Photoelectric study of the δ Scuti star HR 1225

The periodogram analysis of theV observations of the Scuti star HR 1225 has been carried out. Two frequencies of 6.415 cd (P ₀=0 _. ^d 1558) and 8.418 cd (P ₁=0 _. ^d 1188) have been determined. The period ratio ofP ₁/P ₀=0.762 indicates radial pulsation. The absolute magnitude, effective temperature and mass of the star are derived to be 1 _. ^m 05, 7600 K and 1.9M , respectively.     

Three Periods in Asteroid 4197 Brightness Variations

In 1996, photometric observations of the near-Earth asteroid NEA 4197 (1982 TA) were performed at the Crimean Astrophysical Observatory. More than 2000 brightness measurements in the V band were made. The harmonic data analysis at a fairly high significance level revealed two close periods, P ₁= 3^h _.5372 ± 0^h _.0005 (amplitude 0 ^m _.4) and P ₂= 4^h _.367 ± 0^h _.001 (amplitude 0 ^m _.2). The third period, P ₃= 20^h _.26 ± 0^h _.05 (amplitude about 0 ^m _.15), was found at a lower significance level. The conclusion was drawn that the asteroid is a binary system. Its components rotate with the periods P ₁and P ₂, and P ₃is probably related to the orbital motion of the components. Assuming that the diameters of both components are equal to 2 km, the orbital radius equals 4.4 km.     

V792 Her=HD 155638: A totally eclipsing RS CVn binary

Photometry of HD 155638=V792 Her has been analyzed to determine the elements of this totally eclipsing RS CVn binary. The light variation outside eclipse was found to have a period of 27^d.07±0^d.07, which is slightly different from the 27^d.5384±0^d.0045 orbital period. Analysis of the eclipses was achieved by a modification of the Russell-Merrill technique. With the aid of radial velocity measures, absolute elements were obtained for the hot and cool stars, respectively;R _h=2.58R ,R _c=12.28R ,M _h=1.40M ,M _c=1.46M ,i=80^o.61 and velocity semi-amplitudesK _c=48.36 km s^–1±0.79 km s^–1, andK _h=50.50 km s^–1±0.33 km s^–1. The apparent magnitudes areV _h=9 ^m .73 andV _c=8 ^m .48. The distance to HD 155638 was estimated to be 310 parsecs.     

Pulsation periods in theδ Scuti star HR 1170

All knownV data from the literature for the Scuti star HR 1170 have been reanalysed by using single-frequency Fourier and multiple-frequency least squares analysis. The calculated periods areP ₁=0 _. ^d 09942 andP ₂=0 _. ^d 08392. The second frequency has not been found before and gives better residuals and almost constant amplitudes for the individual data sets. The period ratio andQ values indicate that this star is not pulsating in pure radial modes.     

Determination of the mass-ratio distribution,I: Single-lined spectroscopic binary stars

For single-lined spectroscopic binary stars (SBI), the mass ratioq=M _sec/M _prim is calculated from the mass functionf(m), which is determined from observations. For statistical investigations of the mass-ratio distribution, the term sin³ i, that remains in the cubic equation from whichq is solved, has to be dealt with.This paper compares the common practise of taking an average value for sin³ i to a deconvolution scheme that takes into account the precise (expected) behaviour ofP (sin³ i) d sin³ i. The behaviour ofP(sin³ i) d sin³ i depends on how orbital planes of binary stars are oriented in space. For a random orientation of orbital planes,P _i(i) di=sini di. For the average value method, it is generally assumed thatP _i(i) di=(4/) sin² i di.For verification purposes, the deconvolution scheme is applied to an observed sample of double-lined spectroscopic binary stars (SBII), and to a synthetic sample of SBI systems, produced by a numerical model. In both cases, the scheme produces better results with the assumption thatP _i(i) di=(4/gp) sin² i di, rather than a purely random orientation of orbital planes. In the case of the synthetic sample of SBI systems, the deconvolution scheme does not produce better results than the method that assumes an average value for sin³ i.Application of the deconvolution method to the double-lined spectroscopic binary systems in theEighth Catalogue of the Orbital Elements of Spectroscopic Binary Stars, provides results which are compatible with the assumption that the orbital planes of these systems are oriented randomly in space.     

