The λ 747 coronal line at the 1966 eclipse

Observations are presented of emission line resonance polarization in Fe xiii 10747 at the total solar eclipse of 12 November 1966. Useful data, with angular resolution 15, describe three quadrants of the corona from 1.08 R to a maximum of 1.6 R . The direction of the electric vector of observed polarization is perpendicular to the solar limb, to the limits of accuracy of measurement, in at least 74% of all cases. Departures in the other points are consistent with the magnetic depolarization expected from the non-radial fields of streamers. Polarizations observed range from near zero at the limb to 80 % and higher at 1.6 R . Averaged polarization is highest in non-streamer regions, where above 1.2 R it suggests pure radiative excitation of the 10747 line. Below 1.2 R , and in a dense streamer, the polarization is significantly depressed, indicating dominant collisional excitation of the line wherever the electron density exceeds 50 × 10⁶ cm^–3.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

The interaction of matter and radiation in the hot model of the Universe,II

Heating of the primaeval plasma prior to the epoch of recombination results in distortions in the Rayleigh-Jeans region of the microwave relic radiation spectrum (1–60 cm, or more exactly =2.5_–7/8 cm). The present observational data allow limits to be set to such energy injection from which follow upper limits to (a) the amount of antimatter in the universe; (b) the parameters of primaeval turbulence; and (c) the adiabatic fluctuation spectrum for small masses (M<10¹¹ M ).If the heating takes place prior to the epocht=10_1012/5 sec (and in particular at the annihilation of electron-positron pairs atT10⁸–10¹⁰ K,t<300 sec), no observable distortions are expected in the relic radiation spectrum. Here =/_crit is the dimensionless average density of matter in the universe.Translated from the Russian by D. F. Smith.     

An Apparent Gap in Stellar Mass Distributions at ≈ 0.7 M⊙ and a Possible Explanation

Mass functions for samples of white dwarf stars and for a largeheterogeneous sample of nearby stars appear to have unexplained deficitsin the 0.70 M to 0.75 M range. The existence, ornon-existence, of this anomaly constitutes a definitive test of afractal cosmological model that inherently predicts a gap in stellarmass functions at 0.73 M .     

Apparent radii and other parameters for 416 B5 V-F5 V stars of the catalogue of the geneva observatory

Apparent radius, visual brightness, effective temperature and absolute radius for 416 B5 v-F5 v stars of the catalogue of the Geneva Observatory (Rufener, 1976) have been determined.Twenty-eight stars, anomalous in log versus (m _v)₀ diagrams, have been singled out. A good correlation for seven stars, in common with the list of Hanbury Brownet al. (1974), has been found. Similar parameters determined for 279 B5 v-F5 v stars of two preceding papers (Fracassiniet al., 1973, 1975) have allowed us to determine the averaged diagrams logq _v/q, logR/R and logT _e versus (B-V)₀ for 695 B5 v-F5 v stars.Moreover, in the present paper a good correlation logq _v/q versus logR/R and careful relation M _v=–7.40logR/R +3.31 for B5 v-F5 v stars have been determined. Plain correlations between logR/R and blanketing parameterm ₂ for some spectral types seem to point out that there arereal differences in the absolute radii of stars of thesame spectral type, in agreement with recent researches on the HR diagram (Houck and Fesen, 1978).Systematic differences between double (spectroscopic and visual) and single stars are found. In particular, the averaged relation m ₂ versus logR/R shows that A2 v-F5 v double stars may have a higher metallicity indexm ₂ and smaller absolute radii than single stars. Finally, the diagram logv sini versus logR/R confirms some properties of binary systems found by other researchers (Huang, 1966; Plavec, 1970; Levato, 1974; Kitamura and Kondo, 1978).Thesis for the degree in Applied Physics.     

