Engineering topics

Berthiaume, G. D.

Publications and source records attributed to Berthiaume, G. D..

4 records

NASA NTRS1994

CCD soft X-ray observations of the Puppis a supernova remnant

We present the first images and spectra of an astronomical object, other than the Sun, acquired with a charge coupled device (CCD) imaging X-ray spectrometer. During a 230 s sounding rocket observation, we have acquired moderate-resolution spectra and moderate-resolution images of a portion of the Pup A supernova remnant (SNR). Based on these data, we conclude that the X-ray spectrum of Pup A is inconsistent with any single-temperature equilibrium or nonequilibrium plasma model. We find evidence for variations in the emitting plasma on scales as small as 5.0 min and as large as 30.0 min. The spatial structure of the spectral variations in the remnant is found to be inconsistent with the standard Sedov model for the evolution of a SRN into a homogeneous interstellar medium (ISM). We suggest that the remnant is expanding into a region of the ISM having a density of approximately 1 cm(exp -3) with inhomogeneities on the order of 50%. We have found evidence for the presence of a knot of plasma enriched in neon, but require more data to be conclusive.

Berthiaume, G. D.↗

NASA NTRS1992

X-ray observations of planetary nebulae with binary nuclei

Einstein and EXOSAT satellite observations of X-ray emission from the planetary nebulae A63 and LoTr 5 are reviewed. Both of these systems contain binary central stars. No flux was detected from A63 (central star UU Sge). LoTr 5 (central star IN Com) is a previously unreported X-ray emitter; it showed no statistically significant X-ray variability. Three models for the source of the X-ray emission in such systems are considered in the light of these and previous results.

Apparao, K. M. V.↗

NASA NTRS1991

Charge coupled devices (CCDs) in X-ray astronomy

The application of CCDs to X-ray imaging and spectroscopy in astronomy is discussed with special attention given to the special requirements of CCDs for X-ray astronomy (as opposed to those for traditional optical applications). The development status of CCDs for X-ray astronomy applications is described, and results of recent research in the area of optimizing the CCD X-ray response are presented. It is shown that very high quantum efficiencies and Fano noise-limited energy resolutions can be obtained using CCDs.

Lumb, D. H.↗

NASA NTRS1989

Search for soft X-ray emission from SN 1987A with a CCD X-ray imaging spectrometer

The results of soft X-ray observations of SN 1987A over the energy band 0.65-2.0 keV are reported. The upper limits on the soft X-ray flux are inconsistent with an extrapolation of the spectrum measured by the Ginga Satellite to the energy band and require a turnover in the X-ray spectrum between 2 and 4 keV. If this turnover is due to absorption by intervening material, a neutral column density associated with the supernova of at least 2.8 x 10 to the 21st/sq cm is required. The background rate for the Texas Instruments 800 x 800 pixel CCD, measured between 150 and 285 km altitude, was 1.1 counts/sq cm s. The background spectrum has a broad peak at 350 electrons, corresponding to charge deposited in the detector by minimally ionizing particles.

Burrows, D. N.↗