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Gorenstein, P.

Publications and source records attributed to Gorenstein, P..

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Sealed position sensitive hard X-ray detector having large drift region for all sky camera with high angular resolution

A sealed position sensitive proportional counter filled with two atmospheres of 95% xenon and 5% methane, and containing a drift region of 24 atm cm, has operated in a stable manner for many months. The detector contains G-10 frames to support the anode and cathode wires. The detector was sealed successfully by a combination of vacuum baking the G-10 frames at 150 C for two weeks followed by assembly into the detector in an environment of dry nitrogen, and the use of passive internal getters. The counter is intended for use with a circumferential cylindrical collimator. Together they provide a very broad field of view detection system with the ability to locate cosmic hard X-ray and soft gamma ray sources to an angular precision of a minute of arc. A set of instruments based on this principle have been proposed for satellites to detect and precisely locate cosmic gamma ray bursts.

Gorenstein, P.↗
NASA NTRS1979

X-ray structure of clusters of galaxies

Observations of the X-ray structure of the Virgo and Coma clusters of galaxies are described which were made with a two-dimensional imaging X-ray telescope in a series of sounding-rocket flights. It is shown that the X-ray structure of these two clusters exhibits considerable variations in surface brightness, that the central region of the Coma cluster exhibits local variations in surface brightness or clumpiness, and that the centroid of the X-ray emission from the Coma cluster is near the supergiant elliptical galaxy NGC 4874 and is a local minimum in intensity. Positive evidence is obtained for the Fe XXVII-XXIV complex of lines in the spectrum of M87 in the Virgo cluster. It is suggested that the gas in the halo of M87 is isothermal and contains an iron abundance that is uniformly close to the cosmic value.

Gorenstein, P.↗
NASA NTRS1979

X-ray optics for the LAMAR facility, an overview

The paper surveys the Large Area Modular Array of Reflectors (LAMAR), the concept of which is based on meeting two major requirements in X-ray astronomy, large collecting area and moderately good or better angular resolution for avoiding source confusion and imaging source fields. It is shown that the LAMAR provides the same sensitivity and signal to noise in imaging as a single large telescope having the same area and angular resolution but is a great deal less costly to develop, construct, and integrate into a space mission. Attention is also given to the LAMAR modular nature which will allow for an evolutionary development from a modest size array on Spacelab to a Shuttle launched free flyer. Finally, consideration is given to manufacturing methods which show promise of making LAMAR meet the criteria of good angular resolution, relatively low cost, and capability for fast volume production.

Gorenstein, P.↗
NASA NTRS1978

Soft X-ray structure of the Perseus cluster of galaxies

A 0.5-1.5-keV X-ray image of the Perseus cluster of galaxies was obtained with a focusing telescope system aboard a sounding rocket. The source consists of a region of diffuse emission plus a superposed central source in the vicinity of NGC 1275 smaller than 4 arcmin in diameter that accounts for one-quarter of the total intensity within a radius of 25 arcmin. The results for the diffuse source are consistent with the isothermal-hydrostatic picture in which the hot gas has a core radius of 17 arcmin and is approximately symmetric about NGC 1275. Several isothermal-hydrostatic models are considered which relate the size and temperature of the diffuse X-ray source with the core radius of the galaxies and their velocity dispersion. Fixing the velocity dispersion at values measured by Chincarini and Rood (1971) requires the core radius of the galaxies to be 28 + or - 9 arcmin, which is larger than present measurements. Conversely, fixing the core radius of the galaxies at 8 arcmin requires a smaller velocity dispersion or a condition in which the velocity distribution is anisotropic. Upper limits on the intrinsic X-ray absorption of the central source place the bulk of its X-ray emission beyond the nuclear region of NGC 1275.

Gorenstein, P.↗
NASA NTRS1977

Structure of the X-ray source in the Virgo cluster of galaxies

High-angular-resolution observations in the 0.15-1.5-keV band with an imaging X-ray telescope shows the extended X-ray source in the Virgo cluster of galaxies to be a diffuse halo of about 15 arcmin core radius surrounding M87. The angular structure of the surface brightness is marginally consistent with either of two simple models: (1) an isothermal (or adiabatic or hydrostatic) sphere plus a point source at M87 accounting for 12% of the total 0.5-1.5-keV intensity or (2) a power-law function without a discrete point source. No evidence for a point source is seen in the 0.15-0.28-keV band, which is consistent with self-absorption by about 10 to the 21st power per sq cm of matter having a cosmic abundance. The power-law models are motivated by the idea that radiation losses regulate the accretion of matter onto M87 and can account for the observed difference in the size of the X-ray source as seen in the present measurements and at higher energies.

Gorenstein, P.↗
NASA NTRS1977

Large-area soft X-ray imaging system

System consists of large-area focusing collector and position sensitive proportional counter. Device can be used to study plasmas, with X-ray imaging in biological sciences, and crystallography.

Gorenstein, P.↗
NASA NTRS1977

A soft X-ray image of the Algol region

Algol (Beta Persei) has been detected in two separate exposures of an imaging X-ray telescope. The 0.15- to 2-keV X-ray luminosity is approximately 2 by 10 to the 30th power erg/s. The X-ray flux is interpreted as thermal emission produced by direct accretion of mass from the K star to the B8 member of the triple star system.

