Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon III. HD 50138

We analyse spectroscopic observations of the B[e] star HD 50138 (MWC 158, V743 Mon, or IRAS 06491-0654), a member of the FS CMa group, obtained over the last twenty years. Four different epochs are identified in the observational data, where the variability of the spectral features is substantially different. Additionally, two long periods of (3 000 +/- 500) and (5 000 +/- 1000) days are found in the variations of the equivalent widths of the H alpha and [OI] 6300 A lines and radial velocities of the H alpha line violet peak. Modest signatures of a regular period of ~34 days in the radial velocities of the H alpha red peak and H beta central depression are found in the season 2013/2014. The H alpha V/R changes indicate a periodicity of ~50 days. The correlations between individual spectral features significantly restricts the model of the object and suggest that it is most likely a binary system with a highly distorted disc with spiral arms around the primary component. At the same time, no obvious signs of the secondary component has been found in the object's spectrum

Reliability of Human Subject - Artificial System Interactions

Main problems related to reliability of interaction between human subject and artificial system (namely of the transportation character) are discussed. The paper consists of three mayor parts:The first one is devoted to the theoretical backgrounds of the problem from the both theory of system reliability and neurology/psychology views.Second part presents the discussion of relevant methodologies of the classification and prediction of the reliability decline. The methodology based on EEG pattern analysis is chosen as the appropriate one for the presented task. The key phenomenon of "micro-sleep" is discussed in detail.The last part presents some latest experimental results in context of presented knowledge. Proposals for the future studies are presented at the end of the presented article. The special interest should be devoted to the analysis and in-time prediction of fatal attention decreases and to the design and construction of the respective on-board applicable warning system

The spectroscopic evolution of the symbiotic-like recurrent nova V407 Cygni during its 2010 outburst. I. The shock and its evolution

On 2010 Mar 10, V407 Cyg was discovered in outburst, eventually reaching V< 8 and detected by Fermi. Using medium and high resolution ground-based optical spectra, visual and Swift UV photometry, and Swift X-ray spectrophotometry, we describe the behavior of the high-velocity profile evolution for this nova during its first three months. The peak of the X-ray emission occurred at about day 40 with a broad maximum and decline after day 50. The main changes in the optical spectrum began at around that time. The He II 4686A line first appeared between days 7 and 14 and initially displayed a broad, symmetric profile that is characteristic of all species before day 60. Low-excitation lines remained comparatively narrow, with v(rad,max) of order 200-400 km/s. They were systematically more symmetric than lines such as [Ca V], [Fe VII], [Fe X], and He II, all of which showed a sequence of profile changes going from symmetric to a blue wing similar to that of the low ionization species but with a red wing extended to as high as 600 km/s . The Na I D doublet developed a broad component with similar velocity width to the other low-ionization species. The O VI Raman features were not detected. We interpret these variations as aspherical expansion of the ejecta within the Mira wind. The blue side is from the shock penetrating into the wind while the red wing is from the low-density periphery. The maximum radial velocities obey power laws, v(rad,max) t^{-n} with n ~ 1/3 for red wing and ~0.8 for the blue. (truncated)Comment: Accepted for publication, A&A (submitted: 9 Oct 2010; accepted: 1 Dec 2010) in press; based on data obtained with Swift, Nordic Optical Telescope, Ondrejov Observatory. Corrected typo, Fermi?LAT detection was at energies above 100 MeV (with thanks to C. C. Cheung

Moral Intuitions about Fault, Parenting, and Child Custody after Divorce

Allocations of child custody postdivorce are currently determined according to the best interest standard; that is, what is best for the child. Decisions about what is best for a child necessarily reflect cultural norms, at least in part. It is therefore useful as well as interesting to ask whether current understandings of the best interest standard align with moral intuitions of lay citizens asked to take the role of judge in hypothetical cases. Do factors such as whether 1 parent had an extramarital affair influence how respondents would award custody? In the current studies, a representative sample of citizens awaiting jury service was first given a neutral scenario portraying an “average” family. Almost 80% favored dividing custodial time equally between the 2 parents, replicating earlier findings. Then, in Study 1, they were given a second, test case, vignette in which either the mother or the father was said to have carried on an extramarital affair that “essentially ruined the marriage.” In Study 2, either the mother or the father was said to have sought the divorce, opposed by the other, simply because he or she “grew tired” of the marriage. For both test cases, our respondents awarded the offending parent significantly less parenting time; about half of our respondents in each Study. The findings indicate that many citizens feel both having an affair and growing tired of the marriage is sufficient cause to award decreased parenting time, reasons for which are explored in the discussion

