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1.
We determined the spectroscopic-interferometric orbit of the binary red dwarf Gliese 150.2 with a period of 13.84 yr and a semimajor axis of 0.257 arcsec. Based on the orbital elements and on accurate measurements of the magnitude difference at several wavelengths, we estimated the spectral types and masses of the components (K0 V and M0 V, 0.79 and 0.55M ⊙) and the dynamical parallax of the binary (40.4 mas).  相似文献   

2.
We have computed a combined spectroscopic-interferometric orbit for the nearby binary Gliese 600 discovered by us. The orbital period is 2.78 years, and the semimajor axis is 100 mas (0.1″). Its M0 V components are almost identical and have a mass of 0.5M ⊙. The mass ratio is uncertain because of the low radialvelocity semiamplitude (7 km s?1) associated with the low orbital inclination (37°). The orbital parallax of the binary (52±11 mas) matches its dynamical and photometric parallaxes but differs significantly from the Hipparcos parallax (44.3±1.6) mas; the latter was probably distorted by the orbital motion that was not taken into account.  相似文献   

3.
An inequality that allows the minimum sum of the component masses for a binary, M0, to be determined was derived from simple geometric considerations. This quantity satisfies the observed orbital motion according to Newton's law with a known parallax. The M0 value can be calculated if the apparent-motion parameters for the components, including the curvature of the observed short orbital arc, were determined from observations. We estimated M0 for 14 Pulkovo program stars for which the apparent orbital arc covered with observations was no less than 10°. We compare M0 with the masses estimated from the mass-luminosity relation. A significant mass excess was found for the star ADS 10329.  相似文献   

4.
We report the physical and orbital parameters of the visible component of the spectroscopic binary HD37737 (m V = 8.03). The observations were performed with the 1.2-m telescope of the Kourovka Astronomical Observatory of the Ural Federal University in 2012 and the 6-m BTA telescope of the SAO RAS in 2007 and 2009. Radial velocities were measured separately from each spectral line of the list by the cross-correlation method with a synthetic spectrum. The latter was calculated using the grids of non-LTE model atmospheres with solar chemical compositions. A significant difference in the epochs of observations (2005–2012) allowed to refine the orbital period of the star (7 · d 84705) and the orbital elements of the binary system. We obtained an estimate of the mass function f(m) = 0.23 ± 0.02M ⊙. The best agreement between the synthetic and observed spectra is achieved at T eff = 30 000 K and log g = 3.50 according to the observations on both instruments. The obtained parameters correspond to a star of spectral type O9.5 III, with mass estimated at 26 ± 2M ⊙. The minimum mass estimate of the secondary component of the binary is 6.2 ± 0.5M ⊙. We have discovered a fact that the velocities, obtained from different spectral lines, differ, which is typical for giant stars. Engaging additional spectra, obtained in 2005 with the 2.1-m KPNO telescope, we investigated the effect of this fact on the estimate of the speed of the system’s center of mass. The difference in the velocities of various lines is approximately the same in the spectra, obtained at all the three instruments. The obtained ratios suggest that the deeper layers of the atmosphere of the star are moving with a greater velocity than the outer layers. Depending on the line, the estimate of the heliocentric velocity of the binary’s center of mass varies in the range from ?11 to 1 km/s.  相似文献   

5.
We present a detailed determination of the astrophysical parameters of the chromospherically active binary star EI Eridani. Our new radial velocities allow to improve the set of orbital elements and reveal long‐term variations of the barycentric velocity. A possible third‐body orbit with a period of ≈19 years is presented. Absolute parameters are determined in combination with the Hipparcos parallax. EI Eri's inclination angle of the rotational axis is confined to 56°.0 ± 4°.5, ist luminosity class IV is confirmed by its radius of 2.37 ± 0.12 R⊙. A comparison to theoretical stellar evolutionary tracks suggests a mass of 1.09 ± 0.05 M⊙ and an age of ≈ 6.15 Gyr. The present investigation is the basis of our long‐term Doppler imaging study of its stellar surface (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

