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NASA NTRS1973

After Apollo - Fission origin of the moon

The present work maintains that the Apollo moon data substantiate the fission theory of the origin of the moon. It has been objected to this theory that prior to fission, the total mass and angular momentum of the earth-moon system would have to be greater than the present total of the earth and the moon, which would imply that angular momentum must have been lost since the fission. The present work states that this loss of momentum can be accounted for by the subsequent boiling off of a large amount of the original lunar mass. This would also mean that the moon ought to be greatly impoverished in volatiles, which it, indeed, is according to Apollo data. It is suggested that at one time the solar system was a binary star, namely, the sun and Jupiter. Successive fissions of Jupiter would have created other planets, which themselves could undergo fission, producing satellites.

Okeefe, J. A.↗

NASA NTRS1974

Binary stellar winds

Stellar winds from a binary star will interact with each other along a contact discontinuity. We discuss qualitatively the geometry of the flow and field resulting from this interaction in the simplest case where the stars and winds are identical. We consider the shape of the critical surface (defined as the surface where the flow speed is equal to the sound speed) as a function of stellar separation and the role of shock waves in the flow field. The effect of stellar spin and magnetic sectors on the field configuration is given. The relative roles of mass loss and magnetic torque in the evolution of orbital parameters are discussed.

Siscoe, G. L.↗

NASA NTRS1975

The peculiar object HD 44179 /'The red rectangle'/

A strong infrared source detected in the AFCRL sky survey is confirmed, and is identified with the binary star HD 44179, embedded in a peculiar nebula. UBVRI and broad-band photometry between 2.2 and 27 microns are combined with blue, red, and near-infrared spectra, polarimetry and spectrophotometry of the star, and a range of direct and image-tube photographs of the nebula, to suggest a composite model of the system. In this model, the infrared radiation derives from thermal emission by dust grains contained in a disklike geometry about the central object, which appears to be of spectral type B9-A0 III and which may be in pre-main-sequence evolution. Two infrared emission features are found, peaking at 8.7 and 11.3 microns, the latter corresponding to the feature seen in the spectrum of the planetary nebula NGC 7027. The complex nebular structure is discussed on the basis of photographs through narrow-band continuum and emission-line filters. The polarization data support the suggestion of a disk containing some large particles. No radio continuum emission is detected.

Cohen, M.↗

NASA NTRS1975

Evidence for X-ray emission from Capella

X-ray emission in the range from 0.2 to 1.6 keV has been detected from an area of the sky which contains the binary star system Capella. The X-ray source is at most a few arc minutes in extent and shows no spectral turnover at low energy, consistent with a nearby source. We suggest Capella as the source of this emission and that this object belongs to a new class of galactic X-ray sources with a luminosity of 10 to the 31st to 10 to the 34th ergs per sec. Emission from this class of objects is variable, predominantly below 2 keV, and originates from nearby stellar objects.

Catura, R. C.↗

NASA NTRS1974

Binary stellar winds

Stellar winds from a binary star pair will interact with each other along a contact discontinuity. We discuss qualitatively the geometry of the flow and field resulting from this interaction in the simplest case where the stars and winds are identical. We consider the shape of the critical surface (defined as the surface where the flow speed is equal to the sound speed) as a function of stellar separation and the role of shock waves in the flow field. The effect of stellar spin and magnetic sectors on the field configuration is given. The relative roles of mass loss and magnetic torque in the evolution of orbital parameters is discussed.

Siscoe, G. L.↗

NASA NTRS1975

The HEAO A-2 experiment on the spatial and spectral structure of the X-ray sky /0.2-60 keV/

The HEAO A-2 experiment is described which is designed to observe the spectral and spatial structure of cosmic X-radiation over the entire sky with the minimum sensitivity and cross checks required to achieve a number of objectives. Developments in X-ray astronomy are discussed which are relevant to the experiment, including setting a lower limit on the number of discrete sources contributing to the background flux, determining the spatial dependence of the flux, observations of the spectral components of discrete sources, and the study of X-ray absorption by interstellar gas and the atmospheres of binary stars associated with pulsating X-ray sources. It is shown that systematics-free measurements will be made by making simultaneous observations of single sources with several detectors, by using two-layer detectors to eliminate the effects of electron contamination, and by incorporating magnets into low-energy detectors to minimize electron contamination.

