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1.
Intensified Reticon spectra have been obtained at a high dispersion for the Algol system, RT Persei. They were measured by the cross-correlation technique. The spectroscopic elements, revised for the primary component and determined for the secondary for the first time, are: T0 = HJD 2,446,038.9332, K1 = 55.0, K2 = 194.7, V0 = −8.3 km/s. A mass ratio q = m2/m1 = 0.282 is deduced. A circular orbit is adopted. The spectrum of the primary is F5V, and the secondary is a subgiant. With the elements determined here and the published photometric parameters, the absolute dimensions of the binary are: A = 4.20, R1 = 1.20, R2 = 1.08 R; M1 = 1.08, M2 = 0.30 M.  相似文献   

2.
From the photometric and spectroscopic data on AA UMa obtained by us in 1987 and 1986 and using the Wilson-Devinney program, we made a simultaneous solution. We found mass-ratio q = 1. 8157 ± 0.0099, M1 = 0.85 M, M2 = 1. 55 M , A = 3.39 R , R1 = 1.50 R , and degree of over-contact f = 0.15 ± 0.01. Adding six minimum times obtained by us to the literature, a new epoch formula is derived: Min.I(J.D.Hel) = 2 446 885.1119+0.468 125 83 E.  相似文献   

3.
Using the proper motion and parallax data for 1011 O-B stars in the Hipparcos Catalogue we have derived the Oort constants, A = 17.60 ± 0.21 (km/s)/kpc, B = −14.62 ± 0.20 (km/s)/kpc, and a solar velocity V = 16.7 ± 0.10 km/s in the direction l = 45.3° ± 2.8°, b = 21.0° ± 2.3°. For a galactocentric distance of the sun of R0 = 8.5 kpc, we then get a galactic rotational velocity of the solar neighbourhood of Vlsr = 273.9 km/s, obviously much higher than the IAU published value of 220 km/s. We have investigated the cause for this difference.  相似文献   

4.
On the basis of radial velocity and Hipparcos proper motion data, we have analyzed the galactic kinematics of classical Cepheids. Using the 3-D Ogorodnikov-Milne model we have determined the rotational velocity of the Galaxy to be V0 = 240.5 ± 10.2 km/s, on assuming a glactocentric distance of the Sun of R0 = 8.5 kpc. The results clearly indicate a contracting motion in the solar neighbourhood of (∂Vθ∂θ)/R = −2.60 ± 1.07 km s−1 kpc−1, along the direction of galactic rotation. Possible reason for this motion is discussed. The solar motion found here is S = 18.78 ± 0.86 km/s in the direction l = 54.4° ± 2.9° and b = +26.6° ± 2.6°.  相似文献   

5.
We further discussed the Modified Mean Field Theory proposed in [1,2]. We found that this model has a new solution ml = 2; adding -meson, we calculated the symmetric energy of nuclear matter a4; with the new parameters we calculated the equations of state with and without the addition of -meson; we compared the two; we also compared with the results for ml = 4.3; we made a preliminary theoretical investigation of the form of the vector meson mean field using the two-body correlation function; lastly, using the structural equation of neutron star we calculated the maximum mass for the various equations of state. The results are:
MMFT-2 (ml = 2): Mmax = 2.22M (without -meson) Mmax = 2.27M (with -meson)
MMFT-1 (ml = 4.3): Mmax = 1.69M (without -meson) Mmax = 1.89M (with -meson)
  相似文献   

6.
We present our 1984 radial velocity observations of the W UNa system SW Lac. These give a new spectroscopic mass ratio qsp = 1.255 ±0.011. A joint solution of the velocity and light curves give the following revised absolute parameters: M1 = 0.78 M, M2 = 0.96M, R1 = 0.91R, and R2 = 1.00 R. Based on our new results, together with a detailed review of the period changes, probable mass transfer, mass loss, spot activity and other physical properties of SW Lac are discussed.  相似文献   