54 Cam: A new variable star

Differential photometry of the RS CVn-type binary 54 Cam in 1978, 1979, and 1980 shows its light to be variable with a period of 10 _. ^d 163±0 _. ^d 009 and an amplitude inV (max. to min.) which increased from 0 _. ^m 03 to 0 _. ^m 06 between 1979.19 and 1980.82. An epoch of light minimum was JD 2444529.7. The 9% difference betweenP(phtm.)=10 _. ^d 163 andP(orb.)=11 _. ^d 0764,a much larger difference than is characteristic of other RS CVn binaries, is suggested as an explanation for the radio emission.Guest Investigator, Kitt Peak National Observatory,which is operated by the Association of Universities for Research in Astronomy, under contract with the National Science Foundation.Of the AAVSO.     

U - B - V photometry of the spectroscopic-visual triple HD 165590

HD 165590 is a visual binary (dG0 + dG5,P = 20 _. ^y 25,e = 0.96) whoseA component is an SB1 double (dG5 + dM:P = 0 _. ^d 88,e0.0). TheA pair (Aa +Ab) undergoes partial eclipses. PhotoelectricUBV photometry from Lines and one of the Automatic Photoelectric Telescopes, andV photometry from Scarfe are examined here. The data are from the 1977, 1984, 1985, and 1986 observing seasons. The non-eclipse light variations are analyzed with a FORTRAN program which does a sinusoidal curve fitvia least squares repeatedly to obtain the best period. Periods found from each observing season and passband are consistent with Boydet al. (1985): the greatest variations seem to be produced by a rotating (0 _. ^d 88), spotted, G0 star (theAa component). To the residuals from the first analysis a further curve fit is made to determine characteristics of the wave due to the ellipticity effect. An early limit on the spectral type of the unseenAb component, based on the primary eclpse depth and the upper limit on the depth of the unseen secondary eclipse, is K2. Eclipse depths and widths seen here suggest that theA pair's inclination = 74 _. ⁰ 9 ± 1⁰, close to theA +B inclination of 82 _. ⁰ 7 ± 2⁰ (Battenet al., 1979). TheA pair's orbital period does not appear to vary, appearing instead to be well-described by a new linear ephemeris (Hel. J.D. = 2443665.4568 + 0 _. ^d 8795045E) which does, however, take into account a variable light-travel-times as theA component orbits theA +B center of mass with a 20 _. ^y 25 period. The maximum light-travel-time O-C thus produced is + /–8 _. ^m 4 = + /–0 _. ^d 0059.     

Apsidal motion in the eclipsing binary system of BW AQR

The first photoelectric light curve of the eclipsing binary system BW Aqr (F71V+F81V;P=6^d.7;V=10 ^m .31), discovered by Miss Leavitt at the beginning of the century, was obtained. The photometric elements were detemined. The components of this system are considerably evolved stars: the age of the system is about 2×10⁹ yr. It follows from the photometric data that the secondary component should have greater mass than the primary one The zero-age spectral classes of components were F2V and F1V. The system has an elliptical orbit with the eccentricitye=0.18. The angular rate of the apsidal motion (_obs = 0.070 deg yr^–1) and the corresponding value of the apsidal parameterk ₂=0.0090 (the relativistic term included) were found. The derived valuek ₂ exceeds by more than a factor of 2 the theoretical coefficient obtained from the modern theory of internal structure of stars with moderate masses .     

MM Herculis: An eclipsing binary of the RS CVn type

Differential photoelectric photometry inV, B, andU has been obtained for the eclipsing binary MM Her, a member of the RS Canum Venaticorum class. The light outside eclipse was Fourier-analyzed to study the wave. The migration and amplitude of the wave and the mean light level of the system now have been monitored from 1976 through 1980. The phase of wave minimum has decreased from 0 _. ^P 80 to 0 _. ^P 25, the wave amplitude has varied between 0 _. ^m 06 and 0 _. ^m 12, and the mean light level has fluctuated between 0.94 and 0.99. Observations within eclipse revealed that the eclipses are partial, not total as previously thought, and a new time of mid-eclipse was found to be JD (hel.)=2444 500.6665±0 _. ^d 0008. The Russell model was used to solve the 1980 light curve. Elements of the rectified light curve werei=86 _. ^° 35±0 _. ^° 09,r _h =0.070±0.002,r _c =0.125±0.001,L _h (V)=0.585±0.008 andL _h (B)=0.683±0.010. The geometric elements were forced on the pre-1980 light curves and found to be compatible. With these elements and previously obtained double-lined radial velocity curves, new absolute dimensions have been calculated: 1.18M and 1.58R for the hotter star and 1.27M and 2.83R for the cooler star. By plotting color indices on the color-color curve, spectral types of G2V and K21V were found, each uncertain by a couple of subclasses.Guest Observer Kitt Peak National Observatory, operated by the Association of Universities for Research in Astronomy, under contract with the National Science Foundation.     

