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Ultraviolet Observations of the X-Ray Sources in the Eta-Carinae Nebula

Macchetto, F.; Viotti, R.; Cassatella, A. +1 more

η Car is surrounded by a dense nebula ejected during the last 150 years. The Einstein satellite recently detected intense X-ray emission from η Car and its nebula indicating the existence of efficient gas heating processes. Ultraviolet observations with IUE confirmed the presence of hot gas in the condensation S of the nebula and in η Car. Possibl…

An Optical Outburst from the Periodic Recurrent X-Ray Transient A0538-66

Charles, P. A.; Willis, A. J.; Thorstensen, J. R. +2 more

We present optical spectroscopy and photometry and IUE spectroscopy of the counterpart of the LMC recurrent X-ray transient A0538-66 during an outburst at the end of December 1980 which was consistent with the 16.6 day X-ray period (Skinner, 1980). The optical spectra show steadily increasing Balmer and HeI emission (indicative of a shell phase) s…

Ultraviolet Study of U1341-CYGNI = CYGNUS-X-2 - Observations of an Accretion Disk

Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +1 more

Observations of Cyg X-2 with the International Ultraviolet Explorer in the range 1200-3000 A are discussed with particular reference to the continuum. The dereddened UV spectrum indicates the presence of a contribution from a hot region of small area which is naturally interpreted as an X-ray heated accretion disk. Assuming an average X-ray lumino…

Is PKS 2155 an extragalactic source?

Maraschi, L.; Tanzi, E. G.; Tarenghi, M. +1 more

The X-ray source H2155-304, identified with the radio source PKS 2155 and with a 14 mag star-like object, is commonly believed to be a BL Lac object on the basis of the blue featureless continuum, the presence of optical polarization, and the violent variability (m_B varies from 12.8 to 14.2 on a time scale of months). This paper present…

First Ultraviolet Observations of the Optical Couterpart of the X-Ray Source 2S0114+650

Bianchi, L.

The X-Ray Source 2S0114+650 discovered by SAS-3 in 1978 has been associated with a highly reddened star showing broad H_α emission. We observed this star with the LWR spectrograph on board the I.U.E. Satellite on Sep. 1980 and Feb. 1981. An Ultraviolet flux was detected longward of the 2200 Å bump, consistent with the B0.5 spectral class…

Cos-B X-Ray Observations of CYGNUS-X-3 - an Indications for Apsidal Motion

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

Results are presented of three ∼40 d COS-B X-ray observations of Cyg X-3. The shape of the 4.8 h light curve showed variations on all observational time scales. An ∼20 d periodicity was found in the arrival time of the minimum of the light curve, interpreted as apsidal motion of an orbit with an eccentricity of ∼0.03.

Ultraviolet Observations of Mv-Lyrae

Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +1 more