265 research outputs found
Optical observations of "hot" novae returning to quiescence
We have monitored the return to quiescence of novae previously observed in
outburst as supersoft X-ray sources, with optical photometry of the
intermediate polar (IP) V4743 Sgr and candidate IP V2491 Cyg, and optical
spectroscopy of these two and seven other systems. Our sample includes
classical and recurrent novae, short period (few hours), intermediate period
(1-2 days) and long period (symbiotic) binaries. The light curves of V4743 Sgr
and V2491 Cyg present clear periodic modulations. For V4743 Sgr, the modulation
occurs with the beat of the rotational and orbital periods. If the period
measured for V2491 Cyg is also the beat of these two periods, the orbital one
should be almost 17 hours. The recurrent nova T Pyx already shows fragmentation
of the nebular shell less than 3 years after the outburst. While this nova
still had strong [OIII] at this post-outburst epoch, these lines had already
faded after 3 to 7 years in all the others. We did not find any difference in
the ratio of equivalent widths of high ionization/excitation lines to that of
the Hbeta line in novae with short and long orbital period, indicating that
irradiation does not trigger high mass transfer rate from secondaries with
small orbital separation. An important difference between the spectra of RS Oph
and V3890 Sgr and those of many symbiotic persistent supersoft sources is the
absence of forbidden coronal lines. With the X-rays turn-off, we interpret this
as an indication that mass transfer in symbiotics recurrent novae is
intermittent.Comment: In press in Monthly Notices of the Royal Astronomical Societ
Two New LBV Candidates in the M33 Galaxy
We present two new luminous blue variable (LBV) candidate stars discovered in
the M33 galaxy. We identified these stars (Valeev et al. 2010) as massive star
candidates at the final stages of evolution, presumably with a notable
interstellar extinction. The candidates were selected from the Massey et al.
(2006) catalog based on the following criteria: emission in Halpha, V<18.5 and
0.35<(B-V)<1.2. The spectra of both stars reveal a broad and strong Halpha
emission with extended wings (770 and 1000 km/s). Based on the spectra we
estimated the main parameters of the stars. Object N45901 has a bolometric
luminosity log(L/Lsun)=6.0-6.2 with the value of interstellar extinction
Av=2.3+-0.1. The temperature of the star's photosphere is estimated as
Tstar~13000-15000K its probable mass on the Zero Age Main Sequence is
M~60-80Msun. The infrared excess in N45901 corresponds to the emission of warm
dust with the temperature Twarm~1000K, and amounts to 0.1% of the bolometric
luminosity. A comparison of stellar magnitude estimates from different catalogs
points to the probable variability of the object N45901. Bolometric luminosity
of the second object, N125093, is log(L/Lsun)=6.3-6.6, the value of
interstellar extinction is Av=2.75+-0.15. We estimate its photosphere's
temperature as Tstar~13000-16000K, the initial mass as M~90-120Msun. The
infrared excess in N125093 amounts to 5-6% of the bolometric luminosity. Its
spectral energy distribution reveals two thermal components with the
temperatures Twarm~1000K and Tcold~480K. The [CaII] lines (7291A and 7323A),
observed in LBV-like stars VarA and N93351 in M33, are also present in the
spectrum of N125093. These lines indicate relatively recent gas eruptions and
dust activity linked with them. High bolometric luminosity of these stars and
broad Halpha emissions allow classifying the studied objects as LBV candidates.Comment: 14 pages, 4 figure
Relationships among curricular and extra-curricular activities and fundamental competencies for working persons
Two kinds of data analysis methods were applied to the retrospective survey data collected by Morita, Shimizu, and Funaba (2012) to determine which university education programs and activities influence the alumni’s job performance. The result by correspondence analysis among university programs and activities and the fundamental competencies for working persons defined by the Japanese Ministry of Economy, Trade and Industry (2007) indicated the following four clusters: (1) seminar and one’s ability to deliver opinions clearly, to analyze the status quo, and to clarify issues; (2) curriculum and one’s foreign language ability; (3) extra-curricular activities and one’s ability to listen carefully to others’ opinions and to influence and involve others; and (4) one’s activities outside university and the ability to create new values. The causal relationships among the actual degrees of curricular and extra-curricular activities in university, the utility of such activities in university life, and the three factors extracted from the responses to the questions of the fundamental competencies were also analyzed by the path analysis method. Activities outside university affected most significantly the alumni’s ability to solve issues, while a few activitiesrelated to university life affected their ability to collaborate with various people and to manage stress. The methodological issues with the alumni survey were also discussed along with the implications of these findings.大学における教育プログラムと活動が,卒業生の仕事の遂行に与える影響について明らかにするために,森田・清水・船場(2011)によって収集された回想的調査データに2 種類の分析方法論を適用した。経済産業省(2007)によって定義された社会人基礎力と大学におけるプログラム,活動の関係についての対応分析による結果から,以下の4クラスタが得られた:⑴ゼミと自分の意見を分かりやすく伝える力,現状を分析し課題を明らかにする力,⑵講義と語学力,⑶正課外活動と相手の意見を丁寧に聴く力,他人に働きかけ巻き込む力,そして,⑷学外での活動と新しい価値を生み出す力,である。大学の正課・正課外活動,大学生活における幾つかの活動の有用性,そして基礎能力についての質問項目から抽出された3つの因子の因果関係について,パス解析による分析を行った。学外での活動は,課題解決力に対して最も有意に影響していた。大学生活における少数の活動が対人関係力,ストレス耐性力に影響していた。卒業生調査における方法論的問題とこれらの知見について考察を行った
Magnetic and Mössbauer effect studies of ZnO thin film implanted with iron ions to high fluence
© Published under licence by IOP Publishing Ltd.We present the results of magnetic and Mössbauer effect studies of zinc oxide thin film obtained by RF magnetron sputtering and implanted with 40 keV iron ions to a fluence of 1.5•1017 ion/cm2. As-implanted and post-annealed sample shows ferromagnetic properties at room temperature and consists of paramagnetic and ferromagnetic phases according to Mössbauer spectroscopy
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