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An unprecedented UV/optical flare in TV Columbae.
Szkody, P.; Mateo, M.
A surprising, 2 mag, short time scale (hr) outburst of TV Col (2A 0526-328) was observed simultaneously at IUE and optical wavelengths in 1982 November. During this 'flare', the IUE emission lines of N v 1240, C IV 1550, and He II 1640, intensified by more than an order of magnitude and developed P Cygni profiles, indicating mass loss. Continuum f…
Evidence for 4.4 hour periodic dips in the X-ray flux from 4U 1755-33.
Parmar, A. N.; White, N. E.; Kahn, S. M. +3 more
The paper reports the discovery by the EXOSAT Observatory of three equally spaced dips in the flux from 4U 1755 - 33 that suggest the binary period of this system to be 4.4 hr. The duration of each dip is of order 30 minutes with considerable variability within each event on time scales between 30 and 600 s. The variations are spectrally independe…
The unique planetary nebula NGC 2818.
Dufour, R. J.
The planetary nebula NGC 2818, or PK 261 + 8 deg 1, is of special interest due to its apparent association with a Population I open cluster (of the same designation). The results of new observations of the nebula are presented, including interference-filter imagery, photoelectric photometry, and ground-based and IUE spectroscopy. Analysis of its c…
Spectrophotometry of extreme helium stars : ultraviolet fluxes and effective temperatures.
Heber, U.; Drilling, J. S.; Lynas-Gray, A. E. +1 more
Ultraviolet flux distributions are presented for the extremely helium rich stars BD +10 deg 2179, HD 124448, LSS 3378, BD -9 deg 4395, LSE 78, HD 160641, LSIV -1 deg 2, BD 1 deg 3438, HD 168476, MV Sgr, LS IV-14 deg 109 (CD -35 deg 11760), LSII +33 deg 5 and BD +1 deg 4381 (LSIV +2 deg 13) obtained with the International Ultraviolet Explorer (IUE)…
How to find galaxies at high redshift.
Hartmann, L. W.; Huchra, J. P.; Geller, M. J.
The UV and optical spectra presented for the blue star-forming galaxies Mrk 357, Mrk 496, and Mrk 26 have sufficiently large redshifts to make Lyman-alpha observations possible. Weak Lyman-alpha emission is observed in Mrk 357 and Mrk 469, with a flux value comparable to that of H-beta, and no detectable Lyman-alpha emission is detected in the cas…
Two new extremely hot pulsating white dwarfs.
Green, R. F.; Bond, H. E.; Grauer, A. D. +1 more
High speed photometry of the extremely hot, nearly degenerate stars PG 1707 + 427 and PG 2131 + 066 reveals that they are low-amplitude pulsating variables. Power spectral analysis shows both to be multiperiodic, with dominant periods of 7.5 and 6.4-6.9 minutes, respectively. Together with the known pulsators PG 1159 - 035 and the central star of …
IUE observations of longitudinal and temporal variations in the Jovian auroral emission
Skinner, T. E.; Durrance, S. T.; Feldman, P. D. +1 more
The IUE's short wavelength spectrograph has been used to monitor the auroral emissions from Jupiter's northern hemisphere, yielding eight observations between January 1981 and January 1982 of H I Lyman-alpha and the H2 Lyman and Werner bands. Attention is given to an apparent periodic emission flux fluctuation, through detailed modeling of the emi…
Stellar chromospheres and coronae in the Ursa Major cluster stars.
Golub, L.; Linsky, J. L.; Simon, T. +2 more
IUE spectra of 18 proposed members of the Ursa Major Cluster and Einstein X-ray images of 11 of these stars are discussed. Thirteen stars, six in the nucleus and seven in the extended comoving stream, are probably true members of the UMa Cluster in that their bright ultraviolet and X-ray surface fluxes indicate youth. Four stars, one in the nucleu…
The detection of X-rays from nova MUSCAE 1983 with the EXOSAT satellite.
Beuermann, K.; Krautter, J.; Oegelman, H.
Nova Muscae 1983, a fast classical nova, was discovered on January 18, 1983, by Liller (1983). The present investigation is concerned with a study of this star on the basis of X-ray observations which have been conducted with the low- and medium-energy detectors of the Exosat satellite on April 20, 1984. The measured data are combined with other m…
PG 1012-029 : a high-excitation eclipsing cataclysmic variable.
Green, R. F.; Liebert, J.; Penning, W. R. +2 more
The paper presents a photometric and spectrophotometric analysis of a new eclipsing cataclysmic variable, PG 1012-029, with an orbital period of 3 hr 14 minutes 18.7 s. The eclipse depth reaches 1.9 mag, is rounded at minimum, and shows a prolonged egress 'shoulder', as found for UX UMa and some other eclipsing systems. The spectrum shows strong h…