Harnden, F. R., Jr.↗
NASA NTRS1975

The Apollo 15 and 16 X-ray fluorescence experiment

An X-ray fluorescence spectrometer was flown aboard the Apollo 15 and 16 spacecrafts orbiting the moon. The X-ray instrument was used to produce a chemical map of that portion of the moon covered by the projected ground tracks and illuminated by the sun during the period of flight. The instrument includes three thin windowed proportional counters, two of which have selected X-ray filters. The field of view of the surface is determined by a collimator, while a detector on the opposite side of the spacecraft provides a continuous monitoring of the solar X-ray output. While the number of chemical elements determined was limited to Mg, Al, and Si, these proved to be very important diagnostic elements.

Adler, I.↗
NASA NTRS1975

Empirical relation between interstellar X-ray absorption and optical extinction

An empirical relation between interstellar X-ray absorption and optical extinction is derived from the correlation of measurements made on objects of large intrinsic diameter. The result is Av = 4.5 times 10 to the -22nd power N(H) mag, with the principal error being largely systematic in origin, where N(H) represents the column density of interstellar matter in the Brown and Gould model for the X-ray absorption coefficient. Applying this ratio to optically identified compact sources, it is concluded that sources in binary systems showing pronounced X-ray occultations have an intrinsic absorption equivalent to about 10 to the 22-nd power atoms per sq cm of interstellar matter and that there are a few compact sources where the absorption seems to be primarily interstellar in origin. The interstellar absorption expected in Cyg X-1 from the extinction of its optical counterpart is much greater than that suggested by X-ray spectra, which may be due to a soft X-ray component greater than that predicted by the power law fitted to higher energy data.

Gorenstein, P.↗
NASA NTRS1974

Compact source of soft X-rays

Sources of soft X-rays uses alpha particles to fluoresce light elements such as boron, carbon, and magnesium. X-ray wavelengths are varied by changing target. Technique supplies broad range of monoenergetic X-rays whose energy can be adjusted very easily.

Gorenstein, P.↗
NASA NTRS1974

Observation of a cosmic gamma-ray burst on Apollo 16. II - X-ray time profile and source location

A burst of X-rays was detected during the trans-earth coast phase of Apollo 16 on Apr. 27, 1972 at 10:68 UT, simultaneously with the observation of a transient event by a gamma-ray spectrometer aboard the same spacecraft. The two instruments provide a broad energy range of more than three orders of magnitude for describing the spectral distribution of this event. The conclusion that the incident flux was X-rays and not charged particles is based on the fact that the particle flux detectors in the Apollo gamma ray spectrometer and on the Vela 6A, which also observed the event, did not respond. The time variation of the total count rate in the X-ray range before and after corrections for detector geometry and the analysis for source direction is presented.

Trombka, J. I.↗
NASA NTRS1974

The X-ray spectra of the Vela and Puppis supernova remnants and the shock-wave model of supernova remnants

The structure and spectrum of the Vela and Puppis supernova remnants (SNRs) were observed in soft (0.1 to 1.5 keV) X rays from a rocket. The spectral data of both objects below 1.5 keV are consistent with thermal radiation from a hot plasma and are not consistent with a simple power-law function. Fitting the data to a Tucker-Koren model results in values of T = (4.3 plus or minus 0.3) x 1,000,000 K for Vela and T = (7 plus or minus 1) x 1,000,000 K for Puppis. The present data, earlier data from the Cygnus Loop, and results on Cas A and Tycho reported by others are considered within the context of a simple model in which X rays are thermally produced as a result of a shock wave expanding into the interstellar medium. X-ray data on the temperature, intrinsic diameter, and intrinsic luminosity of the five SNRs are used to compute the age, energy release, and initial interstellar density for each one. From measurements of X-ray absorption along the line of sight, and also from shock-wave model interpretations of temperature-diameter-luminosity relations, it is concluded that the average density of interstellar material is about 0.1 per cu cm between the sun and the nearest X-ray emitting SNR, Vela.

Gorenstein, P.↗
NASA NTRS1974

Detection of radon emission at the edges of lunar maria with the Apollo alpha-particle spectrometer

The distribution of radioactive polonium-210, a decay product of radon-222, shows enhanced concentrations at the edges of lunar maria. Enhancements are seen at the edges of Mare Fecunditatis, Mare Crisium, Mare Smythii, Mare Tranquillitatis, Mare Nubium, Mare Cognitum, and Oceanus Procellarum. The observation is indicative of the transient emission of radon gas from the perimeters of lunar maria.

Gorenstein, P.↗
NASA NTRS1973

Large area focusing collector for the observation of cosmic X rays.

A large area focusing X-ray collector constructed for a sounding rocket is described. The instrument consists of nested reflecting plates that are curved slightly in one dimension to form a set of parabolas with a common focus. An array of plates such as the one in the sounding rocket focuses a parallel beam of X-rays to a line. The reflecting surfaces are commercial float glass with an evaporated metallic coating such as gold or nickel. With a gold coating, the effective area of the rocket collector is about 250 sq cm for 0.3 keV X rays and about 150 sq cm at 1.2 keV. Its angular resolution is a few arc minutes and field of view is about plus or minus .75 deg (full width at half maximum). The collector performed successfully during a sounding rocket flight.

Gorenstein, P.↗