Evolution of massive close binaries and formation of neutron stars and black holes

Main results of computations of evolution for massive close binaries (10M +9.4M , 16M +15M , 32M +30M , 64M +60M ) up to oxygen exhaustion in the core are described. Mass exchange starting in core hydrogen, shell hydrogen and core helium burning stages was studied. Computations were performed assuming both the Ledoux and Schwarzschild stability criteria for semiconvection. The influence of UFI-neutrino emission on evolution of close binaries was investigated. The results obtained allow to outline the following evolutionary chain: two detached Main-Sequence stars — mass exchange — Wolf-Rayet star or blue supergiant plus main sequence star — explosion of the initially more massive star appearing as a supernova event — collapsed or neutron star plus Main-Sequence star, that may be observed as a runaway star — mass exchange leading to X-rays emission — collapsed or neutron star plus WR-star or blue supergiant — second explosion of supernova that preferentially disrupts the system and gives birth to two single high spatial velocity pulsars.Numerical estimates concerning the number and properties of WR-stars, pulsars and X-ray sources are presented. The results are in favour of the existence of UFI-neutrino and of the Ledoux criterion for describing semiconvection. Properties of several well-known X-ray sources and the binary pulsar are discussed on base of evolutionary chain of close binaries.     

Structure of close binaries

Internal models have been obtained for uniformly rotating synchronous close binary systems using a modified double approximation scheme. We have considered primaries of 10M , 5M , and 2M with mass ratios of 0.0 to 1.0 in steps of 0.1, and some results are given for a 1M primary with a mass ratio of 1.0. A maximum luminosity reduction of 2.3% was found for a 10M primary with a mass ratio of 1.0 and 7.7% for a mass ratio of 0.0. The corresponding values for 5M are 2.0% and 7.0%, and for 2M they are 1.6% and 5.3%, respectively. These values were not found to be sensitive to small changes in composition. The maximum equatorial velocity varies from 399 km s^–1 for 2M to 567 km s^–1 for 10M when the mass ratio is zero, but these velocities decrease by 200–300 km s^–1 if the mass ratio is unity. The effect of gravity darkening on the apparent position of the primary in the theoretical H-R diagram was investigated. It was determined that an unresolved close binary of unit mass ratio can lie up to 0.9 magnitudes (depending on inclination) above the main sequence, whereas if the effects of distortion are ignored this number is at most 0.75 magnitudes. There seems to be some observational support for the larger value. Two models of the secondaries are given and their dimensions are compared with their critical Roche lobes.     

The product of the globular cluster collapse

In this paper we calculate the number of close binaries formed during the evolution process of a globular cluster core. The globular cluster core is assumed to contain a massive black hole at its center. We show that the central black hole can drive binaries formation in the core and the rate of binaries formation depends on the mass of the black hole at its center. When the massM of the black hole is between 10² M and 3×10³ M , there will be a few binaries formed. When the mass of the black hole is 4×10³ M M6×10³ M , the number of binary star formation will suddenly increase with a jump to the maximum value 58. When the mass of the black hole is 7×10³ M M9×10³ M , the number of binary star will immediately decrease. Whether cluster X-ray is produced mainly by the central black hole or by binaries in the core depends on the mass of the central black hole. Therefore, two cases arise: namely, black hole accretion domination and binaries radiation domination. We do think that we cannot exclude the possibility of the existence of a central black hole even when binary radiation characteristics have been observed in globular cluster X-ray sources.     

Nature of the symbiotic binary V 1329 Cyg

The published photometric and spectroscopic data of the symbiotic binary V 1329 Cyg are interpreted. It is shown, that V 1329 Cyg is an eclipsing binary with an elliptical orbit orbit (e=0.28). The cooler component fills up the Roche-lobe at periastron. A model of moving gaseous structures in the system is proposed and their influence on the radial velocity curve is shown. The following characteristics of the system are derived: the cooler component is an M6 giant with mass 7.9M , radius 339R and luminosityM _bol=–5.42, the hot component is a white dwarf surrounded by an accretion disk. The mean distance between the components is 842R and in periastron it decreases to 605R .     

Hidden mass in the solar neighborhood

It is suggested that the minimum mass of a star at the time of its formation is approximately 0.01M . Making use of this fact and the stellar mass functionF(M) M ^–, it is found that the hidden mass (or the missing mass) in the solar neighborhood may be explained by the presence of a large number of invisible stars of very low mass (0.01M M<0.07M ).     

