Science Archives Publication System

Rapid short-term pulse-period variations in Vela X-1 (4U 0900-40)

DOI: 10.1016/0273-1177(84)90057-7 Bibcode: 1984AdSpR...3j..39V

van der Klis, M.; Bonnet-Bidaud, J. M.

Results are presented of an analysis of 83 days of 2-12 keV X-ray observations of Vela X-1 (4U 0900-40) obtained during three separate pointings with the ESA COS-B satellite. The pulsation period is shown to undergo very rapid intrinsic changes, at a rate of up to P˙/P ~ 10^-1 yr^-1 during intervals of a few days. The lower val…

1984 • Advances in Space Research

COS-B 2

Ultraviolet spectrophotometry of isolated galaxies.

Bibcode: 1984A&A...135..330B

Brosch, N.; Greenberg, J. M.; Rahe, J. +1 more

The authors have obtained ultraviolet spectrophotometry of five isolated galaxies with the IUE which confirms the existence of the ultraviolet excesses first found by UBV photometry. Observations from the optical part of the spectrum to the radio bands are combined with the ultraviolet data to explain the nature of the UV excesses as the signature…

1984 • Astronomy and Astrophysics

IUE 2

A superluminous object in the Large Cloud of Magellan

DOI: 10.1038/scientificamerican0884-52 Bibcode: 1984SciAm.251b..52M

Savage, B. D.; Cassinelli, J. P.; Mathis, J. S.

The superluminous object R136a of the nebula 30 Dor in the Large Cloud of Magellan is characterized, summarizing the results of recent optical and (IUE) UV observations. Photographs, spectra, and diagrams are provided; and the techniques used to determine the parameters of the object are explained. The UV spectra exhibit a typical P Cygni profile …

1984 • Scientific American

IUE 1

Epsilon Aurigae

DOI: 10.1038/scientificamerican1084-98 Bibcode: 1984SciAm.251d..98H

Hack, M.

The results of recent ultraviolet and deep infrared observations of the latest eclipse of the binary Epsilon Aurigae are reported. The observations were performed with both the International Ultraviolet Explorer (IUE) satellite, and with the three-meter Infrared Telescope at Mauna Kea, Hawaii. On the basis of new theoretical models, several explan…

1984 • Scientific American

IUE 1

EXOSAT observation of 'Geminga'

DOI: 10.1007/BF02573801 Bibcode: 1984NCimC...7..748C

Caraveo, P. A.; Bignami, G. F.

IE 0630 + 178, the X-ray source associated with the gamma-ray source Geminga (2CG195 + 04), has been observed by the EXOSAT satellite. The X-ray images, recorded by the channel-multiple-array instruments at the foci of the two low-energy telescopes equipped with different filters, show clearly the source. The flux value, computed from the count ra…

1984 • Nuovo Cimento C Geophysics Space Physics C

Exosat 1

The European X-ray Astronomy Satellite EXOSAT: programme status.

DOI: 10.1088/0031-8949/1984/T7/052 Bibcode: 1984PhST....7..216P

Peacock, A.

The current status of the European X-ray Astronomy Satellite programme, EXOSAT, which includes the payload, spacecraft and ground segment are summarised. Details of the experiment performances and sensitivities are provided.

1984 • Physica Scripta Volume T

Exosat 1

The radial distribution of gamma rays and cosmic rays in the outer Galaxy

DOI: 10.1016/0273-1177(84)90067-X Bibcode: 1984AdSpR...3j..83H

Hermsen, W.; Bloemen, J. B. G. M.; Blitz, L.

The radial distribution of the high-energy (70 MeV-5 GeV) gamma-ray emissivity in the outer Milky Way is derived. The kinematics of HI are used to construct column-density maps in three galacto-centric distance ranges in the outer Galaxy. These maps are used in combination with COS-B gamma-ray data to determine gamma-ray emissivities in these dist…

1984 • Advances in Space Research

COS-B 1

Radial velocity of HD 77581 (Vela X-1) in the period of 1972 - 1983.

Bibcode: 1984PASJ...36..715S

Matsuoka, M.; Sadakane, K.; Jugaku, J.

The radial velocity of HD 77581 (Vela X-1 = 4U 0900-40) was derived from photospheric Fe Iv and Fe II lines observed by the International Ultraviolet Explorer (IUE) satellite in the period 1978-1983. No long-term variation in the radial velocity of 30 km/s was observed. It is shown that the absence of variation effectively rules out the possibilit…

1984 • Publications of the Astronomical Society of Japan

IUE 1

The galactic distribution of cosmic-ray particles

DOI: 10.1016/0273-1177(84)90337-5 Bibcode: 1984AdSpR...4b.393H

Hermsen, W.; Bloemen, J. B. G. M.

COS-B gamma-ray observations are compared with large-scale HI and CO surveys in different regions of the sky to derive information on the cosmic-ray density distribution throughout the Galaxy and/or a calibration of the ratio between H₂ column density and integrated CO line intensity [N(H₂)/W_co]. In the region of t…

1984 • Advances in Space Research

COS-B 0

Broad-band X-ray spectrum of the bright Seyfert galaxy MKN 509

DOI: 10.1007/BF02573809 Bibcode: 1984NCimC...7..864M

Molteni, D.; Robba, N. R.; Sacco, B. +1 more

One of the brightest X-ray Seyfert galaxies, Mkn 509, has been observed with the X-ray satellite EXOSAT. Wide-band (0.05 - 35 keV) spectral information is now available at the same time. Different filters have been rotated in front of the low-energy telescope. The overall spectrum is best fitted by a two-component power law. The intensity and the …

1984 • Nuovo Cimento C Geophysics Space Physics C

Exosat 0