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1.
In our evolutionary population synthesis models, samples of binaries are reproduced by a ' patched ' Monte Carlo simulation and the stellar masses, integrated   J ,  H ,  K ,  L ,  L 2  and M magnitudes, mass-to-light ratios and broad colours involving infrared bands are presented for an extensive set of instantaneous-burst binary stellar populations. In addition, the fluctuations in the integrated colours, which have been given by Zhang et al., are reduced.
By comparing the results for binary stellar populations with (Model A) and without (Model B) binary interactions, we show that the inclusion of binary interactions makes the stellar mass of a binary stellar population smaller (  ∼3.6–4.5  per cent during the past 15 Gyr), magnitudes greater (except   U , ∼ 0.18 mag  at the most), colours bluer (∼0.15 mag for   V − K   at the most) and mass-to-light ratios greater (∼0.06 for K band) except those in the U and B passbands at higher metallicities. Binary interactions make the V magnitude less sensitive to age, and R and I magnitudes more sensitive to metallicity.
Given an age, the absolute values of the differences in the stellar mass, magnitudes and mass-to-light ratios (except those in the U and B bands) between Models A and B reach a maximum at   Z = 0.0001  , i.e. the effects of binary interactions on these parameters reach a maximum, while the differences in some colours reach a maximum at   Z ∼ 0.01–0.0004  . In contrast, the absolute value of the difference in the stellar mass is minimal at   Z = 0.03  ; those in the   U ,  B ,  V   magnitudes and the mass-to-light ratios in the U and B bands reach a minimum at   Z ∼ 0.01–0.004  .  相似文献   

2.
We consider the magnetic and spin evolution of the X-ray binary pulsars Her X-1 and 4U 1626–67, assuming that their magnetic fields are of crustal origin. We adopt the standard evolutionary model which implies that the neutron star passes through several phases in a binary system ('isolated pulsar' – propeller – wind accretion – Roche lobe overflow). In the framework of the model under consideration, the strong magnetic fields of relatively old pulsars like Her X-1 and 4U 1626–67 can naturally be understood if, at their birth, they had a sufficiently strong magnetic field, ∼3 × 1013 G, comparable to the maximal field observed in radio pulsars.  相似文献   

3.
We propose an explanation for the puzzling appearance of a wide blue absorption wing in the He  i  λ10830 Å  P Cygni profile of the massive binary star η Car several months before periastron passage. Our basic assumption is that the colliding winds region is responsible for the blue wing absorption. By fitting observations, we find that the maximum outflow velocity of this absorbing material is  ∼2300 km s−1  . We also assume that the secondary star is towards the observer at periastron passage. With a toy model, we achieve two significant results. (1) We show that the semimajor axis orientation we use can account for the appearance and evolution of the wide blue wing under our basic assumption. (2) We predict that the Doppler shift (the edge of the absorption profile) will reach a maximum 0–3 weeks before periastron passage, and not necessarily exactly at periastron passage or after periastron passage.  相似文献   

4.
Chevalier & Ilovaisky use Hipparcos data to show that the X-ray binary systems LSI+61° 303 and A0535+262 are a factor of 10 closer (i.e. d  ∼ few hundred pc) than previously thought ( d  ∼ kpc). We present high-quality CCD spectra of the systems, and conclude that the spectral types, reddening and absolute magnitudes of these objects are strongly inconsistent with the closer distances. We propose that the Hipparcos distances to these two systems are incorrect owing to their relatively faint optical magnitudes.  相似文献   

5.
We present  0.9–2.5 μm  spectroscopy with   R ∼800  and  1.12–1.22 μm  spectroscopy with   R ∼5800  for the M dwarfs Gl 229A and LHS 102A, and for the L dwarf LHS 102B. We also report IZJHKL ' photometry for both components of the LHS 102 system, and L ' photometry for Gl 229A. The data are combined with previously published spectroscopy and photometry to produce flux distributions for each component of the kinematically old disc M/L dwarf binary system LHS 102 and the kinematically young disc M/T dwarf binary system Gliese 229. The data are analysed using synthetic spectra generated by the latest 'AMES-dusty' and 'AMES-cond' models by Allard & Hauschildt. Although the models are not able to reproduce the overall slope of the infrared flux distribution of the L dwarf, most likely because of the treatment of dust in the photosphere, the data for the M dwarfs and the T dwarf are well matched. We find that the Gl 229 system is metal-poor despite having kinematics of the young disc, and that the LHS 102 system has solar metallicity. The observed luminosities and derived temperatures and gravities are consistent with evolutionary model predictions if the Gl 229 system is very young  (age∼30 Myr)  with masses (A,B) of (0.38,≳0.007) M⊙, and the LHS 102 system is older, aged  1–10 Gyr  with masses (A,B) of (0.19,0.07) M⊙.  相似文献   