VR c photometry of dwarf cepheids (I)

In this paper, we present VRc photometric observations of four dwarf cepheids: YZ Boo (P = 0 _. ^d 104, V = 0 _. ^m 5), AD CMi (P = 0 _. ^d 123, V = 0 _. ^m 5), XX Cyg (P = 0 _. ^d 135, V = 0 _. ^m 5), EH Lib (P = 0 _. ^d 088, V = 0 _. ^m 7). The light curves were obtained at West Mountain Observatory, Provo, Utah on 14 nights from 1983 through 1986 and contain 589 data points in each of theV andR bands in the Cousin photometric system. A detailed study of these stars, based on the present light curves, will be published separately.     

Physical studies of asteroids IX: The light curve of the M asteroid 77 Frigga

The results of photoelectricUBV observations of asteroid 77 Frigga during the 1982 opposition are presented. From eight nights of observations at phase angles smaller than 2 _o ^. 8 a synodic period of 0 _d ^. 3755±0 _d ^. 0006 is derived. The light curve appears very symmetric with two maxima per period and an amplitude of 0 _m ^. 19. The primary maximum corresponds toV(0^o)=8 _m ^. 58, and the colour indices are:B–V = 0 _. ^m 738 ± 0 _. ^m 003 andU–B = 0 _. ^m 200 ± 0 _. ^m 002.     

Evolution of starspot regions in DM UMa

B andV photometry of DM UMa obtained between January, 1980 and June, 1984 is presented. Analysis yields a mean photometric period 7^d.478±0^d.010, compared to the known oribital period of 7^d.492±0^d.009. Light curves obtained during any two seasons do not agree in any of the following: shape, amplitude, phases of the light maxima and minima, mean light level, or brightness at the light maxima and minima. From the change inB-V over the photometric period, we concludethat the hemisphere visible during the light minimum is cooler than that seen during light maximum. The mean colorB-V=1^m.065±0^m.002 is consistent with K1 III or K2 IV. Phases of light minima lie on two well-separated groups with different slopes; the corresponding periods are 7^d.471±0^d.002 and 7^d.481±0^d.001, in dicating that both migrate linearly towards decreasing orbital phase. In terms of the starspot model this indicates that two respective centers of activity were situated at different longitudes and latitudes on a differentially rotating star. From circumstantial evidence we infer that the dark region seen from 1979 onwards disintegrated sometime between the 1982 and 1983 observing seasons, leaving behind an area of relatively high surface brightness. We can put a lower limit of about four years on the lifetime of a center of activity.     

Interpretation of the underground muon charge ratio

The MINOS experiment has observed a rise in the underground muon charge ratio r_μ=μ⁺/μ^-. This ratio can be related to the atmospheric production ratios of π⁺/π^- and K⁺/K^-. Our analysis indicates that the relevant variable for studying the charge ratio is , rather than . We compare a simple energy dependent parameterization of the rise in the charge ratio with more detailed previously published Monte Carlo simulations and an analytical calculation. We also estimate the size of two previously neglected effects in this context: the charge sign dependency of the dE/dx in rock, and the energy dependence of heavy primaries on the derived K⁺/K^- ratio.     

An Investigation of the Physical Mechanisms of Orbital Period Variations of the Semidetached Binary UW Vir

The orbital period variations of the Algol-type semidetached binary UW Vir are analyzed. It is shown that in addition to a long-term rapid increase (dP/dt = + 1.37 × 10⁻⁶ day/year), its orbit period has a variation with the period of 62.3 years. Based on the basic physical parameters given by Brancewicz and Dworak in 1980, the physical mechanisms causing the orbital period variations are investigated. The analysis indicates that the periodical variation of orbital period can be interpreted by the light-travel time effect due to the presence of a third body with the mass of M₃ ≥ 0.94 M. As no observational information has been reported for this tertiary component, it might be a compact object (e.g., a white dwarf). The long-term increase of orbital period can be explained in terms of the mass transfer from the secondary to the primary component (dM₂/dt = 1.43 × 10⁻⁷ M/year). This is in agreement with the semidetached configuration of the system with a lobe-filling secondary component. But according to the evolution theory of binaries, the Algol-type semidetached binary UW Vir should be at the evolutionary stage of slow mass transfer on the nuclear-reaction timescale of the secondary component. However, the analysis shows that the timescale for the periodical variation of orbital period is much shorter than the nuclear-reaction timescale of the secondary component, but close to the thermodynamic timescale of the secondary. This reveals that: (1) This binary system is at the evolutionary stage of rapid mass transfer on the thermodynamic timescale of the secondary component; or (2) The circumstellar matter of the system makes a contribution to the rapid increase of orbital period via the angular momentum transfer.     

