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Tananbaum, H.

Publications and source records attributed to Tananbaum, H..

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Observations of the extended X-ray sources in the Perseus and Coma clusters from Uhuru.

The X-ray source in Perseus identified as NGC 1275 is found to have a finite angular extent of about 35 arc minutes. The improved location of the center of the emission is consistent with NGC 1275. An improved location for the center of the Coma X-1 source is consistent both with the kinematic center of the cluster and with NGC 4874. These extended sources - Coma, Perseus, and the source in the Virgo cluster - may be a new class of X-ray objects associated with active galaxies in rich clusters.

Forman, W.↗
NASA NTRS1972

Discovery of the binary nature of SMC X-1 from Uhuru.

The X-ray source in the Small Magellanic Cloud SMC X-1 was observed by Uhuru on numerous occasions from December 1970 through April 1972. As previously reported by Leong et al. (1971), the source was seen to be variable. It was found that SMC X-1 occults with a period of 3.8927 days. The energy spectrum is cut off at low energies and flat. There is no large-amplitude periodic pulsation. The luminosity observed makes the binary source SMC X-1 comparable in strength to both the stronger galactic sources and the discrete sources in the Large Magellanic Cloud.

Schreier, E.↗
NASA NTRS1972

Observations of Cygnus X-3 by Uhuru.

Report on the X-ray intensity observations of Cygnus X-3 performed with the aid of the X-ray satellite, Uhuru, before and during the radio flare of early September 1972. An analysis of 32 transits of the source, obtained during the period August 19 to September 6, is presented. There is no indication of an intensity change coincident with the radio flare. It is concluded that whatever precipitated the radio flare did not have a significant impact on the X-ray emitting region. Other characteristics of Cyg X-3 are also discussed.

Parsignault, D. R.↗
NASA NTRS1972

Discovery of a periodic pulsating binary X-ray source in Hercules from Uhuru.

We have discovered a new pulsating X-ray source with a 1.24-sec period in the constellation Hercules. Analysis of 5 months of data has shown the existence of periodic variations in the intensity of the source and correlated sinusoidal variations in the period of the 1.24-sec pulsations. As in the case of the pulsating X-ray source Cen X-3, we interpret this effect as due to an occulting binary system, with the intensity changes due to occultation of the X-ray source by its companion and with the sinusoidal variations in the period of the 1.24-sec pulsations due to the Doppler effect. In addition, we have observed a longer-time scale cycle in which the source is bright and pulsing for approximately 9 days during which we can observe the 1.7-day occulting, followed by approximately 27 days during which the source is not detected above background on individual 20-sec scans.

Tananbaum, H.↗
NASA NTRS1972

The extended X-ray source at M87.

It is shown that the X-ray source in Virgo must be intimately associated with the galaxy M87, as evidenced by the coincidence of the source centroid location with the galaxy. Although the presented results do not completely explain the origin of the X rays from the Virgo cluster, they do indicate that the bulk of the emission does not come from the nucleus or the jet, and they also indicate the presence of strong energy processes in a region surrounding M87. One view of the origin of these X rays is that they are due to relativistic electrons ejected from M87, and interacting with magnetic or radiation fields in intergalactic space by the synchrotron of inverse Compton process. The other view holds that the X rays could be due to thermal emission from a hot plasma.

Kellogg, E.↗
NASA NTRS1972

X-ray emission from rich clusters of galaxies.

Evaluation of the newly published Uhuru catalog, revealing significant number of rich clusters associated with X-ray sources. Combined with earlier observations of X-ray emission from the Virgo, Coma, and Perseus clusters, this suggests that most, if not all, rich clusters include an X-ray emission region of large size and of net luminosity from 10 to the 43rd to 10 to the 44th ergs/sec.

Gursky, H.↗
NASA NTRS1972

Evidence for the binary nature of Centaurus X-3 from Uhuru X-ray observations.

Analysis of data spanning a year of observations of the pulsating X-ray source Cen X-3 from Uhuru has revealed the existence of periodic variations in intensity of the source and correlated sinusoidal variations in the period of the 4.8-sec pulsations. We interpret this effect as due to an occulting binary system. The changes in intensity are then due to occultation of the X-ray source by a large massive companion, and the sinusoidal variations in the period of the 4.8-sec pulsations are due to Doppler effect. Physical parameters for the system are derived, and evidence for the existence and nature of an extended atmosphere surrounding the massive occulting object is discussed.

Schreier, E.↗
NASA NTRS1971

X-ray emission from the Magellanic Clouds observed by Uhuru.

Description of three sources in the Large Magellanic Cloud and one in the Small Cloud which have been discovered by Uhuru. These sources each emit about 10 to the 38th erg/sec in the 2- to 7-keV band, and they account for more than 90% of the total emission from the Clouds. The source in the Small Cloud shows time variability on time scales of hours.

Leong, C.↗
NASA NTRS1971

Further observations of the pulsating X-ray source Cygnus X-1 from Uhuru.

Since the discovery of the pulsations from the X-ray source Cygnus X-1 more data from Uhuru have been analyzed. The conclusions reached about the temporal behavior of the source are described. Large fluctuations of intensity exist on all observed time scales ranging from 50 msec to 10 sec containing up to 50 per cent of the power. Periodic pulse trains with periods from 0.3 sec to over 10 sec exist containing 10-25 per cent of the power; however, they persist only for several seconds or several tens of seconds. No single period is consistently present. This behavior is shown to reconcile the apparently contradictory results obtained by other observers. The energy spectrum of the source is best fitted by a power law, but with great variability in the spectral index and with an excess of flux at higher energies.

Schreier, E.↗