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A study of the dependence of MG II emission on the rotational periodsof main-sequence stars.
Hartmann, L.; Baliunas, S. L.; Duncan, D. K. +1 more
International Ultraviolet Explorer satellite measurements of the Mg II chromospheric emission from a sample of late-type dwarfs with known rotational periods are presented. The ratio of chromospheric to photospheric luminosity for the late-G and K type stars in this sample can be fitted within the probable errors by a single function of rotational…
Hot subdwarfs in detached binary systems and thick-disk cataclysmic variables from the Palomar-Green survey.
Green, R. F.; Liebert, J.; Ferguson, D. H.
A total of 19 stars from the Palomar Green (PG) survey which were found to show composite spectra, generally with a hot subdwarf primary and a cool main-sequence secondary star, are discussed. The primary components have Teff values between 27,000 and 38,000 K (Mv = +5 to +7) and log g = about 6.5, while the secondaries generally show spectral typ…
Radial velocity studies of cataclysmic binaries. II. The ultrashort period dwarf nova T Leonis.
Szkody, P.; Shafter, A. W.
Spectroscopic and photometric observations of T Leo which reveal the object to be an ultrashort period dwarf nova are presented. In particular, the analysis indicates that T Leo has an orbital period of 84.69936 (plus or minus 0.00068) minutes, which is the third shortest orbital period of any known cataclysmic variable and the shortest known for …
The chromosphere and corona of T Tauri.
Jordan, C.; Brown, A.; de M. Ferraz, M. C.
Observations of the ultraviolet spectrum of the pre-main-sequence star T Tauri have been made using the International Ultraviolet Explorer (IUE) satellite. The fluxes of the emission lines are used to make models of the temperature and density structure of the chromosphere and transition region to the corona. Several models are discussed to cover …
High-resolution IUE observations of interstellar absorption lines in the VELA supernova remnant.
Jenkins, E. B.; Wallerstein, G.; Silk, J.
Ultraviolet spectra of 45 stars in the vicinity of the Vela supernova remnant were recorded by the short-wavelength echelle spectrograph aboard the International Ultraviolet Explorer (IUE). Over one-third of the stars show interstellar absorption lines at large radial velocities (greater than 60 km/s). The mapping of these high-velocity components…
Ultraviolet spectral morphology of the O stars. II. The main sequence.
Walborn, N. R.; Panek, R. J.
A survey of the 1200-1900 A region in 49 spectra of types O3-B1 V, based upon IUE high-resolution data, is presented. Standard sequences of prominent spectral features are illustrated, and UV classification criteria are introduced. For the majority of the stars, there is an excellent correlation between the behavior of the UV features, both stella…
Ultraviolet spectroscopy of the dwarf nova U Geminorum.
Holm, A. V.; Panek, R. J.
Spectrophotometry at 6 A resolution is presented for the dwarf nova U Gem over the range 1150-3200 A, with simultaneous visual broad-band photometry, from observations with the International Ultraviolet Explorer. The observations were made at 1, 5, 11, 26, 71, and 108 days after the start of an outburst. Near the outburst maximum the spectra show …
Photospheric soft X-ray emission from hot DA white dwarfs.
Raymond, J. C.; Wesemael, F.; Kahn, S. M. +3 more
Soft X-radiation (≡150 eV) from four hot DA white dwarfs (EG 187, Gr 288, Gr 289, and LB 1663) has been detected with the imaging proportional counter of the Einstein Observatory. The observed pulse-height spectra are very soft and suggest that the emission arises from the hot photosphere with implied effective temperatures in the range 30,000 - 6…
Effective temperatures and luminosities of very hot O type subdwarfs.
Drilling, J. S.; Schonberner, D.
Twelve very hot O-type subdwarfs were observed with the IUE-satellite in the low dispersion mode. Temperatures were derived from the slopes of the UV continua and distances were estimated from the color excesses. Most of them are hotter than 60,000 K, i.e., they are the hottest known subdwarfs. From their spectral appearance and location in a H.R.…
International Ultraviolet Explorer observations of stars in 30 Doradus : extinction and stellar continua.
Savage, B. D.; Fitzpatrick, E. L.
A study of ultraviolet interstellar extinction in and near the core of the 30 Doradus nebula is presented. The pair method is used to determine the shape of the ultraviolet extinction curve, and reddened stars from within 80 pc of the core and unreddened stars from a variety of locations in the Large Magellanic Cloud (LMC) are considered. All star…