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NASA NTRS1974

Apollo scientific experiments data handbook

A brief description of each of the Apollo scientific experiments was described, together with its operational history, the data content and formats, and the availability of the data. The lunar surface experiments described are the passive seismic, active seismic, lunar surface magnetometer, solar wind spectrometer, suprathermal ion detector, heat flow, charged particle, cold cathode gage, lunar geology, laser ranging retroreflector, cosmic ray detector, lunar portable magnetometer, traverse gravimeter, soil mechanics, far UV camera (lunar surface), lunar ejecta and meteorites, surface electrical properties, lunar atmospheric composition, lunar surface gravimeter, lunar seismic profiling, neutron flux, and dust detector. The orbital experiments described are the gamma-ray spectrometer, X-ray fluorescence, alpha-particle spectrometer, S-band transponder, mass spectrometer, far UV spectrometer, bistatic radar, IR scanning radiometer, particle shadows, magnetometer, lunar sounder, and laser altimeter. A brief listing of the mapping products available and information on the sample program were also included.

Eichelman, W. F.↗
NASA NTRS1976

X-ray emission from high temperature plasmas

The physical processes occurring in plasma focus devices were studied. These devices produce dense high temperature plasmas, which emit X rays of hundreds of KeV energy and one to ten billion neutrons per pulse. The processes in the devices seem related to solar flare phenomena, and would also be of interest for controlled thermonuclear fusion applications. The high intensity, short duration bursts of X rays and neutrons could also possibly be used for pumping nuclear lasers.

Harries, W. L.↗
NASA NTRS1978

Gamma ray spectroscopy in astrophysics

Experimental and theoretical aspects of gamma ray spectroscopy in high energy astrophysics are discussed. Line spectra from solar, stellar, planetary, and cosmic gamma rays are examined as well as HEAO investigations, the prospects of a gamma ray observatory, and follow-on X-ray experiments in space.

Cline, T. L.↗
NASA NTRS1978

Imaging of X-ray aurorae from Spacelab

The Atmospheric X-ray Emission Telescope (AXET) is designed to image and measure the spatial, temporal, and spectral distributions of X-ray aurorae produced in the upper atmosphere by precipitating energetic electrons. The bremsstrahlung-produced X radiation penetrates to stratospheric depths where it can modify ozone, conductivity, and other critical atmospheric parameters. Remote sensing of this radiation from topside will provide vital data on solar-terrestrial relationships and mechanisms that could help trigger tropospheric response to solar activity. The X rays also provide direct information concerning the dynamics of radiation-belt processes within the magnetosphere. AXET is designed to detect sources up to 50 keV and to image them below 25 keV by means of directionally sensitive proportional counters with passive collimators. It will be mounted in the Space Shuttle on a single fixed platform designed to optimize viewing conditions for the anticipated orbits and aspects of early Spacelab missions.

Goldberg, R. A.↗
NASA NTRS1978

A phenomenological model of solar flares

The energy of solar flares is derived from the magnetic energy of fields convected to the sun's surface and subsequently converted to heat and energetic particles within the chromosphere. The circumstances of this conversion in most current models is magnetic flux annihilation at a neutral sheet. An analysis is conducted of the constraints of flux annihilation. It is shown that the present evidence of solar cosmic rays, X-rays, gamma-rays, and total energy suggests a choice of annihilation not at a neutral point, but by an enhanced dissipation of a field-aligned current. The field configuration is related both to its origin and to the extensive theory and laboratory experiments concerned with this configuration in magnetic fusion. The magnetic field model is applied to the August 4 flare. It is shown how the plasma heating in the annihilation region balanced by thermal conduction leads to a plasma temperature of about 20 million deg K.

Colgate, S. A.↗
NASA NTRS1980

HEAO 1 observations of gamma-ray lines from a solar flare

HEAO 1 observed gamma radiation, including the 2.223 MeV line of deuterium and the 4.43 MeV line of C-12, from a white-light solar flare of 1978 July 11. Line strengths over a 4 minute integration were 1.00 + or - 0.29 and 0.18 + or - 0.07 photons/sq cm s, respectively, and the continuum in the 1-5 MeV range fitted a spectrum 10 E to the -3rd photons/sq cm s keV. The 2.2 MeV line lagged 94 + or - 30 s behind the gamma-ray continuum, which itself was delayed about 20 s from the hard X-ray (not less than 40 keV) and microwave fluxes. This is the second flare for which both MeV-range lines and continuum have been observed, and the first for which simultaneous white-light observations exist. The prompt gamma-ray line (4.43 MeV) can be directly interpreted as an energy deposition of not greater than 7 x 10 to the 26th ergs per sec by energetic protons at photospheric depths. This is insufficient to maintain the white-light continuum by normal photospheric emission mechanisms.

