High-precision elements of double-lined spectroscopic binaries from combined interferometry and spectroscopy. Application to the beta Cephei star beta Centauri

We present methodology to derive high-precision estimates of the fundamental parameters of double-lined spectroscopic binaries. We apply the methods to the case study of the double-lined beta Cephei star beta Centauri. We also present a detailed analysis of beta Centauri's line-profile variations caused by its oscillations. We point out that a systematic error in the orbital amplitudes, and any quantities derived from them, occurs if the radial velocities of blended component lines are computed without spectral disentangling. This technique is an essential ingredient in the derivation of the physical parameters if the goal is to obtain a precision of only a few percent. We have devised iteration schemes to obtain the orbital elements for systems whose lines are blended throughout the orbital cycle. We find the following parameters for beta Cen: $M_1=10.7\pm 0.1 M_\odot$ and $M_2=10.3\pm 0.1 M_\odot$, an age of $(14.1\pm 0.6)\times 10^6$ years. We deduce two oscillation frequencies for the broad-lined primary of beta Centauri with degrees higher than 2. We propose that our iteration schemes be used in any future derivations of the spectroscopic orbital parameters of double-lined binaries with blended component lines to which disentangling can be successfully applied.Comment: 12 pages, 13 figures, accepted for publication in A&

Interpretation of the variability of the <i>β</i> Cephei star <i>λ</i> Scorpii. I. The multiple character

We derive accurate values of the orbital parameters of the close binary β Cephei star λ Scorpii. Moreover, we present the first determination of the properties of the triple system to which λ Scorpii belongs. Our analysis is based on a time series of 815 high-resolution spectra, covering a timespan of 14 years. We find a close orbit of 5d.9525days (e=0.26) and a wide orbit of approximately 1082d days (e=0.23). The orbital parameters of the triple star and a spectrum synthesis lead us to conclude that the system is composed of two early-type B stars and a low-mass pre-main-sequence star rather than containing an ultra-massive white dwarf as claimed before. Our proposed configuration is compatible with population synthesis. The radial velocity variations of the primary allow us to confirm the presence of at least one pulsation mode with frequency 4.679410 c d-1 which is subject to the light-time effect in the triple system. A detailed analysis of the complex line-profile variations is described in a subsequent paper

A Grid of FASTWIND NLTE Model Atmospheres of Massive Stars

In the last few years our knowledge of the physics of massive stars has improved tremendously. However, further investigations are still needed, especially regarding accurate calibrations of their fundamental parameters. To this end, we have constructed a comprehensive grid of NLTE model atmospheres and corresponding synthetic spectra in the massive star domain. The grid covers the complete B type spectral range, extended to late O on the hot side and early A on the cool side, from supergiants to dwarfs and from weak stellar winds to very strong ones. It has been calculated with the latest version of the FASTWIND code. The analysis of an extensive sample of OB stars in the framework of the COROT space mission will lead to accurate calibrations of effective temperatures, gravities, mass loss rates etc. This paper contains a detailed description of the grid, which has been baptised as BSTAR06 and which will be available for further research in the near future.Comment: 9 pages, 17 figures, to be published in ASP Conference Series, Proceeding of the Standardisation Workshop, held in Blankenberge on 8-11 Ma

Regression Models for Strength Assessment Method Selection and Performance Predictions

Please view abstract in the attached PDF file

Polish and Icelandic vocabulary of Polish preschool children in Iceland: characteristics of the preschool and home language environment of bilingual children