6.
We have analysed the kinematical parameters of Cir X-1 to constrain the nature of its companion star, the eccentricity of the binary and the pre-supernova parameter space. We argue that the companion is most likely to be a low-mass (≲2.0 M⊙) unevolved star and that the eccentricity of the orbit is 0.94±0.04. We have evaluated the dynamical effects of the supernova explosion and we find it must have been asymmetric. On average , we find that a kick of ∼740 km s−1 is needed to account for the recently measured radial velocity of +430 km s−1 (Johnston, Fender & Wu) for this extreme system. The corresponding minimum kick velocity is ∼500 km s−1. This is the largest kick needed to explain the motion of any observed binary system. If Cir X-1 is associated with the supernova remnant G321.9-0.3 then we find a limiting minimum age of this remnant of ∼60 000 yr. Furthermore, we predict that the companion star has lost ∼10 per cent of its mass as a result of stripping and ablation from the impact of the supernova shell shortly after the explosion.  相似文献   

7.
During the past decade, several observational and theoretical works have provided evidence of the binary nature of η Carinae. Nevertheless, there is still no direct determination of the orbital parameters, and the different current models give contradictory results. The orbit is, in general, assumed to coincide with the Homunculus equator although the observations are not conclusive. Among all systems, η Car has the advantage that it is possible to observe both the direct emission of line transitions in the central source and its reflection by the Homunculus, which is dependent on the orbital inclination. In this work, we studied the orbital phase-dependent hydrogen Paschen spectra reflected by the south-east lobe of the Homunculus to constrain the orbital parameters of η Car and determine its inclination with respect to the Homunculus axis. Assuming that the emission excess originates in the wind–wind shock region, we were able to model the latitude dependence of the spectral line profiles. For the first time, we were able to estimate the orbital inclination of η Car with respect to the observer and to the Homunculus axis. The best fit occurs for an orbital inclination to the line of sight of   i ∼ 60°± 10°  , and   i *∼ 35°± 10°  with respect to the Homunculus axis, indicating that the angular momenta of the central object and the orbit are not aligned. We were also able to fix the phase angle of conjunction as  ∼−40°  , showing that periastron passage occurs shortly after conjunction.  相似文献   

8.
Using new and archival radio data, we have measured the proper motion of the black hole X-ray binary V404 Cyg to be  9.2 ± 0.3 mas yr−1  . Combined with the systemic radial velocity from the literature, we derive the full three-dimensional heliocentric space velocity of the system, which we use to calculate a peculiar velocity in the range 47–102 km s−1, with a best-fitting value of 64 km s−1. We consider possible explanations for the observed peculiar velocity and find that the black hole cannot have formed via direct collapse. A natal supernova is required, in which either significant mass  (∼11 M⊙)  was lost, giving rise to a symmetric Blaauw kick of up to ∼65 km s−1, or, more probably, asymmetries in the supernova led to an additional kick out of the orbital plane of the binary system. In the case of a purely symmetric kick, the black hole must have been formed with a mass  ∼9 M⊙  , since when it has accreted  0.5–1.5 M⊙  from its companion.  相似文献   