Hudson, H. S.↗
NASA NTRS1980

Nonlinear calculation of a radial mode of oscillation of a hot white dwarf

A linearly unstable first harmonic radial mode of oscillation (period 0.86 s) of a hot white dwarf with a hydrogen envelope is analyzed in the nonlinear regime by application of the Stellingwerf technique to a nonlinear hydrocode. The mass and equilibrium luminosity of the hot white dwarf are 1.3 solar masses, and 1.6 x 10 to the 37th erg/s, respectively. A stable nonlinear mode is found to exist, in which appreciable shock damping occurs at and near the surface - the shock damping being the dominant stabilizing effect. This enhances the possibility that such an object can produce a pulsating X-ray source.

Degregoria, A. J.↗
NASA NTRS1980

Observation of the core of the Perseus cluster with the Einstein solid state spectrometer: Cooling gas and elemental abundances

Solid State Spectrometer observations of the core of the Perseus cluster have resulted in the detection of X-ray emission lines due to Si, S, and Fe. Analysis of the spectrum indicates that the X-ray emission has at least two characteristic temperatures. This is interpreted in the framework of radiative accretion in the core of the cluster. The derived parameters are a cooling time tc less than 2 x 109 yrs for the low temperature gas, a mass accretion rate of approximately 300 Mo/yr and a characteristic size of 10 to 20 Kpc for the cool gas. The Fe abundance in the core, approximately 0.4, is similar to the Fe abundance averaged over the whole cluster indicating that Fe emission is not strongly concentrated about NGC 1275. The Si and S abundances are consistent with solar values.

Mushotzky, R. F.↗
NASA NTRS1981

The Pinhole/Occulter Facility

A large occulting system in space can be used for high resolution X-ray observations and for large aperture coronagraphic observations in visible and UV light. The X-ray observations can combine high angular resolution in hand (10 keV) X-radiation with the high sensitivity of a multiple pinhole camera, and can permit sensitive observations of bremsstrahlung from nonthermal particles in the corona. The large aperture coronagraphs have two major advantages: high angular resolution and good photon collection. This will permit observations of small scale structures in the corona for the first time and will give sufficient counting rates above the coronal background rates for sensitive diagnostic analysis of intensities and line profiles for coronal structures in the solar wind acceleration region. The technical basis for performing observations with a large occulting system in these three wavelength ranges is described as well as a pinhole/occulter facility presently being considered for Spacelab. Some indications about future developments are included.

Hudson, H. S.↗
NASA NTRS1981

Observation of the core of the Perseus cluster with the Einstein solid state spectrometer - Cooling gas and elemental abundances

Solid State Spectrometer observations of the core of the Perseus cluster have resulted in the detection of X-ray emission lines due to Si, S, and Fe. Analysis of the spectrum indicates that the X-ray emission has at least two characteristic temperatures. This is interpreted in the framework of radiative accretion in the core of the cluster. The derived parameters are a cooling time less than or approximately equal to 2 x 10 to the ninth years for the low-temperature gas, a mass accretion rate of approximately 300 solar masses per year, and a characteristic size of 10-20 kpc for the cool gas. The Fe abundance in the core (approximately 0.4) is similar to the Fe abundance averaged over the whole cluster, indicating that Fe emission is not strongly concentrated about NGC 1275. The Si and S abundances are consistent with solar values.

Mushotzky, R. F.↗
NASA NTRS1982

Einstein detection of X-rays from the Alpha Centauri system

Detection of quiescent X-ray emission from the stellar components of the Alpha Cen system: Alpha Cen A (G2 V) and Alpha Cen B (K1 V) is reported. Contrary to previous theoretical expectations, both stars are found to be X-ray emitters and at about the same level: L sub x = 1.2 x 10 to the 27th and 2.8 x 10 to the 27th ergs/s for A and B, respectively; the sum of these values is in agreement with the emission level previously reported for Alpha Cen by Nugent and Garmire (1978). Comparison with previous chromospheric and transition region measurements suggests that Alpha Cen A and B may have changed in relative strength in recent years. The coronal temperature of the combined Cen AB source, which is dominated (approximately 2/3 of the total) by the K star is (2.1 + or - 0.4) x 10 to the 6th K, similar to that of the average solar corona; it is noted that this value is not consistent with the estimate of 5 x 10 to the 5th K quoted by Nugent and Garmire.