Observations of stray-light and sunspot intensities during the Mercury transit of 1970 May 9

In order to test the usual method for correcting sunspot intensity measurements for stray light, we have measured, during the Mercury transit of 1970 May 9, the intensities of Mercury, a sunspot umbra, and the aureole. The direct observations result in Mercury intensities < 0.06 I and aureole intensities <0.01 I . The stray light correction to the spot intensities has been <(0.03 ± 0.01) I . The main contribution to the stray light on the solar disc is shown to be produced by a spread-function with a half width of 10 arc sec. Consequently, for stray light corrections the range R R + + 20 in the aureole has to be measured very precisely; furthermore, a remarkable fraction of the stray light in the center of an umbra originates from the surrounding penumbra.Mitteilungen aus dem Fraunhofer Institut, Nr. 102.     

Temperature gradients in the inner corona

Emission gradient curves for extreme ultraviolet (EUV) resonance lines of O vi and Mg x have been constructed from spectroheliograms of quiet limb regions observed with the Harvard experiment on Skylab. An analysis of these data suggests that the coronal temperature rises throughout the height range 1.03R r1.3R . This result implies that in quiet regions there is significant coronal heating beyond r = 1.3R .Now at E.O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, D.C., U.S.A.     

Solar brightness distribution at 8.6 mm from interferometer observations

The radial brightness distribution of the quiet Sun at 8.6 mm is synthesized from observations using a sixteen element east-west interferometer in Nagoya. The observed brightness is flat from the disk center to 0.8R . A slight darkening appeared between 0.8R and the limb. No evidence of the bright ring near the limb is found. The radio radius at 8.6 mm is 1.015±0.005R . In addition there exists a coronal component just outside the radio limb.     

Supernova models with slow energy pumping and galactic supernova remnants

The study of supernova (SN) models with slow energy pumping is continued. At maximum luminosity the main characteristics of a SN are shown to be independent of the initial structure of the model (Table I, Figure 1). However, they depend on the massM _e of the envelope, and on the intensity of energy pumpingL , with an increase ofM _e leading qualitatively to the same changes in the SN parameters as a decrease inL (Table I, Figures 2 and 3). A simple relationship connecting the important SN parameters is obtained (Equation (6)). From the inflection of the color indexB-V curve, the possibility of deriving the characteristic time of energy pumping with intensityL 10⁴⁴ erg s^–1 is pointed out. The comparison of the extragalactic type I SN observations with the results of calculations leads to the estimate ofM _e 0.3–0.7M.An investigation of the galactic type I SN remnants is carried out (Table III). The estimate ofM _e 0.2–0.3M is obtained for the remnants of supernovae SN 1006, SN 1572, and SN 1604. It completely fits the results for the extragalactic type I SNs. The total initial mass of SN 1604 presupernova was shown to be at least about 7M .It was established that the Crab nebula resulted from the outburst of a peculiar SN. The unique properties of such SNs, including SN 1054, are due to the low intensity of energy pumping (L 10⁴² erg s^–1). The mass of the envelope of the Crab nebula is evaluated to beM _e 0.7M . SN 1054 was shown to have m _max ^v =–4 _m ^. 0 at maximum luminosity.     

Three-component fluid model of the universe of critical density

A three-component fluid model of the Universe during the recombination era is analysed for = _c ( _c is the critical density). In addition to the well-known instability of the Jeans mode at 10⁹ M , we find two more unstable modes at 10¹² M .     

Evolution of massive close binaries

The evolution of a binary system with components of 10M and 8M is computed through a case B of mass exchange. It is found that after the end of core helium burning, a second stage of mass transfer from the primary occurs. Carbon ignition is prohibited by the large neutrino losses in the degenerated core. The primary remnant, a 1.12M star, ends as a white dwarf. A comparison with the 10M single evolution is made.This research is supported by the National Foundation of Collective Fundamental Research of Belgium (F.K.F.O.) under No. 10303.     