Máltaka tvítyngdra barna dreifist á tvö tungumál og það hversu hratt og vel þau ná tökum á málunum er meðal annars háð því ílagi sem þau fá í hvoru tungumáli fyrir sig. Rannsóknir á orðaforða tvítyngdra barna sem alast upp á Íslandi sýna að íslenskur orðaforði þeirra er mun minni en orðaforði eintyngdra jafnaldra þeirra, en minna er vitað um stöðu þeirra í sínu móðurmáli. Viðfangsefni þessarar rannsóknar var að kanna pólskan og íslenskan orðaforða tvítyngdra barna og skoða hvernig málumhverfi barnanna heima og í leikskóla styður máltöku beggja málanna. Þátttakendur voru fjórtán börn á aldrinum 4–6 ára sem eiga pólska foreldra en hafa alist upp á Íslandi frá fæðingu eða frumbernsku. Orðaforði barnanna var metinn með íslensku og pólsku orðaforðaprófi, foreldrar þeirra svöruðu spurningalista um málumhverfi heima fyrir og tekin voru viðtöl við deildarstjóra í leikskólum barnanna. Meginniðurstöður voru þær að pólskur orðaforði flestra barnanna var innan viðmiðunarmarka fyrir eintyngd pólsk börn. Íslenskur orðaforði þeirra var hins vegar mun slakari en orðaforði eintyngdra íslenskra barna á sama aldri. Niðurstöður úr spurningakönnuninni sýndu að fyrir tveggja ára aldur höfðu öll börnin fyrst og fremst heyrt pólsku dagsdaglega en lítil kynni haft af íslensku. Foreldrar barnanna voru meðvitaðir um mikilvægi þess að börnin þeirra lærðu pólsku og hlúðu vel að máltöku hennar. Í leikskólunum var hins vegar lagt mest upp úr því að kenna börnunum íslensku en minni áhersla lögð á að styrkja pólskukunnáttu þeirra. Málörvun í leikskólunum fór mest fram í gegnum daglegt starf; leik, samræður, söng og lestur. Deildarstjórar töldu að flest þessara barna þyrftu á frekari málörvun að halda til að ná góðum tökum á íslensku og mörg þeirra fengu sérkennslu í einhverju formi. Í viðtölum við deildarstjóra kom hins vegar fram að þeir töldu ekki nóg að gert og kölluðu eftir auknum tíma til að sinna þessum þætti, sem og fræðslu og stuðningi við leikskólakennara.Bilingual language acquisition is a broad field and subject to many influencing factors. The rate and success of acquisition of two languages varies greatly with regard to the amount and type of input children receive in each language. Research studies on vocabulary knowledge of bilingual children in Iceland have shown that the Icelandic vocabulary of children of immigrant background is considerably smaller than that of their monolingual peers. However, less is known about their vocabulary knowledge in their mother tongue. The main aim of this study was to test the Polish and Icelandic vocabulary of bilingual children to assess their development in the two languages. In addition, the effect of the home and preschool language environment on children’s vocabulary development was investigated. The study was conducted in the autumn of 2014. The participants were 14 children, 4–6 years old (born 2009–2010), who were born in Iceland and whose parents’ native language was Polish. The children were chosen from six preschools located in southwest Iceland, outside Reykjavík. Six of the participants attended one preschool, the remaining eight were distributed between five preschools. Two vocabulary measurements were used in the study: an Icelandic version of the Peabody Picture Vocabulary Test (PPVT-4) which has been translated/adapted and norm-referenced for four to eight-year-old Icelandic children and a standardized Polish vocabulary test, the Picture Vocabulary Test – Comprehension (OTSR) designed for use with children aged 2 to 6 years. A detailed questionnaire in Polish was given to the children’s parents to investigate the home language environment of the bilingual children. In addition, interviews were conducted with the heads of the eight preschool departments (in six preschools) attended by the participating children. The main results of the vocabulary tests showed that the receptive vocabulary in Polish of the majority of the children was similar in size to that of Polish monolingual children of the same age and gender. On the other hand, the size of their receptive vocabulary in Icelandic was found to be below the average for Icelandic monolingual children. The results suggest that although the participating children have lived in Iceland since infancy, their Icelandic vocabulary is weak. The main findings from the parent questionnaire showed that Polish was the primary language heard daily by all the children during the first two years of life and continued to be the main language used by the children for communication with parents, siblings and other adults. According to the department heads, the main emphasis of the preschool was to assist the bilingual children in learning Icelandic; learning the mother tongue was seen to be the responsibility of the parents. Similar language development practices were used in all the preschools. Language development was intertwined with daily activities and with pull-out lessons for literacy development. The main areas of emphasis mentioned by the department heads were reading to children and discussing the stories with them. The Text Talk method (Orðaspjall) was also used for vocabulary development. In four of the preschools the participating children received special lessons with emphasis on Icelandic vocabulary development. Parents of the bilingual children were generally happy with their cooperation with the preschools. The parents wanted to have positive relations and good communication with preschool staff, but sometimes they felt that communication was hampered by language difficulties. Likewise, the teachers experienced difficulties maintaining open and full communication with parents. They occasionally used interpreters for parent-teacher meetings, but this was not always possible. Finally, teachers used informal methods to assess the bilingual children’s language abilities and many felt the need for a vocabulary assessment tool which would assist teachers in addressing the vocabulary development needs of bilingual children at preschool. The department heads called for more support and training for staff in effective methods of language teaching in order to better meet the needs of the growing number of bilingual children in Icelandic preschools.Peer Reviewe