7.
Using a complete non-local convection theory, we carried out the theoretical calculations of 7Li depletion of the solar convective envelope models with different convective parameters c1 and c2, and got a model of the solar convection zone consistent with the observed 7Li abundance and the depth of the solar convection zone determined by helioseismic techniques. The overshooting distance of effective non-local convective mixing of 7Li is very extensive, which is about 1.07HP or 0.09R. However, the super-radiative temperature zone is much narrower, and it is only 0.20HP or 0.016R.  相似文献   

8.
It is greatly expected that the relic neutrino background from past supernovae will be detected by Superkamiokande (SK) which is now under construction. We calculate the spectrum and the event rate at SK systematically by using the results of simulations of a supernova explosion and reasonable supernova rates. We also investigate the effect of a cosmological constant, Λ, on the spectrum, since some recent cosmological observations strongly suggest the existence of Λ. We find following results. (1) The spectrum has a peak at about 3 MeV, which is much lower than that of previous estimates (6–10 MeV). (2) The event rate at SK in the range from 10 MeV to 50 MeV, where the relic neutrinos from past supernovae are dominant, is about 25h502(RSN/0.1 yr−1)(nGh50−3/0.02 Mpc−3) events per year, where RSN is the supernova rate in a galaxy, nG is the number density of galaxies, and h50 = H0/(50 km/s Mpc), where H0 is the Hubble constant. (3) The event rate is almost insensitive to Λ. The flux increases in the low energy side (< 10 MeV) with increasing Λ, but decreases in the high energy side (> 10 MeV) in models in which the integrated number of supernovae in one galaxy is fixed.  相似文献   

9.
We report intermediate resolution H spectroscopy of the black hole candidate Nova Muscae 1991 during quiescence. We classify the companion star as a K3-K4V which contributes 85±6 percent to the total flux from the binary. The photospheric absorption lines are broadened by 106±13 kms−1 with respect to template field stars, leading to a system mass ratio of q =M1/M2 = 7.8−2.0+3.4. Doppler imaging of the H line shows strong emission coming from the secondary star (EW=3.1±0.6Å) which we associate with chromospheric activity. However, the hot-spot is not detected and this may indicate a lower mass transfer rate than in other X-ray transients of comparable orbital periods. The surface brightness distribution of the accretion disk in H follows a relation I∝R−1.1, less steep than typically observed in cataclysmic variables. Updated system parameters are also presented.  相似文献   

10.
Auroral luminosities of the main emission lines in the aurora have been calculated for excitation by an isotopic primary electron flux with spectra of the form J(E) = AE exp (−E/E1) + B(E2)E exp (−E/E1). The variation of emissions from O and N2+ with height are shown, as are the variations of column integrated intensities and pertinent intensity ratios with the characteristic energy E2, this leading to a method of estimating the electron spectrum from ground observation.  相似文献   

11.
The global structure of accretion disks is investigated in a unified scheme. We use a general radiative cooling formula applicable to both optically thick and thin regimes and we include radial advection cooling. Within the -viscosity models, we found distinct families of global solutions. If the accretion rate is low, there are three non-intersecting solutions, corresponding to optically thick and thin, local cooling and optically thin advection cooling. If the accretion rate is high, and the viscosity coefficient is large, the two local cooling solutions coincide at radii R1 and R2 and exist independently below R1 and above R2 while the advection solution is stable at all radii. If the accretion is high and the viscosity is low, the two optically thin solutions will cross each other while the optically thick solution exists at all radii.  相似文献   

12.
The method of identifying absorption line systems in QSO spectra (Cui et al. 1983; Chen et al. 1983) is further developed here. Certain limitations of the method and their improvements are discussed. Certain other problems requiring further study are pointed out. The improved method is applied to PKS 0528-250, and gives two new absorption line systems Za = 0.065 and 0.0345 in addition to the four systems Za = 2.8110, 2.8130, 2.5275, 2.1410, consistent with the systems A1A2, B, C of Norton et al. (1980). However, the systems D1, D2, E, F and G of Chen and Norton (1984) are not recovered. The reason for this discrepancy is discussed.  相似文献   

