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1.
The eclipsing binary NN Vir is a short period system showing an EW-type light curve. Photometric observations of NN Vir were done by Gomez–Ferrellad and Garcia–Melendo (1997) at Esteve Duran Observatory. The first spectroscopic observations of this system were obtained by Rucinski and Lu (1999). The radial velocity and light curves analysis was made with the latest version of the Wilson program (1998), and the geometric and physical elements of the system are derived. From the simultaneous solutions of the system, we determined the masses and radii of the components: 1.89 M ⊙ and 1.65 R ⊙ for the primary component; 0.93 M ⊙ and 1.23 R ⊙ for the secondary component. We estimated effective temperatures of 7030 K for the primary and 6977 K for the secondary component.  相似文献   

2.
Complete UBV light curves of the W Ursae Majoris binary V839 Ophobtained in the year 2000 are presented. The available spectroscopic data of V839 Oph is new and we used the first radial velocity data of this system obtained by Rucinski and Lu (1999)for analysis. The radial velocity and light curves analysis was made with the latest version of Wilson programme (1998) and the geometric and physical elements of the system are derived. By searching the simultaneous solutions of the system we have determined the masses and radii of the components: 1.61M ⊙and 1.49402R ⊙ for the primary component; 0.50M ⊙and 0.90147R ⊙ for the secondary component. We estimate deffective temperatures of 6650±18 (K) for the primary and6554±15 (K) for the secondary component. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

3.
UBV photometric observations and elements of TT Hydrae obtained by Kulkarni and Abhyankar (1980) are combined with the radial velocity curve of Popper (1979, personal communication) to derive the absolute dimensions and. a model of this important Algol system. While the photometric ratios of radii inV andB are in agreement givingk = 0.3812 for a limb darkening coefficient ofx = 0.6, application of Irwin’s (1947) method givesx = 0.4 forU. The primary is found to be a main sequence Al V star of mass 2.61M ⊙ and radius 2.01 R⊙, and the secondary is classified as a Kl III star of mass 0.70M ⊙ and radius 5.33R ⊙. The observed Fourier coefficients for the light outside the eclipse agree with those calculated from theory for the reflection and ellipticity effects. The system shows an ultraviolet excess of 0.5 to 0.6 magnitudes during primary eclipse, which is attributed to an asymmetric circumstellar distribution of matter around the primary. The evolutionary status of the secondary, which does not appear to fill its Roche lobe completely, is discussed.  相似文献   

4.
New ephemeris and the absolute parameters—masses, radii and luminosities—of the contact systems VW LMi and BX Dra have been obtained, by means of the analysis of the minima data available in the literature (for the determination of the ephemeris) and combining the previously published spectroscopic information and the results of the Wilson-Devinney method using photometric data (for the determination of the absolute parameters). The VW LMi O−C analysis confirms the multiplicity of the system detected previously from the spectroscopic data. Masses of the VW LMi contact system primary and secondary components are 1.67 ± 0.02M ⊙ and 0.70 ± 0.02M ⊙, respectively. The corresponding radii are 1.709 ± 0.007R ⊙ and 1.208 ± 0.006R ⊙, respectively. For the BX Dra contact system the masses are 2.19 ± 0.13M ⊙ and 0.63 ± 0.06M ⊙, and the radii, 2.13 ± 0.04R ⊙ and 1.26 ± 0.03R ⊙, for the primary and secondary, respectively. In both cases, the estimated luminosities seem to be slightly greater that the values derived from the Hipparcos distances.  相似文献   

5.
We present multi-colour CCD observations of the low-temperature contact binaries, V453 Mon and V523 Cas. Their light curves are modelled to determine a new set of stellar and orbital parameters. Analysis of mid-eclipse times yields a new linear ephemeris for both systems. A period decrease (dP/dt=2.3×10−7 days/yr) in V453 Mon is discovered. V523 Cas, however, is detected to show a period increase (dP/dt=9.8×10−8 days/yr) because of the mass transfer of a rate of 1.1×10−7 M⊙ yr−1, from a less massive donor. Using these findings we can determine the physical parameters of the components of V523 Cas to be M 1=0.76 (3)M ⊙, M 2=0.39 (2)M ⊙, R 1=0.74 (2)R ⊙, R 2=0.55 (2)R ⊙, L 1=0.19 (3)L ⊙, L 2=0.14 (3)L ⊙, and the distance of system as 46(9) pc.  相似文献   

6.
Based on two high-dispersion spectra of the close binary BW Boo, we have detected lines of the secondary component whose contribution to the combined spectrum does not exceed 2%. We have determined the rotation velocities of the components and spectroscopic orbital elements. Numerous lines of neutral and ionized iron have been used to determine the effective temperature and surface gravity for the primary component. The photometric light curves for this binary have been solved for the first time. Its primary component is an A2Vm star with a mass of 2 ± 0.1M ⊙ and a radius of 1.9 ± 0.4R ⊙. Its rotation velocity is 2 km s−1, which is a factor of 18 lower than the pseudo-synchronous velocity for this component. The G6 secondary component, a T Tau star, has a rotation velocity of 17 km s−1, amass of 1.1M ⊙, and a radius of 1 R ⊙. The age of the binary has been estimated to be 107 yr.  相似文献   

