rapidly oscillating Ap stars.Comment: Accepted by Astronomy & Astrophysics; 4 pages, 4 figure

New Abundances for Old Stars - Atomic Diffusion at Work in NGC 6397

A homogeneous spectroscopic analysis of unevolved and evolved stars in the metal-poor globular cluster NGC 6397 with FLAMES-UVES reveals systematic trends of stellar surface abundances that are likely caused by atomic diffusion. This finding helps to understand, among other issues, why the lithium abundances of old halo stars are significantly lower than the abundance found to be produced shortly after the Big Bang.Comment: 8 pages, 7 colour figures, 1 table; can also be downloaded via http://www.eso.org/messenger

ОБЛІКОВО - АНАЛІТИЧНЕ ЗАБЕЗПЕЧЕННЯ ПРОЦЕСУ ОПТИМІЗАЦІЇ ПРИБУТКУ ПІДПРИЄМСТВА

The relevance and expediency of the theoretical and methodological basis improvement on the issues of the enterprise profit in the modern conditions of the domestic economy development has been proved and substantiated. The essence of the enterprise profit optimization is considered, proceeding from the position of the ‘profit’ and ‘optimization’ concepts symbiosis. The grounds of the accounting and analytical support of the enterprise profit optimization process are substantiated. The main sources of profit optimization are described. The essence of the accounting and analytical support in the management system for the enterprise results is highlighted. Some components of the profit optimization process are generalized, namely: subjects, objects, purpose, methods. The subjects of profit optimization in the context of accounting and analytical activity of the enterprise are characterized by definition of main and secondary process participants. The influence of separate subjects on the enterprise profit optimization is presented in the context of accounting and analytical support. The objects and stages of profit optimization in the enterprise accounting and analysis system are distinguished. It is proved and substantiated that the content of the profit optimization process is inextricably linked with the stages of profit distribution: the stages of profit distribution determine the stages of optimization of its value. The main stages of profit optimization in the process of its distribution and use are considered and described. The priority factors influencing the profitability of the entity are determined. The analytical approach of profit optimization is offered and its interrelation with the accounting policy of the enterprise is resulted. The directions of realization for such interconnection are determined. The scientific novelty of the results obtained is to improve and further develop theoretical and methodological approaches to the accounting and analytical provision of the enterprise profit optimization process. The practical significance of the results obtained is the possibility of using the research results in the practical activities of domestic enterprises in order to ensure the efficiency of the profit optimization process and improve enterprises’ accounting policies in the context of its separate parts.Обоснована актуальность и целесообразность совершенствования теоретического и методического обеспечения по вопросам исследования прибыли предприятия в современных условиях развития отечественной экономики. Рассмотрена сущность оптимизации прибыли предприятия, исходя из позиции симбиоза понятий «прибыль» и «оптимизация». Охарактеризованы субъекты оптимизации прибыли в контексте учетно-аналитической деятельности предприятия путем определения главных и второстепенных участников данного процесса. Выделены объекты и этапы оптимизации прибыли в системе учета и анализа предприятия. Определены приоритетные факторы влияния на прибыльность предприятия. Предложен аналитический подход к оптимизации прибыли и приведена его взаимосвязь с учетной политикой предприятия. Определены направления реализации такой взаимосвязи. Научная новизна полученных результатов заключается в совершенствовании и дальнейшем развитии теоретических и методических подходов к учетно-аналитическому обеспечению процесса оптимизации прибыли предприятия. Практическое значение полученных результатов заключается в возможности применения результатов исследования в практической деятельности отечественных предприятий с целью обеспечения эффективности процесса оптимизации прибыли и совершенствования учетной политики предприятия в разрезе отдельных ее частей.Доведено та обґрунтовано актуальність й доцільність удосконалення теоретичного та методичного підґрунтя з питань дослідження прибутку суб’єкта господарювання в сучасних умовах розвитку вітчизняної економіки. Розглянуто сутність оптимізації прибутку підприємства, виходячи з позиції симбіозу понять «прибуток» та «оптимізація». Обґрунтовано засади підґрунтя обліково-аналітичного забезпечення процесу оптимізації прибутку підприємства. Охарактеризовано основні джерела оптимізації величини прибутку. Висвітлено сутність обліково-аналітичного забезпечення в системі управління результатами діяльності суб’єкта господарювання. Узагальнено окремі складові процесу оптимізації прибутку, а саме: суб’єкти, об’єкти, мета, методи. Охарактеризовано суб’єкти оптимізації прибутку в контексті обліково-аналітичної діяльності підприємства через визначення головних та другорядних учасників даного процесу. Представлено вплив окремих суб’єктів на оптимізацію прибутку підприємства в контексті обліково-аналітичного забезпечення. Виокремлено об’єкти та етапи оптимізації прибутку в системі обліку та аналізу підприємства. Доведено та обґрунтовано, що зміст процесу оптимізації прибутку нерозривно пов’язаний з етапами розподілу прибутку: етапи розподілу прибутку визначають етапи оптимізації його величини. Розглянуто та охарактеризовано головні етапи оптимізації прибутку в процесі його розподілу та використання. Визначено пріоритетні чинники впливу на прибутковість суб’єкта господарювання. Запропоновано аналітичний підхід до оптимізації прибутку та наведено його взаємозв’язок із обліковою політикою підприємства. Визначено напрями реалізації такого взаємозв’язку. Наукова новизна отриманих результатів полягає в удосконаленні та подальшому розвитку теоретичних та методичних підходів щодо обліково-аналітичного забезпечення процесу оптимізації прибутку підприємства. Практичне значення отриманих результатів полягає в можливості застосування результатів дослідження в практичній діяльності вітчизняних підприємств з метою забезпечення ефективності процесу оптимізації прибутку та удосконалення облікової політики підприємства в розрізі окремих її частин

