High resolution muonic X-ray studies
High resolution muonic X-ray studies on nuclear isotope interactions
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Cosmic X-ray physics
A progress report of research activities carried out in the area of cosmic X-ray physics is presented. The Diffuse X-ray Spectrometer DXS which has been flown twice as a rocket payload is described. The observation times proved to be too small for meaningful X-ray data to be obtained. Data collection and reduction activities from the Ultra-Soft X-ray background (UXT) instrument are described. UXT consists of three mechanically-collimated X-ray gas proportional counters with window/filter combinations which allow measurements in three energy bands, Be (80-110 eV), B (90-187 eV), and O (e84-532 eV). The Be band measurements provide an important constraint on local absorption of X-rays from the hot component of the local interstellar medium. Work has also continued on the development of a calorimetric detector for high-resolution spectroscopy in the 0.1 keV - 8keV energy range.
Mccammon, D.↗
Requirements for high quality X-ray spectroscopy in an Explorer class mission
Through the use of simulated X-ray spectra the question of instrument requirements for a spectrograph that could significantly advance X-ray astronomy is addressed. It it concluded that resolution (lambda/delta lambda) in the range of 200 to 500, and effective collecting area in excess of 200 sq cm are required. One design, based on the objective reflection grating concept, which would meet these stringent requirements in an Explorer class mission is presented.
Cash, W. C., Jr.↗
Stellar crystal X-ray spectroscopy on OSO-8
The large-area graphite crystal X-ray spectrometer on the OSO-8 satellite is described, and its response to stellar line and continuum radiation is discussed. A high resolution X-ray spectrum of Sco X-1 obtained from a preliminary analysis of quick look data shows a strong, smooth continuum with an absence of emission or absorption features over the energy range 2.2 to 8 keV. Upper limits are set on narrow line emission from highly ionized states of S, Ca, and Fe.
Kestenbaum, H. L.↗
Phase resolved optical spectroscopy of the compact X-ray binary 2A1822-371
The optical, X-ray, and ultraviolet emissions of the X-ray system 2A1822-371 are modulated with a period of 5.57 hr. The 5.57 hr modulation is believed to reflect orbital motion about a mass donating companion star. The modulation at high energies is caused by the combined effects of an occultation by the companion and by a bulge on the accretion disk. The present investigation is concerned with an extension of the study of 2A1822-371, taking into account medium resolution optical spectroscopy of the system covering the 5.57 hr cycle. Broad shallow absorption lines are observed in the optical spectrum of 2A1822-371. These lines are similar to the rotationally broadened lines which are found in the spectra of disk accreting cataclysmic variables. Their presence in 2A1822-371 is, therefore, strong confirmation that it is a disk accreting star. The He II 4686 A and H-alpha emission lines have a breadth comparable to the absorption lines at all phases in the 5.57 hr cycle.
Mason, K. O.↗
Coronae of nondegenerate single and binary stars: A survey of our present understanding and problems ripe for solution
Information about the coronae of stars in different portions of the HR diagram, and how the characteristics of such coronae compare with what is known about the solar corona are reviewed. For each type of star, some unanswered questions and the generic type of X-ray instrument required to answer these questions are listed. The survey points out the critical need for a sensitive X-ray instrument with both moderate spectra resolution and imaging capability that can monitor selected targets for long periods of time. There is also a need for high spectral resolution, provided sensitivities can be improved greatly over Einstein, and near simultaneous ultraviolet spectroscopy.
Linsky, J. L.↗
Development of high throughput X-ray telescopes for X-ray imaging and dispersive spectrometers
During the past year the technical approach to the realization of a high throughput Kirkpatrick-Baez X-ray mirror became better defined in terms of construction methodology and factors which affect maximum size. More progress was made than anticipated in the area of automatic figure formation. However, effort to improve the resolution of float glass by simple techniques were not successful. Mirror development, spectroscopy, all sky telescope, and explorer concept studies are discussed.
