149 research outputs found
V1135 Herculis: a double-lined eclipsing binary with an Anomalous Cepheid
BVR light curves and radial velocities for the double-lined eclipsing binary
V1135\,Her were obtained. The brighter component of V1135\,Her is a Cepheid
variable with a pulsation period of 4.224330.00026 days. The orbital
period of the system is about 39.997820.00233 days, which is the shortest
value among the known Type\,II Cepheid binaries. The observed B, V, and R
magnitudes were cleaned for the intrinsic variations of the primary star. The
remaining light curves, consisting of eclipses and proximity effects, are
obtained. Our analyses of the multi-colour light curves and radial velocities
led to the determination of fundamental stellar properties of both components
of the interesting system V1135\,Her. The system consists of two evolved stars,
G1+K3 between giants and supergiants, with masses of M=1.4610.054
\Msun ~and M=0.5040.040 {\Msun} and radii of R=27.10.4
{\Rsun} and R=10.40.2 {\Rsun}. The pulsating star is almost filling
its corresponding Roche lobe which indicates the possibility of mass loss or
transfer having taken place. We find an average distance of d=7500450 pc
using the BVR magnitudes and also the V-band extinction. Location in the Galaxy
and the distance to the galactic plane with an amount of 1300 pc indicate that
it probably belongs to the thick-disk population. Most of the observed and
calculated parameters of the V1135\,Her and its location on the color-magnitude
and period-luminosity diagrams lead to a classification of an Anomalous
Cepheid.Comment: 25 pages, 9 Tables, 9 Figures, Accepted Revista Mexicana de
Astronom\'ia y Astrof\'isica. arXiv admin note: substantial text overlap with
arXiv:1211.120
The multiperiodicity of the Doradus stars HD 224945 and HD 224638 as detected from a multisite campaign
We discuss new photometric data collected on the gamma Dor variables HD
224945 and HD 224638. Multiperiodicity was detected in both stars, thanks to
the clear spectral window of a multisite campaign that involved five
observatories. HD 224945 shows the shortest period among the gamma Dor stars,
i.e., 0.3330 d. The pulsation behaviour is very different: HD 224945 displays a
set of frequencies spread over an interval much wider than that of HD 224638.
We clearly found evidence for amplitude variations in the excited modes by
comparing data from different years. HD 224945 and HD 224638 are among the best
examples of Dor stars that show multimode pulsations, which make them
very interesting from an asteroseismological point of view.Comment: 8 pages (in A&A style), 3 eps figures. Accepted for A&A Main Journa
Orbital period changes and the higher-order multiplicity fraction amongst SuperWASP eclipsing binaries
Orbital period changes of binary stars may be caused by the presence of a third massive body in the system. Here we have searched the archive of the Wide Angle Search for Planets (SuperWASP) project for evidence of period variations in 13 927 eclipsing binary candidates. Sinusoidal period changes, strongly suggestive of third bodies, were detected in 2% of cases; however, linear period changes were observed in a further 22% of systems. We argue on distributional grounds that the majority of these apparently linear changes are likely to reflect longer-term sinusoidal period variations caused by third bodies, and thus estimate a higher-order multiplicity fraction of 24% for SuperWASP binaries, in good agreement with other recent figures for the fraction of triple systems amongst binary stars in general
Effect of egg white protein-pectin electrostatic interactions in a high sugar content system on foaming and foam rheological properties
The aim of this study was to evaluate the effect of electrostatic interaction between egg white protein (EW) and pectin in a high sugar content system (80 wt% total solid) on the foaming properties (density, overrun and stability) and foam rheological properties. A central composite rotatable design was carried out to study the effects of biopolymer concentration (1.40-5.60%, w/w) and EW:pectin ratio (7:1-63:1) on the apparent viscosity before whipping, foaming capacity (density and overrun) and foam rheological properties (storage modulus G', loss modulus G" and phase angle δ) of sugar/EW/pectin mixtures at pH 3.0. The apparent viscosity increased as biopolymer concentration increased while EW:pectin ratio had no significant effect (p>0.10) on this response. At 7:1 EW:pectin ratio, the mixture presented low foaming capacity, resulting in foam with less solid character and low stability, possibly due to the pectin excess in the system. At 49:1 EW:pectin ratio, the mixture showed higher foaming capacity and foam elasticity. The formation of soluble complexes between EW and pectin possibly increased the continuous phase viscosity and enhanced the foam stability by slowing liquid drainage
Multimode Pulsations of the λ Bootis Star 29 Cygni: The 1995 and 1996 Multisite Campaigns