Atomic Diffusion and Mixing in Old Stars I. VLT/FLAMES-UVES Observations of Stars in NGC 6397

We present a homogeneous photometric and spectroscopic analysis of 18 stars along the evolutionary sequence of the metal-poor globular cluster NGC 6397 ([Fe/H] = -2), from the main-sequence turnoff point to red giants below the bump. The spectroscopic stellar parameters, in particular stellar-parameter differences between groups of stars, are in good agreement with broad-band and Stroemgren photometry calibrated on the infrared-flux method. The spectroscopic abundance analysis reveals, for the first time, systematic trends of iron abundance with evolutionary stage. Iron is found to be 31% less abundant in the turnoff-point stars than in the red giants. An abundance difference in lithium is seen between the turnoff-point and warm subgiant stars. The impact of potential systematic errors on these abundance trends (stellar parameters, the hydrostatic and LTE approximations) is quantitatively evaluated and found not to alter our conclusions significantly. Trends for various elements (Li, Mg, Ca, Ti and Fe) are compared with stellar-structure models including the effects of atomic diffusion and radiative acceleration. Such models are found to describe the observed element-specific trends well, if extra (turbulent) mixing just below the convection zone is introduced. It is concluded that atomic diffusion and turbulent mixing are largely responsible for the sub-primordial stellar lithium abundances of warm halo stars. Other consequences of atomic diffusion in old metal-poor stars are also discussed.Comment: 20 pages (emulateapj), 11 figures, accepted for publication in Ap

Magnetic chemically peculiar stars

Chemically peculiar (CP) stars are main-sequence A and B stars with abnormally strong or weak lines for certain elements. They generally have magnetic fields and all observables tend to vary with the same period. Chemically peculiar stars provide a wealth of information; they are natural atomic and magnetic laboratories. After a brief historical overview, we discuss the general properties of the magnetic fields in CP stars, describe the oblique rotator model, explain the dependence of the magnetic field strength on the rotation, and concentrate at the end on HgMn stars.Comment: 9 pages, 4 figures, 2 tables, chapter in "Determination of Atmospheric Parameters of B-, A-, F- and G-Type Stars", Springer (2014), eds. E. Niemczura, B. Smalley, W. Pyc

Detailed analysis of Balmer lines in cool dwarf stars

An analysis of H alpha and H beta spectra in a sample of 30 cool dwarf and subgiant stars is presented using MARCS model atmospheres based on the most recent calculations of the line opacities. A detailed quantitative comparison of the solar flux spectra with model spectra shows that Balmer line profile shapes, and therefore the temperature structure in the line formation region, are best represented under the mixing length theory by any combination of a low mixing-length parameter alpha and a low convective structure parameter y. A slightly lower effective temperature is obtained for the sun than the accepted value, which we attribute to errors in models and line opacities. The programme stars span temperatures from 4800 to 7100 K and include a small number of population II stars. Effective temperatures have been derived using a quantitative fitting method with a detailed error analysis. Our temperatures find good agreement with those from the Infrared Flux Method (IRFM) near solar metallicity but show differences at low metallicity where the two available IRFM determinations themselves are in disagreement. Comparison with recent temperature determinations using Balmer lines by Fuhrmann (1998, 2000), who employed a different description of the wing absorption due to self-broadening, does not show the large differences predicted by Barklem et al. (2000). In fact, perhaps fortuitously, reasonable agreement is found near solar metallicity, while we find significantly cooler temperatures for low metallicity stars of around solar temperature.Comment: 17 pages, 9 figures, to appear in A&