Gorenstein, P.↗
The advanced X-ray Astrophysics Facility (AXAF)
NASA's Advanced X-ray Astrophysics Facility (AXAF) will be an orbiting X-ray observatory, designed to address fundamental questions in astronomy and astrophysics. AXAF is the successor to NASA's second High Energy Astronomy Observatory, the Einstein X-ray Observatory, which operated from 1978 to 1981. Like the Einstein, the AXAF will be built around a grazing incidence telescope capable of forming X-ray images. AXAF, however, will go far beyond the Einstein in capability having about 10 times the angular resolution, about 100 times the sensitivity for imaging, and up to about 1000 times the sensitivity for spectroscopy. The AXAF will operate in space for 15 years, and be maintained and refurbished by use of NASA's Space Station.
Weisskopf, M. C.↗
New X-ray and optical observations of the X-ray discovered QSO-galaxy pair 1E 0104.2 + 3153
New X-ray and optical observations are presented of the QSO-galaxy pair 1E 0104.2 + 3153, originally discovered as a serendipitous source in the Einstein Observatory Medium Sensitivity Survey (Gioia et al., 1984). Results from an extremely deep Exosat observation are used to suggest that the QSO rather than the compact group of galaxies is the optical counterpart of the IPC source. High-resolution (1-A) spectroscopy of the broad-absorption-line QSO, which fails to confirm the Ca II H and K absorption features reported by Stocke et al., (1984), is presented and discussed. The presence of broad absorption lines in the QSO spectrum may indicate that intrinsic absorption is the cause of the nondetection of this source in the soft Exosat energy band. Optical monitoring of the QSO over a 2-yr period indicates variability. Possible interpretations of this phenomenon are intrinsic luminosity variation or a cessation of a gravitational lensing effect acting at the time of the Einstein observation.
Gioia, I. M.↗
Solar flares
A review of the knowledge about solar flares which has been obtained through observations from the earth and from space by various methods. High-resolution cinematography is best carried out at H-alpha wavelengths to reveal the structure, time history, and location of flares. The classification flares in H alpha according to either physical or morphological criteria is discussed. The study of flare morphology, which shows where, when, and how flares occur, is important for evaluating theories of flares. Consideration is given to studies of flares by optical spectroscopy, radio emissions, and at X-ray and XUV wavelengths. Research has shown where and possibly why flares occur, but the physics of the instability involved, of the particle acceleration, and of the heating are still not understood.
Zirin, H.↗
Spectroscopy of the extreme ultraviolet background radiation
Observations in the FUV and soft X-ray bands suggest that the interstellar medium contains several components of high-temperature gas and should be emitting in the EUV. Indeed, diffuse radiation has been detected in the EUV with photometric instruments, but no special measurements exist below 520 A. A unique grazing-incidence spectrometer has been designed to study the diffuse emission between 80 and 650 A with 10 to 20-A resolution. The instrument was launched on a Black Brant sounding rocket from White Sands Missile Range on April 22, 1986. Preliminary analysis shows the expected geocoronal and interplanetary He I 584-A emission, and possibly other features which may originate in the hot ionized interstellar gas. Flux limits to these possible emission lines are compatible with previous broadband measurements.
Labov, Simon↗
Experimental tests of a single-photon calorimeter for X-ray spectroscopy
Tests have been made of a nondispersive spectroscopic X-ray detector which operates by measuring the temperature rise following absorption of a single photon. Thermal pulses from 6-keV X-rays have been observed, and the different amplitudes resulting from Mn K-alpha and K-beta events have been resolved. This device was assembled to make quantitative tests of theoretical calculations of the properties of such detectors, and its high heat capacity does not allow it to attain the very high resolution predicted for detectors made by more sophisticated, but still straightforward, techniques. Both the measured resolution of 270-eV full width at half maximum and the absolute amplitude of the response are consistent with predictions. Nonthermal effects in the thermistor limit the precision of this comparison to about 30 percent.
Mccammon, D.↗
Application of maximum-entropy spectral estimation to deconvolution of XPS data
A comparison is made between maximum-entropy spectral estimation and traditional methods of deconvolution used in electron spectroscopy. The maximum-entropy method is found to have higher resolution-enhancement capabilities and, if the broadening function is known, can be used with no adjustable parameters with a high degree of reliability. The method and its use in practice are briefly described, and a criterion is given for choosing the optimal order for the prediction filter based on the prediction-error power sequence. The method is demonstrated on a test case and applied to X-ray photoelectron spectra.
