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Schultz, A. B.

Publications and source records attributed to Schultz, A. B..

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

An EXOSAT detection of the transient X-ray pulsar GRO J1008-57

The hard X-ray transient, GRO J1008-57, was discovered during a bright outburst in 1993 July by the Burst and Transient Source Experiment (BATSE) instrument on board the Compton Gamme-Ray Observatory (CGRO). There are no published reports of previous emission from this 93.6 sec X-ray pulsar. Recent optical results have suggested a Be star as the companion. A search of the EXOSAT archives shows that an ME observation centered on the star HD 88661 includes GRO J1008-57 within the field of view. The characteristics of the medium-energy detection including a hard spectrum and pulsed emission at 91.36 sec (with chance probability of 3 x 10(exp -4)) indicates that EXOSAT detected GRO J1008-57 rather than the field star. The estimated flux is 2.4 x 10(exp -11) ergs/cm sq/sec for a luminosity of 1.1 x 10(exp 34) (D/2 kpc)(exp 2) ergs/sec. The X-ray spectrum is hard (photon index approximately equals 1.2) and highly absorbed (N(sub H) approximately equals 0.7 x 10(exp 22)). The detection of this transient suggests that there is a pulse shape dependence on luminosity, a spectral shape independent of luminosity, a large period derivative of P-dot/P = 2.3 x 10(exp -3)/yr, and a dynamic range of at least 100 in L(sub chi). We discuss GRO J1008-57 data in the context of wind-accretion models for this new member of the Be class of X-ray binaries.

Macomb, D. J.↗
NASA NTRS1991

The structure of Io's corona

A spatial profile of the distribution of sodium in Io's corona has been constructed using measurements obtained during satellite mutual eclipses. The data reveal a fairly symmetric corona whose density falls steeply from the surface out to 6 r(Io) and more slowly outside. An upper limit of 700 km is placed on the exobase altitude, but the observations do not constrain the surface density. Several theoretical models adequately match some traits of the corona, but none satisfies all the observations. No strong upstream/downstream asymmetry of the corona is observed, so it is unlikely that the corona is primarily generated by the impact of corotating ions into the trailing hemisphere.

Schneider, N. M.↗
NASA NTRS1990

Color maps of Arp 146

Four color maps of Arp 146 are given. The structure and color of the ring galaxy and its companion show evidence of a bridge of material between the companion and the remnant nucleus of the original galaxy now forming the ring. Broad band spatial coverage clearly defines regions of starburst occurrence.

Schultz, A. B.↗