Analytics of crystal growth in space

The variation of radial impurity distribution induced by surface tension driven flow increases as the zone length decreases in silicon crystals grown by floating zone melting. In combined buoyancy driven and surface tension driven convection at the gravity of earth, the buoyancy contribution becomes relatively smaller as the zone diameter decreases and eventually convection is dominated by the surface tension driven flow (in the case of silicon, for zones of less than about 0.8 cm in diameter). Preliminary calculations for sapphire suggest the presence of an oscillatory surface tension driven convection as a result of an unstable melt surface temperature that results when the zone is heated by a radiation heater

Campus Vol IX N 3

Shaw, Ted. Cover. Picture. 1. Anonymous. The New Yahker . Prose. 7. Anonymous. Professor Biddleton\u27s Experiment . Prose. 6. Hoh, Paul. Good Night . Poem. 10. Kull, Shaw. Guilty . Cartoon. 11. Shaw, Ted. Untitled. Cartoon. 12. Jacobs, Wolcott. The Belle of Balu . Prose. 12. LeFever, Ogden Gnash. The Tragedy of Herman Gath . Prose. 14. Anonymous. Habitual . Prose. 16. Cook, Mike. This is Jazz . Prose. 17. Tuttle, C. Untitled. Cartoon. 16. Anonymous. More Books . Prose. 19

Space construction system analysis. Part 2: Construction analysis

The construction methods specific to the end to end construction process for building the ETVP in low Earth orbit, using the space shuttle orbiter as a construction base, are analyzed. The analyses concerned three missions required to build the basic platform. The first mission involved performing the fabrication of beams in space and assembling the beams into a basic structural framework. The second mission was to install the forward support structure and aft support structure, the forward assembly, and a TT&C antenna. The third mission plan was to complete the construction of the platform and activate it to begin operations in low Earth orbit. The integration of the activities for each mission is described along with the construction requirements and construction logic

Periodic mass loss episodes due to an oscillation mode with variable amplitude in the hot supergiant HD50064

We aim to interpret the photometric and spectroscopic variability of the luminous blue variable supergiant HD\,50064 ($V=8.21$).CoRoT space photometry and follow-up high-resolution spectroscopy, with a time base of 137\,d and 169\,d, respectively, was gathered, analysed and interpreted using standard time series analysis and light curve modelling methods as well as spectral line diagnostics.The space photometry reveals one period of 37\,d, which undergoes a sudden amplitude change with a factor 1.6. The pulsation period is confirmed in the spectroscopy, which additionally reveals metal line radial velocity values differing by $\sim 30\,$km\,s$^{-1}$ depending on the spectral line and on the epoch. We estimate \teff$\sim$13\,500\,K, \logg$\sim$1.5 from the equivalent width of Si lines. The Balmer lines reveal that the star undergoes episodes of changing mass loss on a time scale similar to the changes in the photometric and spectroscopic variability, with an average value of $\log\dot{\rm M}\simeq-5$ (in M$_\odot$\,yr$^{-1}$). We tentatively interpret the 37\,d period as due to a strange mode oscillation.Comment: 4 pages, accepted for publication in Astronomy & Astrophysics Letter