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Time variability in the X-ray emission of dM stars observed by EXOSAT.
Schmitt, J. H. M. M.; Pasquini, L.; Collura, A.
The authors studied the variability in the X-ray emission of 13 dMe stars observed with the LE+CMA onboard EXOSAT. The basic aim of this paper is to search for frequently occurring impulsive events with small energy releases in an effort to find out whether the "quiescent" X-ray emission from dM stars is really quiescent. The authors do not find, …
EXOSAT Observations of the Supernova Remnant G109.1-1.0 and the X-Ray Pulsar 1E 2259+586
van der Klis, M.; Robba, N. R.; Smith, A. +1 more
The authors report on the EXOSAT observation of the supernova remnant (SNR) G109.1-1.0+1E 2259+586 system. The spatial distribution of the X-ray emission as derived from the low-energy (<2 keV) data is very similar to that obtained from the Einstein Observatory. The various components of the source (SNR shell, pulsar, and jet) have different sp…
Interstellar Absorption Lines in High-Resolution IUE Spectra of Cataclysmic Variables
Raymond, John C.; Mauche, Christopher W.; Cordova, France A.
High-resolution ultraviolet spectra of five cataclysmic variables obtained with the IUE are used to investigate the character of the interstellar medium in the vicinity of the sun. These spectra reveal narrow absorption features of neutral and singly ionized interstellar species, and, in SS Cyg, narrow velocity-shifted absorption features of C IV,…
Observational evidence for mass loss from classical cepheids.
Deasy, H. P.
This paper examines the evidence for mass loss from classical Cepheid variables in the light of recent observational studies of infrared and ultraviolet emission from these objects. Mass-loss rates derived for several stars range between 10-10M_sun;yr-1 and 10-6M_sun;yr-1. The lower end of this range pro…
The Carbon Chemistry in Interstellar Clouds toward Moderately Reddened Stars
Lambert, D. L.; Federman, S. R.
New data for C2 toward X Per, HD 206267, HD 207198, and Gamma Cep, for CH and CN toward X Per, and for CO toward HD 207198 have been obtained. The column densities of CH, C2, CN, and CO toward the stars in the Cepheus OB2 association are similar to reddened directions in Perseus and in Ophiuchus, indicating a similarity in physical conditions for …
Rotational modulation and flares on RS CVn and BY DRA stars. IX. IUE spectroscopy and photometry of II Peg and V711 Tau during February 1983.
Linsky, J. L.; Catalano, S.; Rodono, M. +11 more
Evidence is presented for spots, plages, and flares on the noneclipsing RS CVn system II Peg and V 711 Tau. The large spot originally found on II Peg in 1981.8 could still be identified in 1983. Two spectroscopic flares of II Peg were detected. For the larger flare the fluxes in the strongest transition-region lines reached about six times their q…
Improved Bow Shock Models for Herbig-Haro Objects: Application to HH 2A
Hartigan, Patrick; Raymond, John C.; Hartmann, Lee
An improved version of the bow shock theory previously applied to Herbig-Haro objects is presented. The modifications provide a more accurate calculation of the ionization state of material entering the bow shock. The revised preionization does not drastically affect the emission-line predictions for a 200 km/s bow shock model, though the effects …
IUE low resolution observations of the symbiotic star CH Cygni in 1979-1986.
Hack, M.; Mikolajewska, J.; Selvelli, P. L.
Data from IUE observations of the semiregular variable CH Cyg are presented compiled in extensive tables and graphs and analyzed with reference to theoretical models. The UV/optical continuum emission is accounted for by combining a Kurucz (1979) low-gravity A-type model atmosphere at Te = 8500-9000 K with hydrogen bound-free + free-free emission …
The Ultraviolet Calibration of the Hubble Space Telescope. III. A Correction for the Change in Sensitivity of the LWR Camera on IUE
Grillmair, Carl J.; Bohlin, Ralph C.
The absolute photometric calibration of the Hubble Space Telescope (HST) in the UV will be based on low-dispersion spectra obtained by IUE. Therefore, these data must be corrected for the substantial changes observed in the sensitivities of the IUE SWP and LWR cameras. A previous paper specified the correction in 5 A bins for SWP through 1986.36. …
Galactic Interstellar Abundance Surveys with IUE. II. The Equivalent Widths and Column Densities
Shull, J. Michael; van Steenberg, Michael E.
This paper continues a survey of interstellar densities, abundances, and cloud structure in the Galaxy, using the International Ultraviolet Explorer (IUE) satellite. Equivalent widths of 18 ultraviolet resonance transitions are presented and column densities for Si II, Mn II, Fe II, S II, and Zn II toward 261 early-type stars are derived. These eq…