7.
New BV light curves of the A-type W UMa star AQ Psc (P = 0.476d) have been observed and are described. A few times of minimum light are obtained and the ephemeris is improved. The light curves are analyzed for the binary parameters with a light curve synthesis method. Combining the results with Lu and Rucinski’s spectroscopic mass ratio we determined the masses and radii of the components: M 1 = 1.69M ⊙, M 2 = 0.38M ⊙, R 1 = 1.77R ⊙, and R 2 = 0.89R ⊙.  相似文献   

8.
Cross correlations between observed and synthetic spectra are used to discover yet another satellite of BM Ori with the following characteristics: effective temperature Teff = 4000 K, radius R = 16R⊙, mass M = 1.8M⊙, spectral type K7 III, absolute bolometric stellar magnitude Mb = + 4m·0, axial rotation velocity V sini = 85 km/s, and relative luminosity 0.005 near the V band. __________ Translated from Astrofizika, Vol. 49, No. 1, pp. 111–120 (February 2006).  相似文献   

9.
In this study complete BV light curves of the W Ursae Majoris binary V1073 Cygni obtained in 2005 are presented. We have used the spectroscopic data of V1073 Cyg obtained by Ahn et al. (1992) for analysis. The analysis of radial velocity and light curves was made with Wilson} program (1998) and the geometric and physical elements} of the system were derived. By searching the simultaneous} solutions of the system, we have determined the masses and radii of the components: 1.64M⊙, 2.275R⊙ for the primary component and 0.55M⊙, 1.397R⊙ for the secondary component respectively. The effective temperature of 6494 ± 53 K for the secondary component was also estimated.  相似文献   

10.
We present the results of our infrared observations of WR 140 (=V1687 Cyg) in 2001–2010. Analysis of the observations has shown that the J brightness at maximum increased near the periastron by about 0 m .3; the M brightness increased by ∼2 m in less than 50 days. The minimum J brightness and the minimum L and M brightnesses were observed 550–600 and 1300–1400 days after the maximum, respectively. The JHKLM brightness minimum was observed in the range of orbital phases 0.7–0.9. The parameters of the primary O5 component of the binary have been estimated to be the following: R(O5) ≈ 24.7R ⊙, L(O5) ≈ 8 × 105 L ⊙, and M bol(O5) ≈ −10 m . At the infrared brightness minimum, T g ∼ 820–880 K, R g ≈ 2.6 × 105 R ⊙, the optical depth of the shell at 3.5 μm is ∼5.3 × 10−6, and its mass is ≈1.4 × 10−8 M ⊙. At the maximum, the corresponding parameters are ∼1300 K, 8.6 × 104 R ⊙, ∼2 × 10−4, and ∼6 × 10−8 M ⊙; the mean rate of dust inflow (condensation) into the dust structure is ∼3.3 × 10−8 M ⊙ yr−1. The mean escape velocity of the shell from the heating source is ∼103 km s−1 and the mean dispersal rate of the shell is ∼1.1 × 10−8 M ⊙ yr−1.  相似文献   

11.
A catalog of massive (⩾10 M ⊙) stars in binary and multiple systems with well-known masses and luminosities has been compiled. The catalog is analyzed using a theoretical mass-luminosity relation. This relation allows both normal main-sequence stars and stars with peculiarities: with clear manifestations of mass transfer, mass accretion, and axial rotation, to be identified. Least-squares fitting of the observational data in the range of stellar masses 10M ⊙ ⩽ M ≲ 50 M ⊙ yields the relation L ∼ M 2.76. An erratum to this article is available at .  相似文献   

12.
I review recent results concerning the metal enrichment of the intergalactic medium and give arguments which allow to conclude that the heavy elements detected in the Lyα forest absorbers must have been produced and injected by a population of protogalaxies with typical mass ≈ 108 M⊙ at redshift z ≈ 10. In addition, I will discuss the existence of a metallicity-induced shift in the Initial Mass Function of first stars from an extrely top-heavy distribution to a `normal' one and bring observational support to this idea. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

13.
Following our hypothesis that each supernova (SN) event triggers star formation in the swept-up gas, so that newly formed stars inherit the elemental abundance pattern of individual SNe, we deduce the production sites and yields for r-process elements. We further show that a strong evidence for the origin of r-process nucleosynthesis products was just there in our backyard - supernova SN1987A -, and conclude that 20 M ⊙ SNe are the predominant production sites for r-process elements. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

