Engineering topics

Rose, L. A.

Publications and source records attributed to Rose, L. A..

6 records

NASA NTRS1980

The diffuse X-ray background spectrum from 3 to 50 keV

The spectrum of the extragalactic diffuse X-ray background has been measured with the GSFC Cosmic X-ray Experiment on HEAO 1 for regions of the sky away from known point sources and more than 20 deg from the galactic plane. A total exposure of 80 sq m-s-sr is available at present. Free-free emission from an optically thin plasma of 40 plus or minus 5 keV provides an excellent description of the observed spectrum from 3 to 50 keV. This spectral shape is confirmed by measurements from five separate layers of three independent detectors. With an estimated absolute precision of about 10%, the intensity of the emission at 10keV is 3.2 keV/keV/sq cm/s/sr, a value consistent with the average of previously reported spectra. A uniform hot intergalactic medium of approximately 36% of the closure density of the universe would produce such a flux, although nonuniform models indicating less total matter are probably more realistic.

Marshall, F. E.↗

NASA NTRS1979

Laboratory simulation of infrared astrophysical features

Laboratory infrared emission and absorption spectra have been taken of terrestrial silicates, meteorites, and lunar soils in the form of micrometer and submicrometer grains. The emission spectra were taken in a way that imitates telescopic observations. The purpose was to see which materials best simulate the 10-micron astrophysical feature. The emission spectra of dunite, fayalite, and Allende give a good fit to the 10-micron broadband emission feature of comets Bennett and Kohoutek. A study of the effect of grain size on the presence of the 10-micron emission feature of dunite shows that for particles larger than 37 microns no feature is seen. The emission spectrum of the Murray meteorite, a Type 2 carbonaceous chrondrite, is quite similar to the intermediate-resolution spectrum of comet Kohoutek in the 10-micron region. Hydrous silicates or amorphous magnesium silicates in combination with high-temperature condensates, such as olivine or anorthite, would yield spectra that match the intermediate-resolution spectrum of comet Kohoutek in the 10-micron region. Glassy olivine and glassy anorthite in approximately equal proportions would also give a spectrum that is a good fit to the cometary 10-micron feature.

Rose, L. A.↗

NASA NTRS1979

Observations of the transient X-ray source 4U 0115+63

Results are presented for HEAO A-2 pointed observations and Ariel 5 A11-Sky Monitor observations of the X-ray transient 4U 0115 + 63. The transient source pulses with a period of 3.6136 s + or - 0.0004 s, has a hard spectrum typical of an X-ray binary pulsar, and has a broad iron line emission feature. A discussion of the transient behavior is given, and inferences are made concerning the nature of the X-ray source based on the pointed data.

Rose, L. A.↗

NASA NTRS1979

The diffuse X-ray background spectrum from 3 to 50keV

The spectrum of the extragalactic diffuse X-ray background was measured with the GSFC cosmic X-ray experiment on HEAO-1 for regions of the sky away from known point sources and more than 20 deg from the galactic plane. A total exposure of 80 sq m-sec-sr is available at present. Free-free emission from an optically thin plasma of 40 plus or minus 5 keV provides an excellent description of the observed spectrum from 3 to 50 keV. This spectral shape is confirmed by measurements from 5 separate layers of three independent detectors. With an estimated absolute precision of about 10 percent, the intensity of the emission at 10 keV is 3.2 keV/keV-sq cm-sec-sr, a value consistent with the average of previously reported spectra. No other spectral features, such as iron line emission, are evident. This spectrum is not typical of known extragalactic objects. A uniform hot intergalactic medium of approximately 36 percent of the closure density of the universe would produce such a flux, although non-uniform models indicating less total matter are probably more realistic.

Marshall, F. E.↗

NASA NTRS1979

Observations of the transient X-ray source 4U0115+63

Results of HEAO-2 pointed observations and Ariel 5 All Sky Monitor observations of the X-ray transient 4U0115+63 are presented. The transient source pulses with a period of 3.6136 s + or - .0004 s, has a hard spectrum typical of an X-ray binary pulsar, and has a broad iron line emission feature. A discussion of the transient behavior is given and inferences are made concerning the nature of the X-ray source based on the pointed data.

Rose, L. A.↗

NASA NTRS1977

Laboratory simulation of infrared astrophysical features

Intermediate resolution emission spectroscopy was used to study a group of 9 terrestrial silicates, 1 synthetic silicate, 6 meteorites and 2 lunar soils; comparisons were made with the intermediate resolution spectra of Comet Kohoutek in order to determine which materials best simulate the 10um astrophysical feature. Mixtures of silicates which would yield spectra matching the spectrum of the comet in the 10um region include: (1) A hydrous layer lattice silicate in combination with a high temperature condensate; (2) an amorphous magnesium silicate in combination with a high temperature condensate and (3) glassy olivine and glassy anorthite in approximately equal proportions.

Rose, L. A.↗