6.
A series of highly accurate photoelectric observations of the eclipsing binary MZ Lac was obtained with a 48-cm AZT-14 reflector at the Tien-Shan High-Altitude Station of the Sternberg Astronomical Institute from 1985 to 2004 to study its apsidal motion. We constructed a consistent system of physical and geometrical parameters of the components and the binary’s orbit: we determined their masses (M1 = 1.50M⊙, M2 = 1.29M⊙), radii (R1 = 1.86R⊙, R2 = 1.35R⊙), luminosities (L1 = 0.79L⊙, L2 = 0.45L⊙), surface gravities (logg1 = 4.06, logg2 = 4.27), age (t = 1.9 × 109 yr), and the distance to the binary (d = 510 pc). The binary exhibits apsidal motion with the period Uobs = 480 ± 40 yr, while its theoretically expected value is Uth = 450 ± 40 yr. Spectroscopic studies of MZ Lac and calculations of the absolute parameters of the components are required to test our conclusions.  相似文献   

7.
We present a new orbit for the visual binary ADS 8630 = γ Vir. Although it is one of the first visual double stars discovered, its orbital elements were still poorly known. Indeed the very high eccentricity of the orbit and the difficulty of observing the pair at periastron passage in 1836 has meant that it is only now that sufficient measures of the recent close approach in 2005 have allowed an orbital analysis which predicts the angular motion to an acceptable degree of accuracy. We present a series of 35 speckle measurements of ADS 8630 obtained with PISCO in Merate between 2004 and 2006. Those measures have been crucial for determining the new orbital elements since they cover an arc of 130 degrees in the apparent orbit and include the periastron passage of 2005. The masses of the individual F0V components of the binary are found to be 1.40 M⊙ with an accuracy of about 3%. We also investigate in detail the possibility of the presence of a third body in the system, that was proposed by other authors. The high‐angular resolution infra‐red image of γ Vir that we obtained in June 2006 with the LuckyCam instrument on the ESO NTT shows the absence of any companion as faint as a M0V star at a distance larger than 0.4″. Combined with the analysis of the residuals of our orbit, the values found for the masses of the individual components and the radial velocity measurements, this observation rules out the presence in the system of a third companion with a mass larger than 0.3 M⊙. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

8.
《New Astronomy》2007,12(2):95-103
Low metallicity very massive stars with an initial mass between 140M⊙ and 260M⊙ can be subdivided into two groups: those between 140M⊙ and 200M⊙ which produce a relatively small amount of Fe, and those with a mass between 200M⊙ and 260M⊙ where the Fe-yield ejected during the supernova explosion is enormous. We first demonstrate that the inclusion of the second group into a chemical evolutionary model for the Solar Neighbourhood predicts an early temporal evolution of Fe, which is at variance with observations whereas it cannot be excluded that the first group could have been present. We then show that a low metallicity binary with very massive components (with a mass corresponding to the first group) can be an efficient site of primary 14N production through the explosion of a binary component that has been polluted by the pair instability supernova ejecta of its companion. When we implement these massive binary 14N yields in a chemical evolution model, we conclude that very massive close binaries may be important sites of 14N enrichment during the early evolution of the Galaxy.  相似文献   

9.
The system of subdwarfs G89-14 is one of the most metal-poor multiple stars with an atmospheric metal abundance [m/H] = ?1.9. Speckle interferometry at the 6-m BTA telescope has revealed that G89-14 consists of four components. Measurements of the magnitude difference between the components and published data have allowed their masses to be estimated: M A ≈ 0.67 M ⊙, M B ≈ 0.24M ⊙,M C ≈ 0.33M ⊙, andM D ≈ 0.22M ⊙. The ratio of the orbital periods of the subsystems has been obtained, 0.52 yr: 3000 yr: 650 000 yr (1: 5769: 1 250 000), indicative of a high degree of hierarchy o fG89-14 and its internal dynamical stability. The calculated Galactic orbital elements and the low metallicity of the quadruple system suggest that it belongs to the Galactic halo.  相似文献   

10.
Based on a new set of electronic spectra in a relatively wide spectral range (3500–8300 Å) and using the methods of spectrum disentangling (code KOREL) and solution of RV curves (code FOTEL), we determined new orbital elements of the binary star κ Dra. The solution of the radial velocity curves for Balmer and some other strong metallic lines suggested a circular orbit and led to the following orbital elements: period P = 61.555 ± 0.029 days, epoch of periastron passage T periast = 49980.22 ± 0.59, RV semi-amplitude K 1 = 6.81 ± 0.24 km s?1, and a mass function of f(m) = 0.002 M ⊙. Lines of the secondary were not detected. In addition, moving absorption bumps in the violet peaks of Hα and Hβ lines were found to be phase-locked with the orbital period. Their presence suggests some kind of interaction between the binary components.  相似文献   