In this paper we present the results of multisite photometric and spectroscopic campaigns, carried out during the years 1995 and 1996, to study the pulsations of a typical λ Bootis star, 29 Cyg. During the 1995 campaign we found well-defined multiperiodicity in 29 Cyg, which was studied in detail during a multilongitude campaign covering a 65 day time interval in 1996. The frequency analysis of the 1996 campaign's data easily revealed 11 excited low ℓ degree modes with frequencies of oscillation ranging from 20.3 to 37.4 cycles day-1 and mean photometric amplitudes ranging from 10.65 to 0.96 mmag in the V filter. After removing the well-identified frequencies, the discrete Fourier transform of the residuals showed excess power in the 20-40 cycle day-1 domain, which indicates the probable existence of unresolved rich p-mode spectra with photometric V amplitudes below 0.5 mmag. We found a regular spacing of 2.41 cycles day-1 within the modes of 29 Cyg, which was interpreted as the spacing of consecutive even and odd ℓ-values. The asteroseismic luminosity log L/L⊙ = 1.12, calculated from the frequency spacing, is in good agreement with the Hipparcos luminosity log L/L⊙ = 1.16 and with luminosities from photometric and spectroscopic calibrations. Using our multicolor photometry we tentatively identified the dominant f1 = 37.425 cycle day -1 mode as an ℓ= 2, n = 5 mode, and made radial overtone identification for all frequencies. These ranged from n = 2 to 5. Analysis of the photometric data shows the long-term (years) and probable short-term (days) variability of amplitudes for all of these modes in 29 Cyg. Using our multicolor WBVR filter photometry, we found the wavelength dependence of the pulsation amplitudes for the five highest amplitude modes. Based on the Hα line radial velocity observations of 29 Cyg, we detected multiperiodic radial velocity variations with frequencies of 38.36 and 29.99 cycles day-1 and semiamplitudes of 1.0 and 0.8 km s-1, respectively. These frequencies coincide within the errors with the photometric frequencies of the two highest amplitude modes, 37.425 and 29.775 cycles day-1. For the highest amplitude ℓ = 2, n = 5 mode (37.425 cycles day-1), the radial velocity-to-light amplitude ratio and velocity-to-light phase shift are equal to 2K(Hα)/ Δ V = 94 km mag-1 s-1 and Φf1 = φVr - φV = +0.08 ± 0.01, respectively, and are in good agreement with values for δ Scuti stars. The rich multiperiodic spectrum makes 29 Cyg a promising target for future multisite campaigns. © 2007. The American Astronomical Society. All rights reserved.M. D. E. and K. Y. W. acknowledge their work as part of the research activity of the Astrophysical Research Center for the Structure and Evolution of the Cosmos, which is supported by
the Korean Science and Engineering Foundation. The participation of G. H., E. P., and W. W. was supported by the Austrian Fonds zur Förderung der wissenschaftlichen Forschung under
grant S-7303. The spectroscopic observations described in this publication were made possible in part by grants R2Q000 and U1C000 from the International Science Foundation and by grant
A-05-067 from the ESO C&EE programme. This work was supported in part by US Civilian and Research Development Foundation grant UP2-317.Peer reviewe
An investigation into the properties of tarhana produced by traditional and extrusion methods
SIGLEAvailable from British Library Document Supply Centre-DSC:DXN004761 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Chemical and structural variations in hazelnut and soybean oils after ozone treatments
In the present work, the effect of ozone treatments on the structural properties of soybean oil (SBO) and hazelnut oil (HO) were investigated. The study presents the findings and results about the oxidation of HO and SBO with ozone, which has not been fully studied previously. The HO and SBO were treated with ozone gas for 1, 5, 15, 30, 60, 180 and 360 min. The ozone reactivity with the SBO and HO during the ozone treatment was analyzed by 1H, 13C NMR, FTIR and GC. The iodine value, viscosity and color variables (L*, a* and b*) of untreated and ozone treated oils were determined. Reaction products were identified according to the Criegee mechanism. New signals at 5.15 and 104.35 ppm were assigned to the ring protons of 1,2,4- trioxolane (secondary ozonide) in the ozonated oils in 1H and 13C NMR, respectively. Ozonated oils exhibited peaks at 9.75 and 2.43 ppm in 1H and NMR, which corresponded to the aldehydic proton and α-methylene group and to the carbonyl carbon, respectively. The peak at 43.9 ppm in 13C NMR was related to the α-methylene group and to the carbonyl carbon. The new signals formed in the ozonation process gradually increased with respect to ozone treatment time. After 360 min of ozone treatment, the carbon-carbon double bond signal, which belongs to the unsaturated fatty acids, disappeared completely in the spectrum. An increase in viscosity, a decrease in iodine value and a dramatic reduction in b* of the oil samples on (+) axis were observed with increased ozone treatment time
Light curve variations in ER vulpeculae
Photoelectric observations of the peculiar eclipsing variable ER Vul were obtained in blue and yellow light, in the 1981 and 1982 observing seasons. The light curves suffer to change in short time-intervals. The wave-like distortion superimposed on the light curves is clearly seen, but sometimes there is no indication about its existence. The migration period has been estimated roughtly about eight months. Moreover, small-amplitude light fluctuations in the light curves are noticeable. These variations seem to be occur randomly. When the IUE and optical observations are taken into consideration together it is strongly suggested that both of the components in the system ER Vul are too active. © 1987 D. Reidel Publishing Company
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