Lay Judgments about Child Custody after Divorce

In a pair of studies, we examine lay people’s judgments about how hypothetical cases involving child custody after divorce should be resolved. The respondents were citizens called to jury service in Pima County, Arizona. Study 1 found that both male and female respondents, if they were the judge, would most commonly award equally shared custody arrangements, as advocated by most fathers’ groups. However, if the predivorce child care had been divided disproportionately between the parents, this preference shifted, slightly but significantly, toward giving more time to the parent who had provided most of that care, consistent with the Approximation Rule advocated by the American Law Institute. Moreover, respondents judged that the arrangements prevailing in today’s court and legal environment would award equal custody considerably less often, and would thereby provide much less parenting time to fathers, than the respondents themselves would award. Study 2 found that respondents maintained their strong preference for equally shared custody even when there are very high levels of parental conflict for which the parents were equally to blame, but awarded substantially less time to the culpable parent when only one was the primary instigator of the parental conflict. The striking degree to which the public favors equal custody combined with their view that the current court system under-awards parenting time to fathers could account for past findings that the system is seriously slanted toward mothers, and suggests that family law may have a public relations problem

Weak wind effects in CNO driven winds of hot first stars

During the evolution of rotating first stars, which initially consisted of only hydrogen and helium, CNO elements may emerge to their surface. These stars may therefore have winds that are driven only by CNO elements. We study weak wind effects (Gayley-Owocki heating and multicomponent effects) in stellar winds of first generation stars driven purely by CNO elements. We apply our NLTE multicomponent models and hydrodynamical simulations. The multicomponent effects (frictional heating and decoupling) are important particularly for low metallicity winds, but they influence mass loss rate only if they cause decoupling for velocities lower than the escape velocity. The multicomponent effects also modify the feedback from first stars. As a result of the decoupling of radiatively accelerated metals from hydrogen and helium, the first low-energy cosmic ray particles are generated. We study the interaction of these particles with the interstellar medium concluding that these particles easily penetrate the interstellar medium of a given minihalo. We discuss the charging of the first stars by means of their winds. Gayley-Owocki heating, frictional heating, and the decoupling of wind components occur in the winds of evolved low-metallicity stars and the solar metallicity main-sequence stars.Comment: 10 pages, accepted for publication in Astronomy & Astrophysic

Influence of the velocity gradient on the line formation in discs of cataclysmic variables

Context. The velocity field gradient in the radiative transfer in disc models of cataclysmic variables (CVs) is usually neglected; however, the geometry of the system and the value of Keplerian velocity suggest that it can be important for high inclination angles. Aims. We investigate the influence of the Keplerian velocity gradient on the line formation in CV discs. Methods. The vertical structure of the disc was determined using the NLTE accretion disc code AcDc, where the hydrostatic equation, the energy balance equation, the radiative transfer equation, the rate equations, and the equations of charge and particle conservation are consistently solved using the accelerated lambda iteration. NLTE opacities and emissivities are interpolated onto a 2D grid, where the radiative transfer equation was then solved with the velocity field taken into account. Results. We show line-profile changes and limb-darkening dependences for the Hα and Hγ lines in a model of SS Cyg, along with the HeI 4923 A° line of a model representing a typical AM CVn system. Both systems are considered in the quiescent phase. Conclusions. The line-profile changes due to the velocity gradient in the disc are small enough for most CV discs to allow the classical approach, where the radiative transfer is solved through the static disc and the velocity field is only taken into account in the final flux integration. However, the exact solution must be performed for CVs, where the disc rim plays an important role (inclination angles almost 90°). Extremely cool and relatively transparent discs under high inclinations should also be investigated with detailed radiative transfer models. © 2011 ESO

A hydrodynamic scheme for two-component winds from hot stars

We have developed a time-dependent two-component hydrodynamics code to simulate radiatively-driven stellar winds from hot stars. We use a time-explicit van Leer scheme to solve the hydrodynamic equations of a two-component stellar wind. Dynamical friction due to Coulomb collisions between the passive bulk plasma and the line-scattering ions is treated by a time-implicit, semi-analytic method using a polynomial fit to the Chandrasekhar function. This gives stable results despite the stiffness of the problem. This method was applied to model stars with winds that are both poorly and well-coupled. While for the former case we reproduce the mCAK solution, for the latter case our solution leads to wind decoupling.Comment: accepted to Astronomy and Astrophysic