11.
We present the results of our spectroscopic observations of the eclipsing binary SZ Cam performed with the 1-m (Zeiss-1000) and 6-m (BTA) telescopes at the Special Astrophysical Observatory of the Russian Academy of Sciences in 2000 and 2003. Based on our results and published data, we have calculated new values for the component mass ratio, q = 0.72 ± 0.02, the radial velocity of SZ Cam relative to the Solar system barycenter, V 0 =?10.6 ± 2.0 km s?1, and the semi-amplitudes of the radial velocity curves for both components, K 1 = 192.0 ± 2.6 and K 2 = 266.4 ± 2.5 km s?1. The orbital semimajor axes and masses of the components have been determined: α1 = 10.4R ⊙, α2 = 14.5R ⊙, M 1 = 16.7M ⊙, M 2 = 12.0M ⊙. New light elements and parameters of the radial velocity curve for the third body have been obtained. The mass of the secondary component of the third body M 2 3b is discussed. Its lower limit is estimated to be M 2 3b = 1.4M ⊙.  相似文献   

12.
In this paper, we report a rare reflection effect eclipsing sdB+dM binary, 2M?1533+3759. It is the seventh eclipsing sdB+dM binary that has been discovered to date. This system has an orbital period of 0.16177042 day and a velocity semi-amplitude of 71.1 km?s?1. Using a grid of zero-metallicity NLTE model atmospheres, we derived T eff=29250 K, log?g=5.58 and [He/H]=?2.37 from spectra taken near the reflection effection minimum. Lightcurve modeling resulted in a system mass ratio of 0.301 and an orbital inclination angle of 86.6°. The derived primary mass for 2M?1533+3759, 0.376±0.055 M ⊙, is significantly lower than the canonical mass (0.48 M ⊙) found for most previously investigated sdB stars. This implies an initial progenitor mass >1.8 M ⊙, at least a main sequence A star and perhaps even one massive enough to undergo non-degenerate helium ignition.  相似文献   

13.
The visual binary star ADS 15571 has been observed with the 26″ refractor at Pulkovo since 1960. Periodic perturbations in the relative motion of the components are studied in this paper. The visible motion of the component B was resolved into orbital motion of the barycenter relative to component A and an elliptical motion of the photocenter relative to the barycenter. The visible ellipse of the photocenter motion is used to determine the elements of the orbit by the direct geometric method of A. A. Kiselev and estimate the perturbing mass. The minimum mass of the invisible companion is 0.62 M⊙. __________ Translated from Astrofizika, Vol. 49, No. 3, pp. 467–474 (August 2006).  相似文献   

14.
A combined spectroscopic-interferometric orbit is computed for the primary component of the visual binary star HR 7272=ADS 12101. The orbital period is 3.55 years; semimajor axis 0.″074. Radial velocities of both components were determined by correlation techniques; their semi-amplitudes are 6.6 and 8.4 km s?1. Because those amplitudes are so modest, the correlation dips are never well resolved, and the mass ratio and orbital parallax remain poorly determined. Adopting normal masses for the components, we obtain the dynamical parallax; the Hipparcos parallax for this star seems to have a large error, probably because the orbital motion was not taken into account. The visual component B belongs to this system and has a constant radial velocity.  相似文献   

15.
This paper reports the results of spectroscopic observations of UUCas obtained with the highresolution (R = 15 000) fiber-fed echelle spectrometer of the 1.2-m telescope of Kourovka Astronomical Observatory of Ural Federal University. The radial velocities of the secondary, more massive and fainter component are measured for the first time. The component mass ratio is found to be q = M 1/M 2 = 0.54. The component masses, M 1 = 9.5M ⊙ and M 2 = 17.7M ⊙, and the radius of the or bit, A = 52.7R ⊙, are computed for the published orbital inclination of i ~ 69°. Evidence is presented for a disk surrounding the more massive component and a common expanding envelope.  相似文献   