9.
Recent spectropolarimetric observations of Ap and Bp stars with improved sensitivity have suggested that most Ap and Bp stars are magnetic with dipolar fields of at least a few hundred gauss. These new estimates suggest that the range of magnetic fluxes found for the majority of magnetic white dwarfs is similar to that of main-sequence Ap–Bp stars, thus strengthening the empirical evidence for an evolutionary link between magnetism on the main sequence and magnetism in white dwarfs. We draw parallels between the magnetic white dwarfs and the magnetic neutron stars and argue that the observed range of magnetic fields in isolated neutron stars  ( Bp ∼ 1011–1015 G)  could also be explained if their mainly O-type progenitors have effective dipolar fields in the range of a few gauss to a few kilogauss, assuming approximate magnetic flux conservation with the upper limit being consistent with the recent measurement of a field of   Bp ∼ 1100 G  for θ Orion C.
In the magnetic field–rotation diagram, the magnetic white dwarfs can be divided into three groups of different origin: a significant group of strongly magnetized slow rotators  ( P rot∼ 50 –100 yr)  that have originated from single-star evolution, a group of strongly magnetized fast rotators  ( P rot∼ 700 s)  , typified by EUVE J0317–853, that have originated from a merger, and a group of modest rotators ( P rot∼ hours–days) of mixed origin (single-star and CV-type binary evolution). We propose that the neutron stars may similarly divide into distinct classes at birth , and suggest that the magnetars may be the counterparts of the slowly rotating high-field magnetic white dwarfs.  相似文献   

10.
We applied the aton evolutionary code to the computation of detailed grids of standard (non-rotating) and rotating pre-main sequence (PMS) models and computed their adiabatic oscillation spectra, with the aim of exploring the seismic properties of young stars. As, until now, only a few frequencies have been determined for ∼40 PMS stars, the way of approaching the interpretation of the oscillations is not unique. We adopt a method similar to the matching mode method by Guenther and Brown making use, when necessary, also of our rotating evolutionary code to compute the models for PMS stars. The method is described by a preliminary application to the frequency spectrum of two PMS stars (85 and 278) in the young open cluster NGC 6530. For the Star 85, we confirm with self-consistent rotating models, previous interpretation of the data, attributing three close frequencies to the mode   n = 4, l = 1  and   m = 0  , +1 and −1. For the Star 278, we find a different fit for the frequencies, corresponding to a model within the original error box of the star, and dispute the possibility that this star has a T eff much cooler that the red boundary of the radial instability strip.  相似文献   

11.
We report spectral time series of the late O-type runaway supergiant HD 188209. Radial velocity variations of photospheric absorption lines with a possible quasi-period of ∼6.4 d have been detected in high-resolution echelle spectra. Night-to-night variations in the position and strength of the central emission reversal of the H α profile occurring over ill-defined time-scales have been observed. The fundamental parameters of the star are derived using state-of-the-art plane-parallel and unified non-LTE model atmospheres, the latter including the mass-loss rate. The derived helium abundance is moderately enhanced with respect to solar, and the stellar masses are lower than those predicted by the evolutionary models. The binary nature of this star is not suggested either from Hipparcos photometry or from radial velocity curves.  相似文献   

12.
Theoretical X-ray line profiles from colliding wind binaries   总被引：1，自引：0，他引：1  
We present theoretical X-ray line profiles from a range of model colliding wind systems. In particular, we investigate the effects of varying the stellar mass-loss rates, the wind speeds and the viewing orientation. We find that a wide range of theoretical line profile shapes is possible, varying with orbital inclination and phase. At or near conjunction, the lines have approximately Gaussian profiles, with small widths  (HWHM ∼ 0.1 v ∞)  and definite blueshifts or redshifts (depending on whether the star with the weaker wind is in front or behind). When the system is viewed at quadrature, the lines are generally much broader  (HWHM ∼ v ∞)  , flat-topped and unshifted. Local absorption can have a major effect on the observed profiles – in systems with mass-loss rates of a few times  10−6 M⊙ yr−1  the lower energy lines  ( E  ≲ 1 keV)  are particularly affected. This generally results in blueward-skewed profiles, especially when the system is viewed through the dense wind of the primary. The orbital variation of the linewidths and shifts is reduced in a low-inclination binary. The extreme case is a binary with   i = 0°  , for which we would expect no line profile variation.  相似文献   