13.
In this paper we have analysed the effect of the lunar tide on the latitude observations of 25260 star-pairs with the zenith telescope, ZTL-180 of Tianjin Latitude Station during 1960–1966. For the M2 wave, we found an amplitude of 0.0108 and hence a value of 1 + k − 1 = 1.34. When the effect of the ocean tide is subtracted, the value of 1 + k − 1 is reduced to 1.315. This is in very good agreement with the value 1.31, deduced by geophysicists for the Asia region.  相似文献   

14.
High-resolution spectroscopic observations around the Hα line and BVRI photometry of the eclipsing short-period RS CVn star UV Leo are presented. The simultaneous light-curve solution and radial velocity-curve solution led to the following values of the global parameters of the binary: temperatures   T 1= 6000 ± 100 K  and   T 2= 5970 ± 20 K  ; masses   M 1= 0.976 ± 0.067 M⊙  and   M 2= 0.931 ± 0.052 M⊙  ; separation   a = 3.716 ± 0.048 R⊙  ; orbital inclination     ; radii   R 1= 1.115 ± 0.052 R⊙  and   R 2= 1.078 ± 0.051 R⊙  ; equatorial velocities   V 1= 98.8 ± 2.3 km s−1  and   V 2= 89.6 ± 2.7 km s−1  . These results lead to the conclusion that the two components of UV Leo are slightly oversized for their masses and lie within the main-sequence band on the mass–radius diagram, close to the isochrone 9 × 1010 yr.  相似文献   

15.
The 'All Sky Automated Survey' (ASAS) photometric observations of LS 1135, an O-type single-lined binary (SB1) system with an orbital period of 2.7 d, show that the system is also eclipsing performing a numerical model of this binary based on the Wilson–Devinney method. We obtained an orbital inclination     . With this value of the inclination, we deduced masses   M 1∼ 30 ± 1 M⊙  and   M 2∼ 9 ± 1 M⊙  , and radii   R 1∼ 12 ± 1 R⊙  and   R 2∼ 5 ± 1 R⊙  for primary and secondary components, respectively. Both the components are well inside their respective Roche lobes. Fixing the T eff of the primary to the value corresponding to its spectral type (O6.5V), the T eff obtained for the secondary component corresponds approximately to a spectral type of B1V. The mass ratio   M 2/ M 1∼ 0.3  is among the lowest known values for spectroscopic binaries with O-type components.  相似文献   

16.
N. Hiotelis   《New Astronomy》2002,7(8):531-539
We present density profiles, that are solutions of the spherical Jeans equation, derived under the following two assumptions: (i) the coarse grained phase-density follows a power-law of radius, ρ/σ3 ∝ r−, and (ii) the velocity anisotropy parameter is given by the relation βa(r)=β1+2β2 (r/r*)/[1+(r/r*)2] where β1, β2 are parameters and r* equals twice the virial radius, rvir, of the system. These assumptions are well motivated by the results of N-body simulations. Density profiles have increasing logarithmic slopes γ, defined by γ=−d ln ρ/d ln r. The values of γ at r=10−2.5rvir, a distance where the systems could be resolved by large N-body simulations, lie in the range 1.0–1.6. These inner values of γ increase for increasing β1 and for increasing concentration of the system. On the other hand, slopes at r=rvir lie in the range 2.42–3.82. A model density profile that fits well the results at radial distances between 10−3rvir and rvir and connects kinematic and structural characteristics of spherical systems is described.  相似文献   

17.
Observations, from the Apollo 16 Spacecraft, in lunar orbit, of the total radiance of the K + F corona, from 3 R to 55 R are presented and discussed.

