Search results for "Binary system"
showing 10 items of 95 documents
Chandra study of the eclipsing M dwarf binary, YY Gem
2012
The eclipsing M dwarf binary system, YY Gem, was observed using Chandra covering 140 ks (2Prot) in total, split into two even exposures separated by 0.76 d (0.94 Prot). The system was extremely active: three energetic flares were observed over the course of these observations. The flaring and non-flaring states of the system are analysed in this paper. The activity level increased between the first and second observations even during the quiescent (non-flaring) phases. An analysis of the dynamics of the X-ray-emitting plasma suggests that both components are significantly active. Contemporaneous Hα spectra also suggest that both components show similar levels of activity. The primary star i…
Unmixing of binary alloys by a vacancy mechanism of diffusion: a computer simulation
1991
The initial stages of phase separation are studied for a model binary alloy (AB) with pairwise interactions e AA , e AB , e BB between nearest neighbors, assuming that there is no direct interchange of neighboring atoms possible, but only an indirect one mediated by vacancies (V) occurring in the system at a concentrationc v and which are strictly conserved, as are the concentrationsc A andc B of the two species.A-atoms may jump to vacant sites with jump rateГ A , B-atoms with jump rateГ B (in the absence of interactions). Particular attention is paid to the question to what extent nonuniform distribution of vacancies affects the unmixing kinetics. Our study focuses on the special caseГ A =…
Absolute parameters for binary systems
1997
New high-quality light curves of the late-type binary system BH Vir have been obtained during a 6 year photometric uvby and monitoring program of low mass eclipsing binaries (Clement et al. 1997), hereafter Papers I and II. This paper presents detailed analysis of this binary based on the four light curves obtained within our program. The activity wave superimposed on the eclipse-modulated light curves has been adjusted and removed by using a new iterative application of the standard EBOP code together with truncated Fourier Series fittings. Combining the recent radial velocity curves (Popper 1995) with the geometrical elements deduced from the "clean" photometric light curves, the absolute…
Absolute parameters for binary systems
1997
New light curves of the late-type binary sys- tem ZZ UMa were obtained during a uvby and H mon- itoring program on low mass eclipsing binaries, that has been carried out in a six year photometric observational program (Clement et al. 1997a, Paper I). The main goal of the program is to obtain accurate absolute parameters for stars in the low and intermediate mass range, in order to improve the Mass-Luminosity Relationship (MLR) at the end of the main sequence. This paper presents a complete analysis of the rst uvby light curves of the late-type detached eclipsing binary ZZ UMa. This binary system has been observed during eight campaigns at the Calar Alto Observatory (Almeria, Spain). The act…
The H-graph with equal masses in terms of multiple polylogarithms
2021
The initial phase of the inspiral process of a binary system producing gravitational waves can be described by perturbation theory. At the third post-Minkowskian order a two-loop double box graph, known as H-graph contributes. We consider the case where the two objects making up the binary system have equal masses. We express all master integrals related to the equal-mass H-graph up to weight four in terms of multiple polylogarithms. We provide a numerical program which evaluates all master integrals up to weight four in the physical regions with arbitrary precision.
Disc loss and renewal in A0535+26
1999
This paper presents observations of the Be/X-ray binary system A0535+26 revealing the first observed loss of its circumstellar disc, demonstrated by the loss of its JHK infrared excess and optical/IR line emission. However optical/IR spectroscopy reveals the formation of a new inner disc with significant density and emission strength at small radii; the disc has proven to be stable over 5 months in this intermediate state.
Multiwavelength observations of the Be/X-ray binary 4U1145-619
1997
We report optical and infrared observations of the massive X-ray binary system 4U1145-619 (V801 Cen) which show that the circumstellar disc of the Be star component is in decline. Infrared J,H,K,L magnitudes of V801Cen have been monitored from 1993 March to 1996 April. H alpha spectra have been obtained throughout the same period. We find that both the infrared excess and the Balmer emission have been in decline throughout the period of observations. A 13 year optical and X-ray history of the source has been collated, revealing a possible correlation between the optical and X-ray activity. In addition, we have used u,v,b,y,beta indices, corrected for both circumstellar and interstellar effe…
Four colour photometry of binary systems
1998
This paper presents new uvby light curves of the detached eclipsing binary CR Cas together with some H measurements. From the analysis of the photometry we have estimated preliminary values for interstellar red- dening and distance, radiative parameters of both compo- nents and an approximation to the geometrical elements of the system. The intrinsic photometric indices are com- patible with spectral types B0.5V + B1V.
Scaling and mean-field-like behaviour in phase separation processes
1985
Extensive Monte Carlo calculations are used to study the still not well understood process of phase separation in binary systems. The results show that for a separation dominated by long-wavelength fluctuations a mean-field description holds in certain concentration regions. This, however, is only true for short times after the system has been brought into a non-equilibrium state. A crucial parameter is the interaction range. It determines the region and the time where the mean field description is valid. At later times the structure factor exhibits dynamical scaling. Scaling is also investigated for the metastable states. The results are applicable to polymer blends with long chains or bin…
X-ray spectroscopy of the high-mass X-ray binary 4U 1700-37
2004
We present the first results of a monitoring campaign of the high-mass X-ray binary system 4U 1700-37/HD 153919, carried out with XMM-Newton.We have observed the high-mass X-ray binary (HMXB) 4U 1700-37 with XMM-Newton at four orbital phases in February 2001. 4U 1700-37 is powered by the dense stellar wind of the O supergiant HD 153919. Numerous X-ray flares are observed with a typical duration, of the order of half an hour. We focus on three intervals in which the data are not affected by pile up: the eclipse, the eclipse egress and a low-flux part around orbital phase ϕ ~ 0.28.