13.
Lorimer et al. have recently reported that the spin-down age (∼7 × 109 yr) of the low-mass binary pulsar PSR J1012+5307 is much higher than the cooling age (3 × 108 yr) of its white dwarf companion. The proposed solutions for this discrepancy are outlined and discussed. In particular, the revised cooling age estimate proposed by Alberts et al. agrees with data from other low-mass binary pulsar systems if a transition to the 'classical' cooling regime occurs between ∼0.14 and ∼0.28 M⊙. If this transition is excluded, PSR J1012+5307 seems to have finished its accretion phase far from the spin-up line.  相似文献   

14.
We present high-time-resolution optical photometry of the eclipsing binary UZ For using a superconducting tunnel junction (STJ) device, a photon-counting array detector with intrinsic energy resolution. Three eclipses of the ∼18-mag 126.5-min orbital binary were observed using a 6×6 array of tantalum STJs at the 4.2-m William Herschel Telescope on La Palma. The detector presently provides individual photon arrival-time accuracy to about 5 μs, and a wavelength resolution of about 60 nm at 500 nm, with each array element capable of counting up to ∼5000 photon s−1. The data allow us to place accurate constraints on the accretion geometry from our time- and spectrally resolved monitoring, especially of the eclipse ingress and egress. We find that there are two small accretion regions, located close to the poles of the white dwarf. The positions of these are accurately constrained, and show little movement from eclipse to eclipse, even over a number of years. The colour of the emission from the two regions appears similar, although their X-ray properties are known to be significantly different: we argue that the usual accretion shock may be absent at the non-X-ray-emitting region, and instead the flow here interacts directly with the white dwarf surface; alternatively, a special grazing occultation of this region is required. There is no evidence for any quasi-periodic oscillations on time-scales of the order of seconds, consistent with relatively stable cyclotron cooling in each accretion region.  相似文献   

15.
We have monitored the atoll-type neutron star low-mass X-ray binary 4U 1636−53 with the Rossi X-ray Timing Explorer ( RXTE ) for more than 1.5 yr. Our campaign consisted of short (∼2 ks) pointings separated by 2 d, regularly monitoring the spectral and timing properties of the source. During the campaign we observed a clear long-term oscillation with a period of ∼30–40 d, already seen in the light curves from the RXTE All-Sky Monitor, which corresponded to regular transitions between the hard (island) and soft (banana) states. We detected kilohertz (kHz) quasi-periodic oscillations (QPOs) in about a third of the observations, most of which were in the soft (banana) state. The distribution of the frequencies of the peak identified as the lower kHz QPO is found to be different from that previously observed in an independent data set. This suggests that the kHz QPOs in the system shows no intrinsically preferred frequency.  相似文献   

16.
The parameter space favourable for the resonant excitation of free oscillation modes by dynamic tides in close binary components is explored using qualitative considerations to estimate the order of magnitude of the tidal force and the frequency range covered by the tidally induced oscillations. The investigation is valid for slowly rotating stars with masses in the interval between 2 and  20 M⊙  , and an evolutionary stage ranging from the beginning to the end of the main sequence. Oscillation modes with eigenfrequencies of the order of five times the inverse of the dynamical time-scale  τdyn  of the star, i.e. the lowest-order p -modes, the f -mode and the lowest-order g +-modes, are found to be outside the favourable parameter space since their resonant excitation requires orbital eccentricities that are too high for the binary to stay detached when the components pass through the periastron of their relative orbit. Resonances between dynamic tides and g +-modes with frequencies of the order of half of the inverse of the dynamical time-scale of the star on the other hand are found to be favourable for orbital periods up to  ∼200τdyn  , provided that the binary mass ratio q is larger than 1/3, and the orbital eccentricity e is larger than ∼0.25. This favourable range comes down to orbital periods of up to 5–12 d in the case of  2–20 M⊙  zero-age main-sequence binary components, and orbital periods of up to 21–70 d in the case of terminal main-sequence binary components.  相似文献   