The logarithmic slope of the K + F coronal radiance, in the region r > 20 R, is found to be n = 1.93, slightly less steep than previous determinations. The photometric axis of the radiance is found to be displaced 3 ± 1° north of the ecliptic, for the region r > 20 R, and this displacement is interpreted as an annual variation due to non-coincidence of the ecliptic and the symmetry axis of the zodiacal cloud.  相似文献   


18.
The time sequence of 105 spectra covering one full orbital period of AA Dor has been analysed. Direct determination of   V  sin  i   for the sdOB component from 97 spectra outside of the eclipse for the lines Mg  ii 4481 Å and Si  iv 4089 Å clearly indicated a substantially smaller value than estimated before. Detailed modelling of line-profile variations for eight spectra during the eclipse for the Mg  ii 4481 Å line, combined with the out-of-eclipse fits, gave   V  sin  i = 31.8 ± 1.8 km s−1  . The previous determinations of   V  sin  i   , based on the He  ii 4686 Å line, appear to be invalid because of the large natural broadening of the line. With the assumption of the solid-body, synchronous rotation of the sdOB primary, the measured values of the semi-amplitude K 1 and   V  sin  i   lead to the mass ratio   q = 0.213 ± 0.013  which in turn gives K 2 and thus the masses and radii of both components. The sdOB component appears to be less massive than assumed before,   M 1= 0.25 ± 0.05 M⊙  , but the secondary has its mass–radius parameters close to theoretically predicted for a brown dwarf,   M 2= 0.054 ± 0.010 M⊙  and   R 2= 0.089 ± 0.005 R⊙  . Our results do not agree with the recent determination of Vŭcković et al. based on a K 2 estimate from line-profile asymmetries.  相似文献   

19.
The MSX infrared dark cloud G79.2+0.38 has been observed over a 11′×′ region simultaneously in the J=1-0 rotational transition lines of the 12CO and its isotopic molecules 13CO and 18CO. The dense molecular cores defined by the C18O line are found to be associated with the two high-extinction patches shown in the MSX A-band image. The two dense cores have the column density N (H2) (5 – 12) × 1022 cm−2 and the mean number density n (3 ± 1) × 104 cm−3. Their sizes are 1.7 and 1.2 pc in 13CO(1-0) line, 1.2 and 0.6 pc in C18O(1-0) line, respectively. The masses of these cloud cores are estimated to be in the range from 2 × 102 to 2 × 103 M. The profile of radial mean density of the cloud core can be described by the exponential function ¯n(p) p−0.34±0.02. Compared with the cases of typical optical dark clouds, the abundances of the CO isotopic molecules 13CO and C18O in this MSX infrared dark cloud appear to be depleted by a factor of 4–11, but at present there is no evidence for any obvious variation of the relative abundance ratio X13/18 between 13CO and C18O with the column density.  相似文献   

20.
The concept of Roche lobe overflow is fundamental to the theory of interacting binaries. Based on potential theory, it is dependent on all the relevant material corotating in a single frame of reference. Therefore if the mass losing star is asynchronous with the orbital motion or the orbit is eccentric, the simple theory no longer applies and no exact analytical treatment has been found. We use an analytic approximation whose predictions are largely justified by smoothed particle hydrodynamic simulations (SPH). We present SPH simulations of binary systems with the same semi-major axis   a = 5.55 R⊙  , masses   M 1= 1 M⊙, M 2= 2 M⊙  and radius   R 1= 0.89 R⊙  for the primary star but with different eccentricities   e = 0.4, 0.5, 0.6  and 0.7. In each case the secondary star is treated as a point mass. When   e = 0.4  no mass is lost from the primary while at   e = 0.7  catastrophic mass transfer, partly through the L2 point, takes place near periastron. This would probably lead to common-envelope evolution if star 1 were a giant or to coalescence for a main-sequence star. In between, at   e ≥ 0.5  , some mass is lost through the L1 point from the primary close to periastron. However, rather than being all accreted by the secondary, some of the stream appears to leave the system. Our results indicate that the radius of the Roche lobe is similar to circular binaries when calculated for the separation and angular velocity at periastron. Part of the mass loss occurs through the L2 point.  相似文献   

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