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Margon, B.

Publications and source records attributed to Margon, B..

87 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

On the distance to Cygnus X-1

Interstellar extinction of 50 stars in the immediate vicinity of Cyg X-1 is compared with color excess of HDE 226868. The fact that HDE 226868 has extinction drastically exceeding that of all stars in the field at less than 1 kpc is believed to be in conflict with the model of Trimble et al. (1973) in which the primary is a luminous undermassive star and with other similar models. Uniform extrapolation of the reddening yields a distance estimate of (2.5 plus or minus 0.4) kpc for Cygnus X-1, in agreement with the spectroscopic modulus for an O9 star.

Margon, B.↗
NASA NTRS1973

Spectroscopic observations of the Cygnus X-1 optical candidate.

Data from nine high-dispersion spectra of HDE 226868, the optical candidate for Cyg X-1, are presented. The line profiles at He II (4686 A) show marked changes from night to night. Our data are not compatible with models where the emission line arises from the unseen secondary component of the system, as has been suggested by other observers. We propose that the emission originates in a gas stream falling toward the secondary; this provides observational evidence that the X-ray source is powered by accretion. We also see changes in spectral type and luminosity class with phase, further complicating attempts to make mass estimates for the system.

Smith, H. E.↗
NASA NTRS1972

IC 3576 - An unusual spiral galaxy in Virgo.

The possible association of an X-ray source with the galaxy IC 3576 was investigated in a program of optical observations of this galaxy. The observations show that patches and condensations belonging to the galaxy are distributed in a nonrandom, spiral fashion. This distinctive morphology corresponds to the dwarf spiral of the second type discussed by van den Bergh (1959). Radio observations are also considered, giving attention to a 21-cm emission due to neutral hydrogen in IC 3576. It is pointed out that the evidence at this time that the X-ray source in Virgo corresponds to IC 3576 is positional only.

Margon, B.↗
NASA NTRS1972

Limits on intergalactic helium from the 3C 273 X-ray spectrum.

An X-ray spectrum of the quasi-stellar object 3C 273 in the interval 0.25-10 keV has been obtained by sounding-rocket observations. The best-fit power-law spectrum has a photon index n = 1.3 with no photoelectric absorption. An upper limit on the X-ray optical depth to 3C 273 has been calculated from the data, permitting upper limits to be set on the absolute abundance of helium in the intergalactic medium.

Margon, B.↗
NASA NTRS1972

The spectra of ten galactic X-ray sources in the southern sky.

Data on 10 galactic X-ray sources located between 320 and 20 deg galactic longitude were obtained during a rocket flight from Brazil in June 1969. Detailed spectra of these sources have been compared with bremsstrahlung, blackbody, and power-law models, each including interstellar absorption. Six of the sources were fitted well by one or more of these models. In only one case were the data sufficient to distinguish the best model. Three of the sources were not fitted by any of the models, which suggests that more complex emission mechanisms are applicable. A comparison of our results with those of previous investigations provides evidence that five of the sources vary in intensity by a factor of two or more, and that three have variable spectra.

Cruddace, R.↗
NASA NTRS1972

On the optical identification of Centaurus X-3.

It is suggested that the previously photographed emission-line star WRA 795 is the optical counterpart of Cen X-3, the X-ray pulsar which is a member of an occulting binary system. The star falls in the X-ray error box, which measures only 0.01 square degrees, and shows strong emission variability on a timescale of days, similar to HDE 226868, the suggested Cyg X-1 counterpart.

Margon, B.↗
NASA NTRS1972

Anomalous minima in Cen X-3.

Report of an observation made with a rocket-borne argon-methane proportional counter, which was equipped with a 'Mylar' window and was sensitive to X rays in the range from 0.2 to 10 keV. During a scan of the galactic plane, the detector passed directly over the location of Cen X-3 at a roll rate of 1 deg per second. An extended minimum of X-ray flux was observed. It is concluded that the anomalous effect is intrinsic to the source.

Margon, B.↗
NASA NTRS1972

Limits on intergalactic helium from the 3C 273 X-ray spectrum

An X-ray spectrum of the quasi-stellar object 3C 273 in the interval 0.25 to 10 KeV was obtained by sounding rocket observations. The best-fit power law spectrum has photon index n= 1.3 with no photoelectric absorption. An upper limit on the X-ray optical depth to 3C 273 was calculated from the data, permitting upper limits to be set on the absolute abundance of helium in the intergalactic medium.

Margon, B.↗
NASA NTRS1972

The X-ray spectrum of NGC 5128.

Evaluation of the X-ray spectrum of NGC 5128 (Cen A) obtained by sounding rocket and balloon observations in the range from 1 to 180 keV. NGC 5128 may be fitted by a power law with a photon index -2 less than or equal to n less than or equal to -1.45. Inverse Compton models are presented, and constraints on their parameters are discussed. In all such models, the electrons and magnetic field have not yet equilibrated. Alternatively, the X rays may originate in a compact central core source.

Lampton, M.↗
NASA NTRS1971

The spectra of ten galactic X-ray sources in the southern sky

Data on ten galactic X-ray sources were obtained during a rocket flight from Brazil in June 1969. Detailed spectra of these sources have been compared with bremsstrahlung, black body, and power law models, each including interstellar absorption. Six of the sources were fitted well by one or more of these models. In only one case were the data sufficient to distinguish the best model. Three of the sources were not fitted by any of the models, which suggests that more complex emission mechanisms are applicable. A comparison of our results with those of previous investigations provides evidence that five of the sources vary in intensity by a factor of 2 or more, and that three have variable spectra. New or substantially improved positions have been derived for four of the sources observed.

Cruddace, R.↗
NASA NTRS1971

X-ray observations of Virgo XR-1

Virgo XR-1 X rays observation with rocket-borne proportional counters, noting photo index or bremsstrahlung temperature consistency with spectrum

Bowyer, S.↗