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Ultraviolet interstellar absorption toward stars in the Small Magellanic Cloud. IV. Highly ionized gas associated with the Small Magellanic Cloud.
Savage, B. D.; Fitzpatrick, E. L.
High-dispersion International Ultraviolet Explorer satellite spectra of seven stars in the Small Magellanic Cloud (SMC) are examined to study the properties of interstellar C IV and Si IV absorption in the SMC. Absorption by C IV or Si IV or both is found near 160 km/s for all the stars. The velocity and the relative C IV and Si IV strengths sugge…
The 2200 A circumstellar dust absorption feature in the spectra of three bright RV Tauri stars.
Cardelli, J. A.; Baird, S. R.
IUE observations of the 2200 A absorption feature of circumstellar dust were made of the three RV Tauri stars AC Her, U Mon, and R Sct. U Mon was found to have a dust shell with a much lower column density at 2200 A than R Sct and possibly AC Her, requiring U Mon to have a much more extended dust shell than R Sct to account for its greater infrare…
Temporal Intensity Fluctuations of HERCULES-X-1 around 100-SECOND Timescales
Pietsch, W.; Kahabka, P.; Truemper, J. +2 more
Her X-1 has been observed with EXOSAT for one 35d cycle between March 1 and April 5, 1984 at about 4 day intervals. During three observations, absorption dips were encountered showing fluctuations with time scales in the several hundred seconds range. The data are interpreted with a model where random superposition of absorbing blobs or…
Simultaneous ultraviolet and optical observations of FK Comae.
Grewing, M.; Bianchi, L.; Kappelmann, N.
The authors report simultaneous photometric and spectroscopic observations of FK Comae. Photometric measurements were made in the UBVR system, and in two bands centered near Hα and Hβ, respectively. The spectroscopic measurements were obtained with the IUE satellite in the 1150 - 3200 Å band near phases 0 and 0.5, in order to distinguish between t…
The first IUE observations of LMC X-1 (star 32).
Pakull, M.; Bianchi, L.
The first far UV observations of LMC X-1 (star 32) are presented. Form the UV continuum distribution the authors derive a value for the reddening towards star 32 of E(B-V) = 0.05 (galactic foreground extinction) plus 0.32 (extinction in the LMC). The dereddened stellar continuum can be reproduced by a model atmosphere with Teff = 35,000…
Alpha Trianguli Australis (K2 II-III) : hybrid or composite ?
Ayres, T. R.
The prototype "hybrid-spectrum" giant, α Trianguli Australis, exhibits a far-ultraviolet continuum which is considerably bluer than would be expected of a star of its optical colors, suggesting the presence of a previously unrecognized companion. If the K type primary is as luminous as indicated by the widths of its Ca II and Hα lines, the compani…
The Big Dipper - 4U1624-49
Halpern, J.; Grindlay, J. E.; King, A. R. +2 more
We present a 6.3 hour observation of 4U1624-49 with the EXOSAT Medium Energy experiment. The X-ray light curve is dominated by a series of sharp dips in which the observed flux falls to ∼25% of the steady level on timescales of seconds. These dips are accompanied by strong variations in the spectral hardness consistent with large changes in the ab…
X-Ray Emission from Isolated Hot White Dwarfs
Heise, J.
Hot white dwarfs are objects that copiously emit in the Extreme Ultraviolet and soft X-ray range. They are the brightest sources seen in the Low Energy Telescope of EXOSAT, with countrates up to 25 cnts/s. in contrast to their optical and UV spectrum the total flux and spectral distribution at soft X-ray energies are highly sensitive to the effect…
PHL 227 : the discovery of a new nova-like object.
Heber, U.; Koester, D.; Hunger, K.
The southern (13.5-mag) subdwarf candidate PHL 227 is found to be a nova-like object (UX UMa star). The line spectrum, both at visual and UV wavelengths, is strikingly similar to that of the well known UX UMa star V3885 Sgr. PHL 227 lies in the sky region of the Palomar Green survey. In this survey only two UX UMa stars (brighter than B = 16.2) so…
EXOSAT observations of the X-ray pulsar 4U1145-619
Warwick, R. S.; Watson, M. G.; Willingale, R.
EXOSAT observations of the X-ray pulsar 4U1145-619 during June and July 1983 and July 1984 confirm that this source shows a regular 187 day outburst cycle in X-rays. The results from pulse timing and X-ray spectroscopy are discussed in terms of a model for 4U1145-619 involving an eccentric binary system in which there is variable accretion from th…