55 research outputs found
The 2003-4 multisite photometric campaign for the Beta Cephei and eclipsing star 16 (EN) Lacertae with an Appendix on 2 Andromedae, the variable comparison star
A multisite photometric campaign for the Beta Cephei and eclipsing variable
16 Lacertae is reported. 749 h of high-quality differential photoelectric
Stromgren, Johnson and Geneva time-series photometry were obtained with ten
telescopes during 185 nights. After removing the pulsation contribution, an
attempt was made to solve the resulting eclipse light curve by means of the
computer program EBOP. Although a unique solution was not obtained, the range
of solutions could be constrained by comparing computed positions of the
secondary component in the Hertzsprung-Russell diagram with evolutionary
tracks.
For three high-amplitude pulsation modes, the uvy and the Geneva UBG
amplitude ratios are derived and compared with the theoretical ones for
spherical-harmonic degrees l <= 4. The highest degree, l = 4, is shown to be
incompatible with the observations. One mode is found to be radial, one is l =
1, while in the remaining case l = 2 or 3.
The present multisite observations are combined with the archival photometry
in order to investigate the long-term variation of the amplitudes and phases of
the three high-amplitude pulsation modes. The radial mode shows a
non-sinusoidal variation on a time-scale of 73 yr. The l = 1 mode is a triplet
with unequal frequency spacing, giving rise to two beat-periods, 720.7 d and
29.1 yr. The amplitude and phase of the l = 2 or 3 mode vary on time-scales of
380.5 d and 43 yr.
The light variation of 2 And, one of the comparison stars, is discussed in
the Appendix.Comment: 18 pages, 19 figures, accepted for publication in MNRA
Asteroseismology of the Beta Cephei star 12 (DD) Lacertae: photometric observations, pulsational frequency analysis and mode identification
We report a multisite photometric campaign for the Beta Cephei star 12
Lacertae. 750 hours of high-quality differential photoelectric Stromgren,
Johnson and Geneva time-series photometry were obtained with 9 telescopes
during 190 nights. Our frequency analysis results in the detection of 23
sinusoidal signals in the light curves. Eleven of those correspond to
independent pulsation modes, and the remainder are combination frequencies. We
find some slow aperiodic variability such as that seemingly present in several
Beta Cephei stars. We perform mode identification from our colour photometry,
derive the spherical degree l for the five strongest modes unambiguously and
provide constraints on l for the weaker modes. We find a mixture of modes of 0
<= l <= 4. In particular, we prove that the previously suspected rotationally
split triplet within the modes of 12 Lac consists of modes of different l;
their equal frequency splitting must thus be accidental.
One of the periodic signals we detected in the light curves is argued to be a
linearly stable mode excited to visible amplitude by nonlinear mode coupling
via a 2:1 resonance. We also find a low-frequency signal in the light
variations whose physical nature is unclear; it could be a parent or daughter
mode resonantly coupled. The remaining combination frequencies are consistent
with simple light-curve distortions.
The range of excited pulsation frequencies of 12 Lac may be sufficiently
large that it cannot be reproduced by standard models. We suspect that the star
has a larger metal abundance in the pulsational driving zone, a hypothesis also
capable of explaining the presence of Beta Cephei stars in the LMC.Comment: 12 pages, 7 figures, MNRAS, in pres
Photometry of ET Andromedae and pulsation of HD 219891
ET And is a binary system with a B9p(Si) star as the main component. We report on the photometric observing campaigns in 1988, 1989 and 1994 which confirmed the rotation period of 1(.)(d)618875 for ET And while refuting other published values. Furthermore, the controversial issue of pulsational stability of ET And is resolved since we have discovered pulsation for HD 219891, which was the main comparison star and sometimes exclusively used. The frequency of 10.0816 d(-1), a semi-amplitude of 2.5 mmag, T(eff) and M(v) suggest this comparison star to be a delta Scuti variable close to the blue border of the instability strip. The pulsational stability of ET And could be clearly established and hence no need exists to derive new driving mechanisms for stars between the classical instability strip and the region of slowly pulsating B-type (SPB) stars
A search for periodic and quasi-periodic photometric behavior in the cataclysmic variable TT arietis