Boldt, E.↗

NASA NTRS1975

Upper mass limits for stable rotating white dwarfs

Models of nonmagnetic axisymmetric differentially rotating zero-temperature white dwarfs are constructed and tested for stability. Upper mass limits, beyond which models become secularly and dynamically unstable to growth of nonaxisymmetric perturbations, are found at 2.5 solar masses and 4.6 solar masses, respectively. The upper mass limit for secular stability is practically the same for the two angular momentum distributions considered. Crude growth rates due to gravitational radiation and degenerate-electron viscosity are calculated for the secularly unstable models. Except for a narrow parameter range, gravitational radiation is the dominant destabilizing mechanism. For masses between 3.5 and 4.6 solar masses, the secular instability grows on a time scale of about 10 to 1000 years; for masses exceeding about 4.6 solar masses, the dynamic instability grows on a time scale of seconds. Implications of these results for mass-transfer binary star systems and degenerate stellar cores are discussed.

Durisen, R. H.↗

NASA NTRS1975

Eclipses by an elliptical torus

A general procedure for computing the effects of eclipses by a torus, including both the outer horizon and the inner or hole horizon, was developed. The procedure can be used for any of the simple figures of revolution encountered in binary-star models. That is, the thickness can be made negligible to produce a thin ring, the hole radius can be set to zero to yield a thin disk, the radius to the center of the elliptical meridian section can be brought to zero to give an ellipsoid of revolution, or the equatorial axis of the elliptical meridian section can be made to equal zero to produce a section of a right circular cylinder.

Wilson, R. E.↗

NASA NTRS1977

Recognition of compact astrophysical objects

NASA's Laboratory for High Energy Astrophysics and the Dept. of Physics and Astrophysics at the Univ. of Md. collaberated on a graduate level course with this title. This publication is an edited version of notes used as the course text. Topics include stellar evolution, pulsars, binary stars, X-ray signatures, gamma ray sources, and temporal analysis of X-ray data.

Ogelman, H.↗

NASA NTRS1977

Time scale for the formation of the earth and planets and its role in their geochemical evolution

The initial mass of the solar nebula is discussed. Models of a massive nebula (two solar masses and more) encounter serious difficulties: an effective mechanism of transfer of the momentum from the central part of the nebula outward, capable of leading to formation of the sun and removal of half the mass of the nebula from the solar system has not been found. As a consequence of the instability of these models, their evolution can end with the formation, not a planetary system, but of a binary star. The possibility is demonstrated of obtaining acceptable growth rates for Uranus and Neptune by prolonging the thickening of preplanetary dust in the region of large masses. The important role of large bodies in the process of formation of the planets is noted. The impacts of such bodies, moving in heliocentric orbits, could have imparted considerable additional energy to the forming Moon, which, together with the energy given off by the joining of a small number of large protomoons, could have led to a high initial temperature of the moon.

Safronov, V. S.↗

NASA NTRS1977

Cloud physics laboratory project science and applications working group

The conditions of the expansion chamber under zero gravity environment were simulated. The following three branches of fluid mechanics simulation under low gravity environment were accomplished: (1) oscillation of the water droplet which characterizes the nuclear oscillation in nuclear physics, bubble oscillation of two phase flow in chemical engineering, and water drop oscillation in meteorology; (2) rotation of the droplet which characterizes nuclear fission in nuclear physics, formation of binary stars and rotating stars in astrophysics, and breakup of the water droplet in meteorology; and (3) collision and coalescence of the water droplets which characterizes nuclear fusion in nuclear physics and processes of rain formation in meteorology.

Hung, R. J.↗

NASA NTRS1978

Spectroscopy of the extreme-ultraviolet source Feige 24 - The binary orbit and the mass of the white dwarf

Results are reported for coude spectroscopy of the extreme-ultraviolet white dwarf Feige 24. Radial velocities of the H-alpha, He I 5876-A, and He I 6678-A emission lines, and the underlying M-dwarf absorption features, were determined from spectrograms obtained with the Lick 3-m telescope. The velocities show a binary period of 4.239(+ or - 0.0015) days. The emission-line and absorption-line velocities agree in phase, which indicates that the emission lines originate in the atmosphere of the M-dwarf secondary as a result of reprocessing of the EUV radiation. This effect is modeled, and the observed amplitude of the emission-line variability is used to place a lower limit on the orbital inclination. From these and other data it is shown that the mass of the white dwarf lies between 0.46 and 1.24 solar masses. Some possible implications for the evolution of binary stars are briefly discussed.

