First period analyses of five neglected Algol-type eclipsing binaries: TT And, V342 Aql, RW Cap, BZ Cas and TW Lac

We present the first study of the orbital period variations of five neglected Algol-type eclipsing binaries TT And, V342 Aql, RW Cap, BZ Cas and TW Lac, using their O–C diagrams gathered from all available times of eclipse minima. These O–C diagrams indicate that short term periodic variations superimposed on secular period increases as expected in mass transferring Algols. However, due to short time coverage of the data, the secular period increase is not clear in the case of BZ Cas and V342 Aql. The secular period increase is interpreted in terms of the combined effect of mass transfer between the components of the system and the mass loss by a stellar wind from the system. The mass transfer rates from the less massive secondary components to the more massive primaries for non-conservative cases would be about 10⁻⁷M/yr and 10⁻⁸M/yr for RW Cap and V342 Aql, respectively, and 10⁻⁹M/yr for TT And and TW Lac. Therefore, the Algol systems RW Cap and V342 Aql have the largest mass transfer rate, which could be in Case AB type, while those of the Algol systems TT And and TW Lac display the slow mass transfer rate and they could be in Case B type. The sinusoidal forms of the orbital period variations of all five Algol systems can be due to either by the light-time effects due to unseen components in these systems, or by the cyclic magnetic activity effects of the cool secondary components. The possible third bodies in all five Algol binaries would have masses larger than one solar mass. If these hypothetical large massive third bodies were normal stars, they should be detectable. Therefore, new photometric and spectroscopic observations of these systems and careful analyses of those data are required. Otherwise, the cyclic magnetic activity effects of the secondary components could be the basis of a working hypothesis in explaining the cyclic period variations of these systems.     

Observation and Study of the CO, CO, HCO and N2H Molecular Lines Towards IRAS 02232+6138

Using the 13.7 m millimeter-wave telescope at the Qinghai Station of Purple Mountain Observatory, we have made observations of ¹³CO, C¹⁸O, HCO⁺ and N₂H⁺ molecular lines towards IRAS 02232+6138. As the excitation density of the probe molecule increases from ¹³CO to HCO⁺, the size of the cloud core associated with IRAS 02232+6138 decreases from 2.40 pc to 0.54 pc, and the virial mass of the cloud core decreases from 2.2 × 10³M to 5.1 × 10²M. A bipolar molecular outflow is found towards IRAS 02232+6138. Using the power function n(r) ∝ r⁻ to fit the spatial density structure of the cloud core, we obtain the power-law index  = 2.3 − 1.2; and we find that, as the probed density increases, the power function becomes more flat. The abundance ratio of ¹³CO to C¹⁸O is 12.4 ± 6.9, comparable with the values 11.8 ± 5.9 for dark clouds and the values 9.0–15.6 for massive cores. The abundance of N₂H⁺ molecules is 3.5 ± 2.5 × 10⁻¹⁰, consistent with the value 1.0 − 5.0 × 10⁻¹⁰ for dark cloud cores and the value 1.2 − 12.8 × 10⁻¹⁰ for massive cores. The abundance of HCO⁺ molecules is 0.9 ± 0.5 × 10⁻⁹, close to the value 1.6 − 2.4 × 10⁻⁹ for massive cores. An increase of HCO⁺ abundance in the outflow region was not found. Combining with the IRAS data, the luminosity-mass ratio of the cloud core is obtained in the range 37–163(L/M). Based on the IRAS luminosity, it is estimated that a main-sequence O7.5 star is probably embedded in the IRAS 02232+6138 cloud core.     

Ionospheric electric field and current distribution associated with high altitude electric field inhomogeneities

A quantitative theoretical analysis of electric field and current distributions in the ionosphere is given assuming certain time variable convection field profiles at an altitude of 1250 km. A number of idealized assumptions regarding the ionospheric characteristics are defined and discussed. A qualitative discussion of a quasi-stationary configuration with an approximately curl free electric field is also given. Geomagnetically field aligned current densities i of the order 10⁻⁵−10⁻⁴A/m² are consistent with quite reasonable assumptions about the convection field E. Oscillations in E with periods of the order of 10 sec should readily be generated when σ is large. In the quasi-stationary case there may be a mechanism that strengthens and concentrates i locally under certain conditions. It is found that a number of recent high altitude observations of convection field reversals may be consistent with large potential drops along the magnetic field lines. The solutions obtained as well as some of the basic assumptions are compared with observations.     