Observations of TT Ari obtained at 11 observatories (campaign TT Ari-94) during 258 hr were carried out to study optical variability on timescales from minutes to weeks. The best-fit primary photometric period determined from 16 nights of data obtained at the Dushak-Eregdag station of the Odessa State University is P = 0d.133160 Β± 0d.000004 with a mean amplitude of 0.0513 Β± 0.0008 mag. This new primary photometric period is larger than that obtained during the TT Ari-88 campaign and is well outside the range of estimates published since 1961. Contrary to previous findings, the "5-7 hr" secondary photometric period is not seen. Our observations do show evidence for periods of 2d.916 and 0d.3040 with amplitudes of 43 and 25 mmag, respectively. The beat period between the spectroscopic and photometric periods is not seen. No coherent oscillations in the range f = 10-2500 cycles day-1 are found. The highest peaks in the power spectrum cover the wide range of 24-139 cycles day-1. In the mean periodogram, the highest peak corresponds to 21 and 30 minutes for the largest sets of observations, i.e., those obtained at Odessa and Krakow Universities, respectively. In the instrumental B system, variations with an amplitude exceeding 0.011 mag occur 8 times (from 33 runs) at 24 minutes. We conclude that quasi-periodic variations occur at a few preferred timescales rather than at a relatively stable period with a secular decrease. In the frequency range 90-900 cycles day-1, the power spectrum obeys a power law with a slope ranging from Ξ³ = 1.3 to 2.6 for different runs
DIGITAL ECONOMY FOR EXPORT: DEVELOPMENT OF COMPETENCIES AND SUPPORT TOOLS
The authors examined key theoretical and practical aspects of the process of development and implementation of electronic commerce of Russian enterprises. Based on the analysis of existing forms of state support, as well as a statistical review of the current domestic Russian situation, the main problems and determinants that determine the low level of technological development and export of enterprises through marketplaces are identified. Recommendations on improving the system and developing digital export competencies are formulated.ΠΠ²ΡΠΎΡΠ°ΠΌΠΈ ΡΠ°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ ΠΊΠ»ΡΡΠ΅Π²ΡΠ΅ ΡΠ΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΈ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ Π°ΡΠΏΠ΅ΠΊΡΡ ΠΏΡΠΎΡΠ΅ΡΡΠ° ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΈ ΡΠ΅Π°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΡΠΈΡΡΠΎΠ²ΠΎΠ³ΠΎ ΡΠΊΡΠΏΠΎΡΡΠ° ΠΈ ΡΠ»Π΅ΠΊΡΡΠΎΠ½Π½ΠΎΠΉ ΠΊΠΎΠΌΠΌΠ΅ΡΡΠΈΠΈ Π² Ρ
ΠΎΠ·ΡΠΉΡΡΠ²Π΅Π½Π½ΠΎΠΉ ΠΆΠΈΠ·Π½ΠΈ ΡΠΎΡΡΠΈΠΉΡΠΊΠΈΡ
ΠΏΡΠ΅Π΄ΠΏΡΠΈΡΡΠΈΠΉ. ΠΠ° ΠΎΡΠ½ΠΎΠ²Π΅ Π°Π½Π°Π»ΠΈΠ·Π° ΡΡΡΠ΅ΡΡΠ²ΡΡΡΠΈΡ
ΡΠΎΡΠΌ Π³ΠΎΡΡΠ΄Π°ΡΡΡΠ²Π΅Π½Π½ΠΎΠΉ ΠΏΠΎΠ΄Π΄Π΅ΡΠΆΠΊΠΈ, Π° ΡΠ°ΠΊΠΆΠ΅ ΡΡΠ°ΡΠΈΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΎΠ±Π·ΠΎΡΠ° ΠΌΠ΅ΠΆΠ΄ΡΠ½Π°ΡΠΎΠ΄Π½ΠΎΠΉ ΠΈ Π²Π½ΡΡΡΠΈΡΠΎΡΡΠΈΠΉΡΠΊΠΎΠΉ ΠΊΠΎΠ½ΡΡΠ½ΠΊΡΡΡΡ ΠΎΠ±ΠΎΠ·Π½Π°ΡΠ΅Π½Ρ ΠΎΡΠ½ΠΎΠ²Π½ΡΠ΅ ΠΏΡΠΎΠ±Π»Π΅ΠΌΡ ΠΈ Π΄Π΅ΡΠ΅ΡΠΌΠΈΠ½Π°Π½ΡΡ, ΠΎΠ±ΡΡΠ»Π°Π²Π»ΠΈΠ²Π°ΡΡΠΈΠ΅ Π½Π΅Π²ΡΡΠΎΠΊΠΈΠΉ ΡΡΠΎΠ²Π΅Π½Ρ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ°Π·Π²ΠΈΡΠΈΡ. Π‘ΡΠΎΡΠΌΡΠ»ΠΈΡΠΎΠ²Π°Π½Ρ ΡΠ΅ΠΊΠΎΠΌΠ΅Π½Π΄Π°ΡΠΈΠΈ ΠΏΠΎ ΡΠΎΠ²Π΅ΡΡΠ΅Π½ΡΡΠ²ΠΎΠ²Π°Π½ΠΈΡ ΡΠΈΡΡΠ΅ΠΌΡ ΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΡΠΈΡΡΠΎΠ²ΡΡ
ΡΠΊΡΠΏΠΎΡΡΠ½ΡΡ
ΠΊΠΎΠΌΠΏΠ΅ΡΠ΅Π½ΡΠΈΠΉ.ΠΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ ΡΡΠ°ΡΡΠΈ ΠΏΠΎΠ΄Π³ΠΎΡΠΎΠ²Π»Π΅Π½Ρ Π°Π²ΡΠΎΡΠ°ΠΌΠΈ ΠΏΡΠΈ ΠΏΠΎΠ΄Π΄Π΅ΡΠΆΠΊΠ΅ Π³ΡΠ°Π½ΡΠ° Π Π€Π€Π β 19-29-07131
Identification of territorial industrial clusters of Russian economy in view of their involvement into the development of the state innovation policy
The article is devoted to the important role of clusters in the innovative development of the economy. The results of the activities of 25 pilot innovative territorial cluster-leaders of the Russian Federation in terms of investment potential in 2012-2018 were estimated. Method of identification of the innovative territorial clusters was suggested , its main advantages being universalism, comprehensiveness and credibilit
Chemistry for Sustainable Development 18 (2010) 315319 Low-Temperature Fusion and Autoclave Processes for Decomposing Ores and Precious Metal Concentrates
Abstract Features of opening resistant materials in the open and closed systems are considered. A possibility is demonstrated for increasing the decomposition efficiency concerning refractory ores and precious metal concentrates in open systems with the application of low-temperature alkali fusion and acidic oxidative opening in closed systems such as autoclaves with the use of microwave radiation
Spectral manifestations of intramolecular interactions in acid chlorides of unsaturated acids of phosphorus
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