A period study of V450 Herculis

A detailed period study of the eclipsing binary system V450 Her has been presented. A new period (P= _. ^d 12724) has been given. The period changes in different portions of the O-C diagram, based on new period, have been estimated. The total period change ranges from 3.28×10^–6 d to 7.06×10^–5 d, which is appreciable.     

Luminosity and colour distribution in the interacting system NGC 7770-71

Detailed surface photometry for the SB(s)a galaxy NGC 7771 has been carried out in the blue spectral band. Isophotes, luminosity profiles, and photometric parameters are obtained from photographs collected with the 74 inch telescope of Kottamia Observatory, Egypt. The total apparent magnitudem _T =13.08 with maximum dimensions 3.6±0.5×2.7±0.5 (at threshold µ _m = 27.38 mag s^–2). The absolute magnitude isM _T =–21.70 if the distance is =90.2 Mpc. The major axis is in position angle =69°.5±1° and the mean axis ratio of the outer regionsq=b/a=0.45 corresponds to an inclinationi=66°. The equivalent effective radiusr _e ^* =0.29 and the effective surface brightness µ _e = 22.30 mag s^–2.The equivalent luminosity distribution has been decomposed into two main components, anr ^1/4 spheroid and an exponential disk. The total apparent magnitudes of the spheroidal and disk components are 14.36 and 13.48, which correspond to contributions of 31 and 69% to the total blue luminosity, respectively.     

Spectral investigation of some Be stars for NRP variability

Spectroscopic observations of the Be stars Eri, Oph, 66 Oph, and Ori for the period 1982–1988 are reported. The NRP hypothesis was verified on the ground of rapid line profile variability, radial velocities, and equivalent widths. The star Eri is pulsating in bothl=2 andl=8 with period 0 _. ^d 7. Pulsation in modesl=2 andl=4 are observed in Hei profiles of Oph for May 1982. For radial velocities has been obtained a period 0 _. ^d 913. The H and H lines of 66 Oph for April–August 1983 are in emission state with two clearly expressed components with intensity variations. All the parameters measured have the same period of variation — 0 _. ^d 025. For Ori variations in line profiles for component Ab have been observed and a period of 0 _. ^d 463 found for the radial velocities.     

The Cepheid impostor HD 18391 and its anonymous parent cluster

New and existing photometry for the G0 Ia supergiant HD 18391 is analyzed in order to confirm the nature of the variability previously detected in the star, which lies off the hot edge of the Cepheid instability strip. Small‐amplitude variability at a level of δV = 0.016 ± 0.002 is indicated, with a period of P = 123^d.04 ± 0^d.06. A weaker second signal may be present at P = 177^d.84 ± 0^d.18 with δV = 0.007 ± 0.002, likely corresponding to fundamental mode pulsation if the primary signal represents overtone pulsation (123.04/177.84 = 0.69). The star, with a spectroscopic reddening of E_B–V = 1.02 ± 0.003, is associated with heavily‐reddened B‐type stars in its immediate vicinity that appear to be outlying members of an anonymous young cluster centered ∼10′ to the west and 1661 ± 73 pc distant. The cluster has nuclear and coronal radii of r_n = 3.5′ and R_c = 14′, respectively, while the parameters for HD 18391 derived from membership in the cluster with its outlying B stars are consistent with those implied by its Cepheid‐like pulsation, provided that it follows the semi‐period‐luminosity relation expected of such objects. Its inferred luminosity as a cluster member is M_V = –7.76 ± 0.10, its age (9 ± 1) × 10⁶ years, and its evolutionary mass ∼19 M_⊙. HD 18391 is not a classical Cepheid, yet it follows the Cepheid period‐luminosity relation closely, much like another Cepheid impostor, V810 Cen (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Period study of IT Persei

A new period (P=1 _. ^d 533731) of the eclipsing binary system IT Persei has been given, which is based on all available times of minima. O-C diagrams of IT Persei, based on the period given in PPEN (1980) and based on the new period, have been given.Long-term period changes are not present in the system, however, some period fluctuations of the order of 10^–5d are seen around the years 1907, 1921, and 1933.     

Massive fluid spheres with isothermal cores

We can define some adiabatic exponents for neutron star cores. The equality of and ₃ leads to an equation of stateE=P ln(K/P) orP=K exp(–E/P). This equation has been solved alongwith equations for hydrostatic equilibrium for different physical conditions at the centre. The parameters of isothermal neutron star cores have been computed by taking surface densityE _a=2×10¹⁴ g cm^–3. ForP ₀=E ₀ the maximum mass and radius of neutron star core are 3.25M and 17.14 km, respectively.