Supernova remnants and the spiral structure of the Galaxy

A set of unit clouds of 10⁴ M randomly distributed between 3 and 7 kpc radii, move under the general gravitation of the galactic disk and their mutual gravitation. When the clouds collide they form loose aggregates or giant molecular clouds (GMC). Star formation rate is assumed to be proportional to the mass of the GMC. The more massive stars formed soon turn into supernovae, which in turn break up the GMC back into the unit clouds. After some 350 Myr a steady state is reached, in which the GMCs have a mass spectrum of gradient −1.6, and has the mass-radius relation M ∞ R², both in agreement with the observations. From our simulation we find there should be 775 ± 12 supernova remnants in our galaxy. The existence of spiral arms does not increase the production rate of supernova remnants, but it does make the GMCs to concentrate around them.     

Galactic kinematics derived from classical cepheids

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 (∂V_θ∂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°.     

Helioseismological constraint on solar axion emission

Helioseismological sound-speed profiles severely constrain possible deviations from standard solar models, allowing us to derive new limits on anomalous solar energy losses by the Primakoff emission of axions. For an axion-photon coupling g_ay 5 × 10⁻¹⁰ GeV⁻¹, the solar model is almost indistinguishable from the standard case, while g_ay 10 × 10⁻¹⁰ GeV⁻¹ is probably excluded, corresponding to an axion luminosity of about 0.20 L. This constraint on g_ay is much weaker than the well-known globular-cluster limit, but about a factor of 3 more restrictive than previous solar limits. Our result is primarily of interest to the large number of current or proposed search experiments for solar axions because our limit defines the maximum g_ay for which it is self-consistent to use a standard solar model to calculate the axion luminosity.     

Helium ions in the mid-latitude plasmasphere

An initial study of the behaviour of He⁺ ions in the mid-latitude plasmasphere is carried out by solving the time-dependent equations of continuity and momentum. Starting with a low He⁺ tube content, results are obtained for a period of 8 days. In the topside ionosphere there is an upflow of He⁺ during the day and downflow at night, for the sunspot maximum conditions considered. The downflow at night differs from the behaviour of H⁺ for these atmospheric conditions. However, little of the He⁺ produced in the daytime is lost by recombination at night; it is suggested that the supply of He⁺ to the mid-latitude plasmasphere is, in effect, an escape process for neutral helium.     

Solutions to bi-Maxwellian transport equations for SAR-arc conditions

We have compared solutions obtained from the bi-Maxwellian based 16-moment transport equations with those obtained from the Maxwellian based 13-moment transport equations for conditions leading to the steady state, subsonic flow of a fully-ionized electron-proton plasma along geomagnetic field lines in the vicinity of the plasmapause. The bi-Maxwellian based equations can account for large temperature anisotropies and the flow of both parallel and perpendicular thermal energy, while the Maxwellian based equations account for small temperature anisotropies and only the total heat flow. Our comparison indicates that for Stable Auroral Red arc (SAR-arc) conditions leading to strong field-aligned heat flows (temperatures of 8000 K and temperature gradients of4K. km⁻¹ at 1500 km), the bi-Maxwellian based equations predict a different thermal structure in the topside ionosphere than the less rigorous Maxwellian based equations. In particular, the bi-Maxwellian based equations predict proton and electron temperature anisotropies with T > T, while the Maxwellian based equations predict the opposite behavior for the same boundary conditions. This difference is related to the way in which the temperature anisotropies and heat flows are treated in the two formulations. For the bi-Maxwellian based equations, the inclusion of separate heat flows for parallel and perpendicular thermal energy allows for the development of a pronounced tail in both the electron and proton distribution functions, which leads to temperature anisotropies with T > T. For the Maxwellian based equations, on the other hand, the tail development is restricted because only the total heat flow is considered. Consequently, as the heat flows down, the presence of an increasing magnetic field acts to produce an anisotropy with T > T, and this process dominates tail formation for the Maxwellian based equations.     

Rotational discontinuities in an anisotropic plasma

A general theory of rotational discontinuities is developed and the changes in the components of the plasma pressure, p_| and p, and in the magnetic induction, B, are found. For a given value of λ=(p_| − p) 4πμ/B² upstream only a limited range of downstream anisotropies are possible. If λ>0.6 upstream then isotropy is not possible downstream. Some special solutions are analysed and the identification of rotational discontinuities is the solar wind is discussed.     