17.
We present a detailed kinematical analysis of the young compact hourglass-shaped planetary nebula Hb 12. We performed optical imaging and long-slit spectroscopy of Hb 12 using the Manchester echelle spectrometer with the 2.1-m San Pedro Mártir telescope. We reveal, for the first time, the presence of end caps (or knots) aligned with the bipolar lobes of the planetary nebula shell in a deep [N  ii ]λ6584 image of Hb 12. We measured from our spectroscopy radial velocities of  ∼120 km s−1  for these knots.
We have derived the inclination angle of the hourglass-shaped nebular shell to be ∼65° to the line of sight. It has been suggested that Hb 12's central star system is an eclipsing binary which would imply a binary inclination of at least 80°. However, if the central binary has been the major shaping influence on the nebula, then both nebula and binary would be expected to share a common inclination angle.
Finally, we report the discovery of high-velocity knots with Hubble-type velocities, close to the core of Hb 12, observed in Hα and oriented in the same direction as the end caps. Very different velocities and kinematical ages were calculated for the outer and inner knots showing that they may originate from different outburst events.  相似文献   

18.
The accretion-induced neutron star (NS) magnetic field evolution is studied through considering the accretion flow to drag the field lines aside and dilute the polar-field strength, and as a result the equatorial field strength increases, which is buried inside the crust on account of the accretion-induced global compression of star crust. The main conclusions of model are as follows: (i) the polar field decays with increase in the accreted mass; (ii) the bottom magnetic field strength of about 108 G can occur when the NS magnetosphere radius approaches the star radius, and it depends on the accretion rate as     ; and (iii) the NS magnetosphere radius decreases with accretion until it reaches the star radius, and its evolution is little influenced by the initial field and the accretion rate after accreting  ∼0.01 M⊙  , which implies that the magnetosphere radii of NSs in low-mass X-ray binaries would be homogeneous if they accreted the comparable masses. As an extension, the physical effects of the possible strong magnetic zone in the X-ray NSs and recycled pulsars are discussed. Moreover, the strong magnetic fields in the binary pulsars PSR 1831−00 and PSR 1718−19 after accreting about  0.5 M⊙  in the binary-accretion phase,  8.7 × 1010  and  1.28 × 1012 G  , respectively, can be explained through considering the incomplete frozen flow in the polar zone. As an expectation of the model, the existence of the low magnetic field  (∼3 × 107 G)  NSs or millisecond pulsars is suggested.  相似文献   

19.
The role of binary progenitors of neutron stars (NSs) in the apparent distribution of space velocities and spin–velocity alignment observed in young pulsars is studied. We performed a Monte Carlo synthesis of pulsar populations originated from single and binary stars with different assumptions about the NS natal kick (kick–spin alignment, kick amplitude and kick reduction in electron-capture supernovae in binary progenitors with initial main-sequence masses from the range  8–11 M⊙  which experienced mass exchange due to Roche lobe overflow). The calculated spin–velocity alignment in pulsars is compared with data inferred from radio polarization measurements. The observed space velocity of pulsars is found to be mostly affected by the natal kick velocity form and its amplitude; the fraction of binaries is not important here for reasonably large kicks. The natal kick–spin alignment is found to strongly affect the spin–velocity correlation of pulsars. Comparison with the observed pulsar spin–velocity angles favours a sizeable fraction of binary progenitors and kick–spin angles  ∼5°–20°  .  相似文献   

20.
We discuss the orbital elements of the multiple system Tr 16-104 which is usually believed to be a member of the open cluster Trumpler 16 in the Carina complex. We show that Tr 16-104 could be a hierarchical triple system consisting of a short-period (2.15 d) eclipsing O7 V+O9.5 V binary bound to a B0.2 IV star. Our preliminary orbital solution of the third body indicates that the B star most probably describes an eccentric orbit with a period of ∼285 or ∼1341 d around the close binary. Folding photometric data from the literature with our new ephemerides, we find that the light curve of the close binary exhibits rather narrow eclipses indicating that the two O stars must be well inside their Roche lobes. Our analysis of the photometric data yields a lower limit on the inclination of the orbit of the close binary of i ≥77° . The stellar radii and luminosities of the O7 V and O9.5 V stars are significantly smaller than expected for stars of this spectral type. Our results suggest that Tr 16-104 lies at a distance of the order of 2.5 kpc and support a fainter absolute magnitude for zero-age main-sequence O stars than usually adopted. We find that the dynamical configuration of Tr 16-104 corresponds to a hierarchical system that should remain stable provided that it suffers no strong perturbation. Finally, we also report long-term temporal variations of high-velocity interstellar Ca  ii absorptions in the line of sight towards Tr 16-104.  相似文献   

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