Vasquez, R. P.↗
Columbia University OSO-8 instrument for stellar and solar X-ray spectroscopy and polarimetry
A spectrometer and a polarimeter consisting of large-area panels of mosaic crystals have been constructed and prepared for use in the OSO-8 satellite. The instrumentation is planned for study of stellar and solar X-ray spectra between 1.8-8 keV and stellar X-ray polarization at 2.6 keV. Aspects of the design which enable the instrument to make measurements of the diverse range of stellar and solar phenomena are described. Some of the unique features, such as high sensitivity, high temporal resolution, and spectral range, are discussed. The applicability of the spectrometer and polarimeter to various current problems in X-ray astronomy is considered.
Wolff, R. S.↗
HEAO A-2 extragalactic results
The all-sky surveys made with the A-2 instrument aboard HEAO-1 involved spectroscopy over a broad enough band width, with sufficient resolution, to obtain the basic spectral characteristics for two extreme aspects of the extragalactic X-ray sky. The overall spectrum (above 3 KeV) is remarkably well decribed by a thermal model. At the other extreme, the detailed broad-band observations of individual sources are restricted to objects within the present epoch. The objects include several individual active galaxies studied in detail for the first time as well as clusters of galaxies. Relating these results to the vast spatially unresolved hard X-ray flux measured with this instruments as well as the softer X-rays (at less than 3 keV) spatially resolved to high redshifts with the Einstein Observatory remains a challenge.
Boldt, E. A.↗
Astronomy satellites in the U.S. program
The Orbiting Astronomical Observatory (OAO) series demonstrated that necessary thermal control systems and high pointing stability are feasible on astronomical satellites. A geosynchronous International Ultraviolet Explorer (IUE) is being planned by the US, UK, and ESRO for stellar spectroscopy. High Energy Astronomy Observatories, HEAO-A B, and C, will concentrate on stellar X-ray objects, cosmic ray physics, and gamma ray astronomy. A Shuttle-compatible Solar Maximum Mission (SMM) is planned for studying solar flares and flare related phenomena during the next solar maximum. Now in the instrumentation definition stage is the Large Space Telescope (LST), to provide higher resolution and sensitivity, larger wavelength range (from ultraviolet to far infrared), and higher time resolution than ground-based telescopes.
Aucremanne, M. J.↗
Future directions in experimental gamma ray astronomy
Better vehicles and instruments are needed if gamma ray spectroscopy in astrophysics and cosmology is to advance. A gamma ray observatory will (1) permit long-term observations of selected sources to measure their variability and to achieve high sensitivity; (2) measure periods in days or weeks; and (3) assess the entire sky to observe various predicted sources, to measure the energy spectrum, and to map the isotropy of the cosmic ray background over larger collecting areas (of the order of a square meter). Conventional and unconventional instruments must cover the energy range from 0.1 MeV to 20 MeV with improved sensitivity. Angular resolution must be improved one degree or more to study discrete X-ray sources in the galactic center. Actively collimated detectors, improved double Compton instruments, and gamma ray correlators to actively synthesize the absolute energy spectrum of the sky protons are discussed as well as the need for scientific balloons.
Haymes, R. C.↗
High resolution X- and gamma-ray spectroscopy of solar flares
A balloon-borne X- and gamma-ray instrument was developed, fabricated, and flown. This instrument has the highest energy resolution of any instrument flown to date for measurements of solar and cosmic X-ray and gamma-ray emission in the 13 to 600 keV energy range. The purpose of the solar measurements was to study electron acceleration and solar flare energy release processes. The cosmic observations were to search for cyclotron line features from neutron stars and for low energy gamma-ray lines from nucleosynthesis. The instrument consists of four 4 cm diameter, 1.3 cm thick, planar intrinsic germanium detectors cooled by liquid nitrogen and surrounded by CsI and NaI anti-coincidence scintillation crystals. A graded z collimator limited the field of view to 3 deg x 6 deg and a gondola pointing system provided 0.3 deg pointing accuracy. A total of four flights were made with this instrument. Additional funding was obtained from NSF for the last three flights, which had primarily solar objectives. A detailed instrument description is given. The main scientific results and the data analysis are discussed. Current work and indications for future work are summarized. A bibliography of publications resulting from this work is given.
Lin, R. P.↗