A hybrid simulation study of magnetic reconnection in anisotropic plasmas

The process of magnetic reconnection in anisotropic plasmas is studied numerically using a 2-dimensional, 3-component hybrid simulation. The results of the calculation show that, when the plasma pressure in the direction perpendicular to magnetic field is larger than that in the parallel direction (e.g. P/P = 1.5), instability may greatly increase, speeding up the rate of reconnection. When P is smaller than P, (e.g., when P/P = 0.6), fire hose instability appears, which will restrain the tearing mode instability and the process of magnetic reconnection.     

Properties of the infrared dark cloud G79.2+0.38

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 X_13/18 between ¹³CO and C¹⁸O with the column density.     

Helium escape from the Earth''s atmosphere: The charge exchange mechanism revisited

We have studied the escape of neutral helium from the terrestrial atmosphere through exothermic charge exchange reactions between He⁺ ions and the major atmospheric constituents N₂, O₂, and O. Elastic collisions with the neutral background particles were treated quantitatively using a recently developed kinetic theory approach. An interhemispheric plasma transport model was employed to provide a global distribution of He⁺ ions as a function of altitude, latitude and local solar time and for different levels of solar ionization. Combining these ion densities with neutral densities from an MSIS model and best estimates for the reaction rate coefficients of the charge exchange reactions, we computed the global distribution of the neutral He escape flux. The escape rates show large diurnal and latitudinal variations, while the global average does not vary by more than a factor of three over a solar cycle. We find that this escape mechanism is potentially important for the overall balance of helium in the Earth's atmosphere. However, more accurate values for the reaction rate coefficients of the charge exchange reactions are required to make a definitive assessment of its importance.     

Neutral and ion-exospheres in the solar wind with applications to mercury

A model of planetary neutral and ion-exospheres in the solar wind is formulated for weak or lunar like solar-wind interaction with a planet. The neutral exosphere model allows for density and temperature variations and for rotation at the exobase. The ion-exosphere is produced by ionization of the neutral exosphere in the solar wind and its density distribution is obtained by solving the continuity equation in the drift approximation. Applying to Mercury a surface temperature distribution inferred from infra-red data and a vanishing bound neutral flux at the base, He and He⁺ density distributions are found. When the He atmosphere of Mercury is due entirely to the surface bombardment by solar wind He⁺⁺, the resulting He⁺ density is found to vary from 1.5 × 10⁻¹ to 10⁻³ cm⁻³ over the range 1.5–5 planetocentric radii on the dayside. These densities are found to be detectable by typical solar-wind plasma instruments. The possible effects of cyclotron-resonant scattering by interplanetary magnetic field fluctuations are examined and shown to be negligible. An electromagnetic plasma instability, triggered by the birth of ions in the exosphere, is shown to be important for the thermalization of the energy mode transverse to the interplanetary magnetic field, allowing more ions to be detected by solar-wind ion probes.     

The H-alpha variations of Epsilon Aurigae from the second to the fourth contact

Epsilon Aurigae was observed in Mar., Aug., 1983 and Jan., Mar., 1984 with Reticon at coudé focus of the McDonald 2.7m and 2.1m telescopes. Fifty-six observations were taken over eight nights during 2nd to 4th contact.

The H shows noticeable variations in profile, radial velocity, and equivalent width of both absorption and emission components. A similar phenomenon was detected during the corresponding phase of the 1955 – 1957 eclipse.

A model is proposed, in which the primary is a FO supergiant surrounded by a thin ring (or disk) of radius R = 450R and rotating at velocity V_sini = 60 – 70 kms⁻¹. This is the major source of the H emission component. The secondary is a type B star surrounded by a very extended envelope (R = 1000 R) and its rotational speed is similar to that of the ring of the primary. The B star heats a portion of the envelope comparable in size with the primary with enough hydrogen atoms in the lowest excited states, which cause the absorption of the emission from the primary.     

Physical and dynamical properties of a low-mass star-forming region

Eleven low-mass cores are found in the Orion Molecular Cloud 2 from VLA observations of the line emission of NH₃ (1,1). They are perhaps clumps prior to gravitatonal collapse with average radius of 0.03 pc and mass of 3.5 M, distributed along the central axes of filaments in the NS direction. We find a velocity gradient of 5 km s⁻¹ pc⁻¹ in the declination direction within a 3′ region. Based on our NH₃(1,1) observations and compared with dust continuum emission at millimilion wavelength as well as in the infrared, we suggest that most of these dense cores are probably protosteller condensations, not yet containing stellar cores, but are self-gravitating systems in thermodynamical equilibrium.     

