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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)…
Diffuse LY alpha emission around NGC 1275.
Fabian, A. C.; Nulsen, P. E. J.; Arnaud, K. A.
The authors report on short wavelength ultraviolet observations (1200 - 1900 Å) of NGC 1275 taken with the International Ultraviolet Explorer satellite. Diffuse Lyα radiation was discovered which is identified with the optical filaments surrounding the galaxy. The lack of a detected ultraviolet stellar continuum limits the number of massive young …
The pulsating extreme helium star BD +13 3224. II. Ultraviolet fluxesand effective temperature variations.
Heber, U.; Lynas-Gray, A. E.; Hill, P. W. +1 more
BD + 13 deg 3224 (V652 Her) is characterized on the basis of low-resolution spectra obtained with the short-wavelength prime camera of the IUE on July 5, 1980, and optical spectra obtained at integration time 200 s with the 3.9-m Anglo-Australian Telescope on May 24 and 25, 1980. The results are presented in tables and graphs and discussed. Static…
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 …
The early-type strong emission-line supergiants of the Magellanic Clouds : a spectroscopic zoology.
Shore, S. N.; Sanduleak, N.
The results of a spectroscopic survey of 21 early-type extreme emission line supergiants of the Large and Small Magellanic Clouds using IUE and optical spectra are presented. The combined observations are discussed and the literature on each star in the sample is summarized. The classification procedures and the methods by which effective temperat…
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…
The Be star phenomena. II - Spectral formation and structure of envelopes
Hirata, R.; Kogure, T.
The mechanisms of formation of the continuum and line spectra of Be stars and the morphology of their cool and hot envelopes are discussed in a review of recent theoretical and observational studies, supplementing the statistical evaluation of Kogure and Hirata (1982). Topics examined include the rapid rotation of Be stars, envelope dynamics, radi…
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…