14.
TheUBV light curves obtained by Duerbeck (1975) andHa (wide) and Ha (narrow) light curves obtained by Chambliss & Davan (1987) of the detached eclipsing binary VV Orionis (VV Ori) were analysed using the Wilson-Devinney method fixing the two parametersT h (25,000 K) and q(0.4172), resulting in the following absolute elements:A = 13.605 ± 0.03 LR⊙,R h = 5.03 ±0.03R ⊙, Rc = 2.43 ±0.02R ⊙,M bol,h = -5.18 ± 0.11,M bol,c = -1.54 ± 0.06,m h =10.81 + 0.42m ⊙ andm c = 4.51 ± 0.41m ⊙. The de-reddened colours obtained from applying the reddening corrections ofE(B-V) = 0m.05 andE(U-B) = O m .04, and the derived temperatures of the components, gave spectral types ofB 1.5V for the primary and 54-5V with anUV excess of 0 m ·3 for the secondary component. A comparison of the logL and logT e of the components with the observed ZAMS shows the primary component to be a little above and the secondary component to be a little below/or on the ZAMS. A comparison of the properties of the components of VV Ori and a few other detached systems with the normal stars in the logL, logR and logT e versus logm planes, indicated a need for either a readjustment of the scales of the above parameters or modifications in the theoretical models. From the position of the components on the evolutionary tracks of Pop I composition computed by Schaller et al. (1992) it is noticed that while the primary component of W Ori had slightly evolved along the main-sequence, its secondary is still unevolved. The age of VV Ori is found to be 10 ± 1 million years and it is at a distance of 368 ± 10 pc.  相似文献   

15.
We present the results of a search for companions around the isolated galaxies from the 2MIG catalog. Among 3227 2MIG galaxies we detected 125 objects with a total of 214 neighbors having radial velocity differences of ΔV < 500 km/s and projected separations of R p < 500 kpc relative to the 2MIG galaxies. The median luminosity of the companions is 1/25 of the luminosity of catalog galaxies, which has little effect on the dynamic isolation of the latter. The median ratio of the orbital mass to the K-luminosity determined from 60 companions of E and S0 2MIG galaxies, 63M ⊙/L ⊙, is significantly greater than that found from the spiral galaxy companions (17M ⊙/L ⊙). We note that a fraction of 2MIG galaxies with companions may be a part of low-contrast diffuse structures: clouds and filaments.  相似文献   

16.
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17.
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   

18.
Model atmosphere analysis, based on Kurucz models has been applied to study the F6V star π3 Ori (=BS1543=HD30652). The following values of the effective temperature, surface gravity and microturbulence velocity were obtained: = 6270±200 K, log g = 3.80.2, ξt =3.5±0.5 km/s. The abundances of 10 elements were determined. The resulting element abundances for the π3 Ori were found to be about three times lower with respect to the Sun. From evolutionary calculations we derived a mass, radius and luminosity for π3 Ori of M =1.3 M⊙, R =2.38 R⊙, L =7.9 L⊙. Hence this star should be classified F6IV instead of F6 V. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

19.
The Hipparcos Space Astrometry Mission photometric observations of V398 Lac, led to the discovery of its variability, allowing to classify it as an eclipsing binary with an orbital period of about 5.4 days. This prompted us to acquire highresolution échelle spectra with the aim of performing accurate radial velocity measurements and to determine the main physical parameters of the system's components. We present, for the first time, a double‐lined radial velocity curve and determine the orbital and physical parameters of the two components, that can be classified both as late B‐type stars. In particular, we obtained an orbital inclination i ∼ 85°. With this value of the inclination, we deduced masses M1 = 3.83±0.35 M⊙ andM2 = 3.29±0.32 M⊙, and radii R1 = 4.89±0.18 R⊙ and R2 = 2.45±0.11 R⊙ for the more massive and less massive components, respectively. Both components are well inside their own Roche lobes. The mass ratio is M2/M1 ∼ 0.86. We derived also the projected rotational velocities as v1 sin i = 79±2 km s–1 and v2 sin i = 19±2 km s–1. Our measurements indicate that the rotation of the primary star is essentially pseudo‐synchronized with the orbital velocity at the periastron, while the secondary appears to rotate very slowly and has not yet attained synchronization. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

20.
New Claret evolutionary model-tracks, constructed for the first time for studying close binary systems (CBS) including tidal evolution constants, are used to determine the age of 112 eclipsing-variable stars in the Svechnikov-Perevozkina catalog by the method of isochrones. There is some interest in comparing the calculated ages with previous estimates obtained for these same close binary systems using evolutionary modeltracks for individual stars taking their mass loss into account. A correlation of the ages of the principal and secondary components is noted, which is most marked for massive close binaries with principal components having masses M1 ≥ 3 M⊙. A rejuvenating effect is found to occur for the systems studied here as calculated on the new tracks; it is most distinct for low-mass close binaries with a total mass M1 + M2 ≤ 3.5 M⊙ and is predicted theoretically in terms of magnetic braking. The calculated broadband grid of isochrones, from zero-age main-sequence (ZAMS) to the age of the galaxy, can be used for estimating the ages of close binaries from other catalogs. Ages are given for the 112 eclipsing-variable close binaries with detached components lying within the main sequence. __________ Translated from Astrofizika, Vol. 50, No. 2, pp. 299–312 (May 2007).  相似文献   

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