A prediction for three neutrino masses and mixings and similarity between quark and lepton mixings

If neutrinos have mass, we give reasons for a possible pattern of three (squaed) mass eigenvalues: m₁² (2.8−5.8) (eV)², m₂² 0.01 (eV)², m₃² (1.5−1) × 10⁻⁴ (eV)². The flavor states ν_μ and ν_e are mixtures of the eigenstates with m₂ and m₃ with a significant mixing, corresponding to an effective mixing angle of about 0.45. The ν_τ is nearly the state with m₁; the other two effective mixing angles are about an order of magnitude smaller than 0.45. There is a marked similarity to mixing in the quark sector.     

Comparison of high-energy galactic and atmospheric tau neutrino flux

We compare the tau neutrino flux arising from the galaxy and the earth atmosphere for 10³E/GeV10¹¹. The intrinsic and oscillated tau neutrino fluxes from both sources are calculated. The intrinsic galactic ν_τ flux (E10³ GeV) is calculated by considering the interactions of high-energy cosmic-rays with the matter present in our galaxy, whereas the oscillated galactic ν_τ flux is coming from the oscillation of the galactic ν_μ flux. For the intrinsic atmospheric ν_τ flux, we extend the validity of a previous calculation from E10⁶ GeV up to E10¹¹ GeV. The oscillated atmospheric ν_τ flux is, on the other hand, rather suppressed. We find that, for 10³E/GeV5×10⁷, the oscillated ν_τ flux along the galactic plane dominates over the maximal intrinsic atmospheric ν_τ flux, i.e., the flux along the horizontal direction. We also briefly mention the presently envisaged prospects for observing these high-energy tau neutrinos.     

A kinematic study of the Galaxy

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 V_lsr = 273.9 km/s, obviously much higher than the IAU published value of 220 km/s. We have investigated the cause for this difference.     

Galactic cosmic-ray anisotropy and its heliospheric modulation, inferred from the sidereal semidiurnal variations observed in the rigidity range 300–600 GV with multidirectional muon telescope at Sakashita underground station

The existence of sidereal semidiurnal variation of cosmic-ray intensity in a rigidity region 10²-10³ GV has been reported by many researchers, but there is no consensus of opinion on its origin. In this paper, using the observed semidiurnal variations in a rigidity range (300–600 GV) with 10 directional muon telescopes at Sakashita underground station (geog. lat. = 36°, long. = 138°E, DEPTH = 80 m.w.e.), the authors determine the magnitudes (η₁, η₂) and directions (a₁, a₂) of the first- and second-order anisotropies in the following galactic cosmic-ray intensity distribution (j)

jdp = j₀{1 + η₁P₁(cos χ₁) + η₂P₂(cos χ₂)}dp

, where P_nis the nth order spherical function and χ_n is the pitch angle of cosmic rays with respect to a_n. For the determination, the influence of cosmic-ray's heliomagnetospheric modulation, geomagnetic deflection and nuclear interaction with the terrestrial material and also of the geometric configuration of the telescopes are taken into account. Usually, the semidiurnal variation is produced by the second-order anisotropy. The present observation, however, requires also the first-order anisotropy which usually produces only the diurnal variation, but can produce also the semidiurnal variation as a result of the heliospheric modulation. The first- and second-order anisotropies are characterized with η₁) > 0 and η₂ < 0 have almost the same direction (a₁ a₂) specified by the right ascension ( 0.75 h) and declination (δ 50°S) and, therefore, they can be expressed, as a whole, by an axis-symmetric anisotropy of loss-cone type (i.e. deficit intensities in a cone). It is noteworthy that this anisotropy approximately coincides with that inferred from the air shower observation at Mt Norikura in the rigidity region 10⁴ GV.     

A possible gas for solar neutrino spectroscopy

We discuss the possibility of using pure CF₄ to fill a 2000 m³ Time Projection Chamber in order to detect the solar neutrinos through the elastic scattering v_ee⁻ → v_ee⁻, with the threshold of 100 keV on the kinetic energy of the recoiling electron. In a volume of 2000 m³ of CF₄ at normal pressure and room temperature, which corresponds to a mass of 7.4 ton, we expect ~ 3300 of such events per year. The detector can give the spectrum of the low energy neutrinos from the Sun and it can identify solar neutrinos of different origin: pp, ⁷Be, and, eventually, ⁸B. We find that ¹⁴C is a possible severe source of background: it is necessary to have a ratio ¹⁴C/¹²C lower than 10⁻¹⁹ in order to be able to identify the pp neutrinos.