Golub, L.↗
NASA NTRS1982

Cygnus X-3 observed at photon energies above 500 GeV

High-energy gamma rays from Cyg X-3 have been observed with the twin 11-m mirrors of NASA JPL's solar energy facility, using the atmospheric Cerenkov technique, resulting in data from about 100,000 air shower events with an approximate threshold energy of 500 GeV for the August 29 to September 6, 1981 period. A positive signal whose amplitude is 10.9 + or - 2.5% of the background cosmic ray rate appears near phase 0.6 of the 4.8-hour cycle, where phase 0.0 corresponds to minimum X-ray emission. This, together with previous Cerenkov detections, indicates that the high energy emission from Cyg X-3 is evolving on a time scale of a few years and suggests that the present form of the system has a recent origin.

Lamb, R. C.↗
NASA NTRS1982

Discovery of 69 ms periodic X-ray pulsations in A0538-66

The detection of X ray pulsations with a period of 69.2126 ms from A0538-66 was done from the Einstein Observatory. A point source was located by the High Resolution Imager and a proportional counter registered a flux of 40 counts/sec over background. A column spectral density of 2 x 10 to the 23/sq cm identified the object as A0538-66. A persistent periodicity of 0.0692126 sec was observed throughout the event. The outbursts were not detected on three other observations of A0538-66, and a best fit to a change of rotation velocity indicated that the period observed was from a binary star with a Doppler shifted signal. The two stars are separated by less than 39 solar radii, with the larger star having a 40 solar radius. Consideration is given to the possibility that the X rays are due to accretion on a neutron star and that the two stars at times share a common envelope.

Skinner, G. K.↗
NASA NTRS1982

Gamma-ray and optical observations of the 1979 November 8 solar flare

The solar flare on 1979 November 8 11h 21m 28s UT was observed by the Tel Aviv telescope of the Big Bear Solar Observatory and the High Resolution Gamma-Ray Spectrometer on the High Energy Astronomy Observatory HEAO 3. Photographs in alpha hydrogen show the development of the flare and a subsequent Moreton wave. Although the flare was not detected with the high spectral resolution germanium detectors, the HEAO C-1 CsI shield detected a statistically significant signal above 80 keV, from 420 to 585 keV, and above 3.8 MeV. The temporal structure of microwave, optical, X-ray, and gamma-ray emission is consistent to within about 1 s with a simultaneous flare response at all energies. There is no evidence for either second-stage acceleration of charged particles (Bai and Ramaty, 1979) or a delay between gamma-ray and X-ray continuum emission due to energy-dependent electron energy loss times (Bai and Ramaty).

Riegler, G. R.↗
NASA NTRS1981

Photon-counting array detectors for space and ground-based studies at ultraviolet and vacuum ultraviolet /VUV/ wavelengths

The Multi-Anode Microchannel Arrays (MAMAs) are a family of photoelectric photon-counting array detectors, with formats as large as (256 x 1024)-pixels that can be operated in a windowless configuration at vacuum ultraviolet (VUV) and soft X-ray wavelengths or in a sealed configuration at ultraviolet and visible wavelengths. This paper describes the construction and modes of operation of (1 x 1024)-pixel and (24 x 1024)-pixel MAMA detector systems that are being built and qualified for use in sounding-rocket spectrometers for solar and stellar observations at wavelengths below 1300 A. The performance characteristics of the MAMA detectors at ultraviolet and VUV wavelengths are also described.

Timothy, J. G.↗
NASA NTRS1982

Simultaneous optical and X-ray bursts from 4U/MXB 1636-53

Methods of obtaining information about the geometry of X-ray burster systems from simultaneous optical and X-ray observations are discussed, and such simultaneous observations of 4U/MXB 1636-53 are reported. The physical idea of an optical burst being due to reprocessing of an X-ray burst in material in the vicinity of the compact object is discussed. The resulting modification of the X-ray burst signal is described in terms of an optical response function. Delay and smearing due to radiative processes are discussed along with those due to the geometry. For 4U/MXB 1636-53, the estimated delay is 2.5 seconds, the smearing is less than four seconds, and the maximum temperature of the reprocessing region is about 75,000 K. The projected area of the reprocessing region is about 6 x 10 to the 21st square cm. The neutron star is about 1.4 solar masses, the radius of the accretion disk is greater than 1.5 lt-sec, and the mass of the Roche lobe filling companion star is less than 2.0 solar masses, corresponding to a binary period between about one and ten hours.

Pedersen, H.↗