Thorstensen, J. R.↗

NASA NTRS1978

A search for optical pulsations from GX 1+4 at H-alpha

H-alpha observations of the binary-star candidate for the slowly pulsating hard X-ray source GX 1+4 are reported which were undertaken to search for pulsations in the H-alpha flux that are synchronous with the X-ray period of about 2 min. No significant periodic variation of the candidate star was detected in the frequency band searched. Three-sigma upper limits of 1.7% (sinusoidal pulse shape) and 0.7% (X-ray pulse shape) are set for the pulsed fraction of the H-alpha flux. It is noted that because of possible diffusion from a cloud that is optically thick to Balmer radiation, the observed lack of pulsations in the H-alpha flux need not compromise the identification of GX 1+4 with the candidate star.

Krzeminski, W.↗

NASA NTRS1979

The optical counterpart of GX 339-4, a possible black hole X-ray source

Optical studies of the galactic X-ray source GX 339-4 (4U 1658-48), which led to its recent identification as reported by Doxsey et al. (1979), are presented. Reddening and distance estimates are given, as well as evidence for optical variability on differing time scales. The emission-line spectra and UBV photometry suggest that GX 339-4 may be at about 8 kpc and have a main-sequence B star binary companion. Both the optical spectrum and optical/X-ray luminosity ratio for GX 339-4 may be similar to Cir X-1.

Grindlay, J. E.↗

NASA NTRS1980

An Assessment of Ground-Based Techniques for Detecting Other Planetary Systems. Volume 2: Position papers

The capabilities of several astronomical interferomenter system concepts are assessed and the effects of the Earth's atmosphere on astrometric precision are examined in detail. Included is an examination of the use of small aperture interferometry to detect planets in binary star systems. It is estimated that, for differential astrometric observation, an amplitude interferometer having two separate telescopes should permit observations of stars as faint as 14th magnitude and a positional accuracy of 0.00005 arc-sec. Instrumental, atmospheric, and photon noise errors that apply to interferometric observation are examined. It is suggested that the effects of atmospheric turbulence may be eliminated with the use of two color refractometer systems. Several sites for future telescopes dedicated to the search for planetary systems are identified.

Black, D. C.↗

NASA NTRS1980

Ultraviolet spectroscopy of binary systems

Four typical binary systems that illustrate some of the major problems in the study of binary stars are discussed. Consideration is given to (1) high-luminosity X-ray sources typified by Cyg X-1 (HDE 226868) and Vela XR-1 (HD 77581), (2) low-luminosity X-ray sources (HZ Her), (3) late-type systems of W UMa and RS CVn type, and (4) cool supergiants with a hot companion (VV Cephei).

Dupree, A. K.↗

NASA NTRS1980

Design aspects of a laser gravitational wave detector in space

Certain optical and mechanical aspects of a proposed laser gravitational wave antenna in space are briefly discussed. The proposed concept consists of a free-mass antenna with the test masses separated by a distance of 1,000,000 km. A laser heterodyne technique is employed to measure the distance change between test masses resulting from gravitational wave interaction. The proposed scheme is considered to offer the necessary sensitivity to detect gravitational radiation from binary stars predicted by General Relativity Theory.

Decher, R.↗

NASA NTRS1981

The ultraviolet spectrum of the twin-degenerate interacting binary G61-29

A low-resolution IUE spectrum (1200 A-1900 A) of the twin-degenerate white-dwarf binary star G61-29 is presented. A comparison is made to similar IUE spectra of the old novae DQ Her and V603 Aql. G61-29 shows N V 1240 A and He II 1640 A in emission. Unlike the old novae, the C IV 1550 A doublet is not present. It is proposed that the mass-losing He white dwarf (with a mass of 0.02 solar mass) is the H-exhausted, He-rich core of an old star in which the original CNO nuclei have been converted to N-14 by the CNO-cycles.

Lambert, D. L.↗