16.
New BV light curves and times of minimum light for the short period W UMa system LO And were analyzed to derive the preliminary physical parameters of the system. The light curves were obtained at Ankara University Observatory during 5 nights in 2003. A new ephemeris is determined for the times of primary minimum. The analysis of the light curves is made using the Wilson‐Devinney 2003 code. The present solution reveals that LO And has a photometric mass ratio q = 0.371 and is an A‐type contact binary. The period of the system is still increasing, which can be attributed to light‐time effect and mass transfer between the components. With the assumption of coplanar orbit of the third body the revealed mass is M3 = 0.21M⊙. If the period change dP/dt = 0.0212 sec/yr is caused only by the mass transfer between components (from the lighter component to the heavier) the calculated mass transfer rate is dm/dt = 1.682×10−7M⊙/yr. The absolute radii and masses estimated for the components, based on our photometric solution and the absolute parameters of the systems which have nearly same period are R1 = 1.30R⊙, R2 = 0.85R⊙, M1 = 1.31M⊙, M2 = 0.49M⊙ respectively for the primary and secondary components. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

17.
The paper presents the results of spectroscopic research of the high-mass X-ray binary IGRJ17544-2619 optical component that were carried out with the RTT-150. The analysis of a long series of spectroscopic observations of the optical star of IGRJ17544-2619 system in 2007–2011 was carried out. Orbital parameters of the system were obtained: γ-velocity of 47 km/s, semiamplitude of radial velocity curve K = 30.5 km/s, eccentricity e = 0.44, longitude of the periastron ω = 142°, and an orbital period of the system of 12.17 days. The lower limit of the compact object mass was found to be equal to M = 2.82M ⊙.  相似文献   

18.
We present new photometric observations covering eight minima times for the eclipsing binary GSC 1042-2191. The light curves in BVRI colors were analyzed by using WD-code for the system parameters. Eight minima times were obtained from the new observations. The system is found a low mass ratio (q = 0.148), A-type over-contact binary with a fill out parameter of f = 65.01 ± 12.18%. The preliminary absolute dimensions (M1= 1.26 ± 0.06 M⊙, M2 = 0.18 ± 0.06 M⊙, R1 = 1.54 ± 0.20 R⊙, R2 = 0.69 ± 0.01 R⊙, L1 =3.30 ± 0.30 L⊙ and L2 = 0.59 ± 0.20 L⊙) indicate the very much oversized and over-luminous secondary component, by assuming the present luminosity of the secondary is its main sequence luminosity, we predict the original mass is about 0.8 M⊙, this means the present secondary could be transferred and/or lost 77% of its original mass and only its core is left.  相似文献   

19.
A period study of the young binary AR Aur based on the extensive series of published photoelectric/ccd minima times indicates the cyclic (O – C) variation for the system. This continuous oscillatory variation covers almost three cycles, about 6000 orbital periods, by the present observational data. It can be attributed to the light‐time effect due to a third body with a period of 23.68 ± 0.17 years in the system. The analysis yields a light‐time semi‐amplitude of 0.0084 ± 0.0002 day and an orbital eccentricity of 0.20 ± 0.04. Adopting the total mass of AR Aur, the mass of the third body assumed in the co‐planar orbit with the binary is M3 = 0.54 ± 0.03 M⊙ and the semimajor axis of its orbit is a3 = 13.0 + 0.2 AU. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

20.
A model for the formation and evolution of binary millisecond radio pulsars in systems with low mass companions (<0.1 M⊙) is investigated using a binary population synthesis technique. Taking into account the non conservative evolution of the system due to mass loss from an accretion disk as a result of propeller action and from the companion via ablation by the pulsar, the transition from the accretion powered to rotation powered phase is investigated. It is shown that the operation of the propeller and ablation mechanisms can be responsible for the formation and evolution of black widow millisecond pulsar systems from the low mass X-ray binary phase at an orbital period of ～0.1 day. For a range of population synthesis input parameters, the results reveal that a population of black widow millisecond pulsars characterized by orbital periods as long as ～0.4 days and companion masses as low as ～0.005 M⊙ can be produced. The orbital periods and minimum companion mass of this radio millisecond pulsar population critically depend on the thermal bloating of the semi-degenerate hydrogen mass losing component, with longer orbital periods for a greater degree of bloating. Provided that the radius of the companion is increased by about a factor of 2 relative to a fully degenerate, zero temperature configuration, an approximate agreement between observed long orbital periods and theoretical modeling of hydrogen rich donors can be achieved. We find no discrepancy between the estimated birth rates for LMXBs and black widow systems, which on average are ${\sim}1.3\times10^{-5}~{\rm yr}^{-1}$ and $1.3\times10^{-7}~{\rm yr}^{-1}$ respectively.  相似文献   

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