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IUE observations of HD 164615.
Rucinski, S. M.
It is seen that HD 164615 with its spectral type F2 IV-V and (B - V) = 0.34 mag must be an exception to the rule that stars earlier than about F7 V cannot develop large spots. Abt, Bollinger and Burke (1983) found a periodic modulation of its brightness by 0.05 magnitude which they interpreted as resulting from the rotation of dark spots across th…
EXOSAT Observations of M Dwarfs
Schmitt, J. H. M. M.; Sztajno, M.
We give a progress report of our EXOSAT observations of active M dwarfs. The possibilities of filter spectroscopy of coronal X-ray sources using the available CMA filters are discussed, and we confirm that M dwarfs are rather hot coronal sources with X-ray temperatures in excess of 107 K, a result previously obtained with the Einstein O…
The ultraviolet spectrum of the planetary nebula M 3-27.
Feibelman, W. A.
The planetary nebula M3-27 was observed in the low-dispersion mode of the IUE satellite in the region 1150 A-3200 A. A fairly strong continuum was seen to extend down to 1150 A, superposed with a relatively small number of emission lines. A high electron density is inferred from forbidden O III but regions of lower density also exist. The ultravio…
An Investigation Into the Nature of the 4.4-HOUR Periodic Source 4U1755-33
Parmar, A. N.; White, N. E.; Mason, K. O. +1 more
We present the results of a continuous 18 hour observation of 4U1755-33 made with the European Space Agency's EXOSAT Observatory. Four 50 min dips in X-ray intensity were observed equally spaced with a period of 4.4 hrs, confirming the periodicity first suggested in White et al. (1984). The dips are spectrally independent. We examine the propertie…
The outer layers of the beta Cephei stars BW VUL and sigma Sco.
Blomme, R.; Hensberge, H.
Mass loss rates for the Beta Cephei stars BW Vul and Sigma Sco have been derived from the C IV and Si IV resonance lines, which are formed in the outflowing layers. Assuming an ionization fraction log q(C IV) = -1.9, mass losses of 1.4 and 1.9 x 10 to the -9th solar mass/yr are predicted for BW Vul and Sigma Sco, respectively. In the case of BW Vu…
M 62 : an RR Lyrae-rich, UV-bright galactic globular cluster.
Tarenghi, M.; Caloi, V.; Castellani, V.
The central region of the globular cluster M62 was observed with IUE. The authors confirm that, in the UV, M62 is the brightest cluster observed up to now in the galaxy. This RR Lyrae-rich system is another example of an UV-bright cluster with a horizontal branch not confined to the blue. The interpretation of UV excesses from spiral nuclei and el…
EXOSAT observations of the Perseus cluster
Fabian, A. C.; Branduardi-Raymont, G.; Manzo, G. +3 more
EXOSAT CMA and GSPC observations of the Perseus Cluster of galaxies are reported. The soft X-ray image data confirm the earlier Einstein Observatory results in terms of the density distribution radially outward from NGC1275. We have used the GSPC spectral data at higher energies to study the strength of the X-ray continuum and of the Fe line emiss…
Detection of Iron Lines in the Persistent Emission of Some X-Ray Burst Sources Observed by EXOSAT
Hasinger, G.; Sztajno, M.; Truemper, J. +1 more
We have observed the X-ray burst sources 4U1728-33 and 4U1813-14 with the ME detectors aboard EXOSAT, and present here results of a spectral analysis of their persistent emissions. For both sources the data can be well fitted by a double blackbody continuum and a Gaussian emission line. The two spectral components can be interpreted in terms of a …
Studies of hot B subdwarfs. II. Energy distributions of three bright sdB/sdOB stars in the 950-5500 A range.
Veilleux, S.; Fontaine, G.; Wesemael, F. +2 more
Voyager ultraviolet spectrometer observations of the subdwarf B or OB stars HD 205805, UV 1758+36 and Feige 66 are presented. All three objects display the H I Layman series in absorption. These observations are combined with low dispersion IUE spectrophotometry and with Stromgren photometry to construct virtually complete energy distributions, wh…
IUE data analysis : radial velocities from line coincidence statistics.
Bord, D. J.; Davidson, J. P.
The authors have employed the method of wavelength coincidence statistics (WCS) to determine radial velocities from International Ultraviolet Explorer (IUE) satellite data for several chemically peculiar stars. By repeatedly carrying out the entire WCS procedure with a sequence of radial velocities, the authors demonstrate that significance-weight…