Velocities measured in small scale solar magnetic elements

We have obtained high resolution spectrograms of small scale magnetic structures with the Swedish 1-m Solar Telescope. We present Doppler measurements at 0\farcs{2} spatial resolution of bright points, ribbons and flowers and their immediate surroundings, in the C {\small{I}} 5380.3 {\AA} line (formed in the deep photosphere) and the two Fe {\small{I}} lines at 5379.6 {\AA} and 5386.3 {\AA}. The velocity inside the flowers and ribbons are measured to be almost zero, while we observe downflows at the edges. These downflows are increasing with decreasing height. We also analyze realistic magneto-convective simulations to obtain a better understanding of the interpretation of the observed signal. We calculate how the Doppler signal depends on the velocity field in various structures. Both the smearing effect of the non-negligible width of this velocity response function along the line of sight and of the smearing from the telescope and atmospheric point spread function are discussed. These studies lead us to the conclusion that the velocity inside the magnetic elements are really upflow of the order 1--2 km s${}^{-1}$ while the downflows at the edges really are much stronger than observed, of the order 1.5--3.3 km s${}^{-1}$

s-Process Nucleosynthesis in Carbon Stars

We present the first detailed and homogeneous analysis of the s-element content in Galactic carbon stars of N-type. Abundances of Sr,Y, Zr (low-mass s-elements, or ls) and of Ba, La, Nd, Sm and Ce (high-mass s-elements, hs) are derived using the spectral synthesis technique from high-resolution spectra. The N-stars analyzed are of nearly solar metallicity and show moderate s-element enhancements, similar to those found in S stars, but smaller than those found in the only previous similar study (Utsumi 1985), and also smaller than those found in supergiant post-AGB stars. This is in agreement with the present understanding of the envelope s-element enrichment in giant stars, which is increasing along the spectral sequence M-->MS-->S-->SC-->C during the AGB phase. We compare the observational data with recent $s$-process nucleosynthesis models for different metallicities and stellar masses. Good agreement is obtained between low mass AGB star models (M < 3 M_o) and s-elements observations. In low mass AGB stars, the 13C(alpha, n)16O reaction is the main source of neutrons for the s-process; a moderate spread, however, must exist in the abundance of 13C that is burnt in different stars. By combining information deriving from the detection of Tc, the infrared colours and the theoretical relations between stellar mass, metallicity and the final C/O ratio, we conclude that most (or maybe all) of the N-stars studied in this work are intrinsic, thermally-pulsing AGB stars; their abundances are the consequence of the operation of third dredge-up and are not to be ascribed to mass transfer in binary systems.Comment: 31 pages, 10 figures, 6 tables. Accepted in Ap

Revisiting the Rigidly Rotating Magnetosphere model for sigma Ori E. I. Observations and Data Analysis

We have obtained 18 new high-resolution spectropolarimetric observations of the B2Vp star sigma Ori E with both the Narval and ESPaDOnS spectropolarimeters. The aim of these observations is to test, with modern data, the assumptions of the Rigidly Rotating Magnetosphere (RRM) model of Townsend & Owocki (2005), applied to the specific case of sigma Ori E by Townsend et al. (2005). This model includes a substantially offset dipole magnetic field configuration, and approximately reproduces previous observational variations in longitudinal field strength, photometric brightness, and Halpha emission. We analyze new spectroscopy, including H I, He I, C II, Si III and Fe III lines, confirming the diversity of variability in photospheric lines, as well as the double S-wave variation of circumstellar hydrogen. Using the multiline analysis method of Least-Squares Deconvolution (LSD), new, more precise longitudinal magnetic field measurements reveal a substantial variance between the shapes of the observed and RRM model time-varying field. The phase resolved Stokes V profiles of He I 5876 A and 6678 A lines are fit poorly by synthetic profiles computed from the magnetic topology assumed by Townsend et al. (2005). These results challenge the offset dipole field configuration assumed in the application of the RRM model to sigma Ori E, and indicate that future models of its magnetic field should also include complex, higher-order components.Comment: 13 pages, 8 figures. Accepted for publication in MNRA

Comprehensive study of the magnetic stars HD 5797 and HD 40711 with large chromium and iron overabundances

We present the results of a comprehensive study of the chemically peculiar stars HD 5797 and HD 40711. The stars have the same effective temperature, Teff = 8900 K, and a similar chemical composition with large iron (+1.5 dex) and chromium (+3 dex) overabundances compared to the Sun. The overabundance of rare-earth elements typically reaches +3 dex. We have measured the magnetic field of HD 5797. The longitudinal field component Be has been found to vary sinusoidally between -100 and +1000 G with a period of 69 days. Our estimate of the evolutionary status of the stars suggests that HD 5797 and HD 40711, old objects with an age t \approx 5 \times 108 yr, are near the end of the core hydrogen burning phase.Comment: 26 pages, 5 Encapsulated Postscript figure