Mass accretion onto massive white dwarfs

We have studied the thermonuclear runaways which develop on white dwarfs of 1.205M and 1.358M accreting hydrogen rich material at 10^–10 M yr^–1. It is found that ignition of this material occurs at densities in excess of about 10⁴ gm cm^–3 and that the critical accumulated mass required to initiate the runaway is 0.7(1.5)×10^–4 M for a 1.358(1.205)M white dwarf.     

Quasi-stationary solar wind in ray structures of the streamer belt

It is shown on the basis of analyzing the LASCO/SOHO data that the main quasi-stationary solar wind (SW), with a typical lifetime of up to 10 days, flows in the rays of the streamer belt. Depending on R, its velocity increases gradually from V3 km s^–1 at R1.3 R to V170 km s^–1 at R15 R . We have detected and investigated the movement of the leading edge of the main solar wind at the stage when it occupied the ray, i.e., at the formative stage of a quasi-stationary plasma flow in the ray. It is shown that the width of the leading edge of the main SW increases almost linearly with its distance from the Sun. It is further shown that the initial velocity of the inhomogeneities (`blobs') that travel in the streamer belt rays increases with the distance from the Sun at which they originate, and is approximately equal to the velocity of the main solar wind which carries them away. The characteristic width of the leading edge of the `blob' R , and remains almost unchanging as it moves away from the Sun. Estimates indicate that the main SW in the brightest rays of the streamer belt to within distances at least of order R3 R represents a flow of collisional magnetized plasma along a radial magnetic field.     

The parameters of planetary nebulae and their central stars derived from observations

On the basis of data on planetary nebula (PN) central star temperatures obtained by measurements in the ultraviolet (UV) range, the empirical calibration dependence between the number of Lyman photons emitted by a central starS and PN diameterD, is constructed. The temperatures of 118 PN central stars are estimated with this dependence. It is shown that the central star masses are distributed in a wide interval from 0.5 to 1.2M . About 60% of all stars have masses <0.6M , about 25% have masses >0.6M and the remainder have masses 0.6M . The averaged empirical tracks of evolution of low-mass (<0.6M ) and massive (>0.6M ) central stars differing considerably from each other are constructed. It is shown that the majority of central stars may possess hot chromospheres (T>2×10⁵ K) which spread for several tens of radii of the central star. The PN originates as a result of ionization of the matter ejected by a red giant at the superwind stage. The cause for this ionization is the UV radiation of the PN central star.     

Polar coronal plumes

Polar coronal plumes are modeled using concentrations of magnetic flux at 1.01R , and assuming the field is current-free, or a potential field. Identifying the density enhancement of plumes with magnetic flux concentration produces good agreement between 1.01R and 1.10R , for model conditions of a large background magnetic field and a plume separation of 50 000 to 70 000 km at the base. Beyond 1.10R , both plumes and the potential field diverge very nearly as r ².Also Department of Astrogeophysics, University of Colorado, Boulder, Colo. 80309, U.S.A. Presently visiting Stanford University Institute for Plasma Research, Via Crespi, Stanford, Calif. 94303, U.S.A.     

Population synthesis in starburst galaxies: Mkn 710

Evolutionary population synthesis models have been built to study the properties of the starforming processes taking place in starburst regions. BothZ andZ /10 stellar evolutionary tracks have been used to take into account that starburst galaxies are generally metal deficient. A very small time step allows us to follow the evolution of the cluster even during very short phases. Three parameters have been synthesized: the ratio of the Siiv (1400 Å) andCiv (1550 Å) UV absorption lines, that characterize the predominant massive stars in the cluster, the ratio of the WR_bump over the H luminosity, tracer of WR stars and the FIR luminosity, directly related to the extinction due to dust in the cluster. The predictions have been compared with observations of the burst taking place in the galaxy Mkn 710. The burst age is 5–6 Myr. The stars seem to have formed simultaneously with a mass spectrum whose slope is in the range (1,2) for massive stars. The upper mass limit has to be 60M . We have performed a systematic study of a sample of 17 starburst galaxies searching for differences in the star formation process that may be related to different metallicities or morphological types.Based on observations with the International Ultraviolet Explorer collected at the Villafranca Satellite Tracking Station of the European Space Agency.