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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1972

Coronal survey in X-rays of O VII and Ne IX.

Results of a rocket experiment flown on Apr. 29, 1971, in which a survey of the solar corona was carried out with a pair of collimated Bragg spectrometers to study the resonance, intersystem, and forbidden line emission from the helium-like ions O vii (22 A) and Ne ix (13 A). The observed X-ray emission came from the general corona, seven plage regions, and one dynamic feature - the late stage of a small flare. From the intensity of the O vii and Ne ix resonance lines the electron temperature and emission measure of the individual emitting regions are derived on the basis of two models, one in which the region is assumed to be isothermal and another in which the emission measure decreases exponentially with increasing temperature. The latter model, which is the most adequate of the two, yields for the electron temperature of the time-varying feature 2,000,000 to 3,000,000 K, for the other active regions 1,500,000 to 2,500,000 K, and for the general corona 1,300,000 to 1,700,000 K. The Ne ix emitting regions are about 1.5 times as hot as the O vii regions.

Acton, L. W.↗
NASA NTRS1971

Acceleration and propagation of high Z cosmic rays in a pulsar environment

The survival of high Z nuclei in the X-ray photon field of a pulsar is investigated. For heavy nuclei with energies greater than or equal to 100 GeV/nucleon, 100 keV X-ray photons have sufficient energy to cause photodisintegration with cross sections of approximately 10 to the minus 25th power sq cm. Using the observed properties of the Crab pulsar, extrapolation back to epochs when the pulsar was more active indicates that the photon field is sufficiently dense to prevent the acceleration of heavy nuclei within the velocity of light cylinder. On this model, the upper limit on the energy of the escaping nuclei varies with time. The models for cosmic ray acceleration in supernova explosions or by pulsars will be related to experimental observations.

Balasubrahmanyan, V. K.↗
NASA NTRS1972

X-ray emission from the galactic disk

A search was made of a diffuse component of X-rays 1.5 keV associated with an interarm region of the galaxy at galactic longitudes in the vicinity of 60 deg. A statistically significant excess associated with a narrow disk component was detected. The angular extent of this component has a most probable value of 2 deg and may be as large as 7 deg at 90% confidence. The best fit spectrum yields an intensity of 2.9 photons 1/(cm2-sec-ster) over the 2 to 10 keV range. The 3 sigma upper limit to any emission (e.g. iron line) in a 1.5 keV band centered at 7 keV from galactic latitudes h or = 3.5 deg is .3 photons 1/(cm2-sec-ster). Several possible emission models are discussed, with the most likely candidate being a population of unresolvable low luminosity discrete sources.

Bleach, R. D.↗
NASA NTRS2020

The Slow Demise of the Long-Lived Sn 2005ip

The Type IIn supernova (SN IIn) 2005ip is one of the most well-studied and long-lasting examples of an SN interacting with its circumstellar environment. The optical light curve plateaued at a nearly constant level for more than five years, suggesting ongoing shock interaction with an extended and clumpy circumstellar medium (CSM). Here, we present continued observations of the SN from ∼1000 to 5000 d post-explosion at all wavelengths, including X-ray, ultraviolet, near-infrared (NIR), and mid-infrared. The UV spectra probe the pre-explosion mass loss and show evidence for CNO processing. From the bolometric light curve, we find that the total radiated energy is in excess of 10 50 erg, the progenitor star’s pre-explosion mass-loss rate was >~ 1 × 10 −2 Mꙩ yr −1 , and the total mass lost shortly before explosion was >~1Mꙩ, though the mass lost could have been considerably larger depending on the efficiency for the conversion of kinetic energy to radiation. The ultraviolet through NIR spectrum is characterized by two high-density components, one with narrow high-ionization lines, and one with broader low-ionization H I, He I, [OI], Mg II, and Fe II lines. The rich Fe II spectrum is strongly affected by Lyα fluorescence, consistent with spectral modelling. Both the Balmer and He I lines indicate a decreasing CSM density during the late interaction period. We find similarities to SN 1988Z, which shows a comparable change in spectrum at around the same time during its very slow decline. These results suggest that, at long last, the shock interaction in SN 2005ip may finally be on the decline.

stars↗
NASA NTRS1971

X-ray observation of a new soft source in Cygnus.

The location of the new X-ray source, designated Cygnus X-6, is discussed. The polycarbonate window counter detected Cyg X-6 only in the pulse-height interval from 0.5 to 1.3 keV. A total of 44 counts was acquired from the source above a diffuse X-ray and non-X-ray background of 18 plus or minus 3 counts. The polycarbonate pulse-height spectrum for Cyg X-6 is presented together with the calculated counter response to three different model source spectra.

Coleman, P. L.↗
NASA NTRS1972

Extragalactic cosmic rays.

A detailed analysis is given of the possibility that a large part of the primary cosmic-ray flux is of extragalactic origin. The problems encountered in theories of galactic cosmic rays are first critically discussed. The objections that have previously been raised to extragalactic theories, particularly on energetic grounds, are then examined. The general problem of the propagation of cosmic rays which are ejected from galactic nuclei or in galactic winds to fill clusters and superclusters is dealt with next. Attention is also given to the limits which are set on the presence of extragalactic cosmic rays by observations of high-energy electrons and background X-rays and gamma rays, or the heating of a hypothetical intergalactic gas. Observable effects of cosmic rays between galaxies are studied, and the possible sources of the local cosmic-ray protons in the extragalactic model are considered.

Brecher, K.↗
NASA NTRS1972

X-ray emission from the galactic disk.

A search was made for a diffuse component of greater than 1.5 keV X rays associated with an interarm region of the Galaxy at galactic longitudes in the vicinity of 60 degrees. A statistically significant excess associated with a narrow disk component was detected. The angular extent of this component has a most probable value of 2 degrees. The best-fit spectrum yields an intensity of 2.9 photons/sq cm per sec per sterad over the 2-10 keV range. The 3-sigma upper limit to any emission in a 1.5 keV band centered at 7 keV from galactic latitudes not greater than 3.5 deg is 0.3 photons/sq cm per sec per sterad. Several possible emission models are evaluated, with the most likely choice being a population of unresolvable low-luminosity sources.

Bleach, R. D.↗