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Ultraviolet spectroscopic investigation of HU Aqr and AN UMa with the data from HST and IUE
Sanad, M. R.
We present ultraviolet spectroscopic study of two polar systems, HU Aqr and AN UMa, observed with the Hubble Space Telescope's Space Telescope Imaging Spectrograph (STIS) and Faint Object Spectrograph (FOS) and with the International Ultraviolet Explorer (IUE) during the period 1979--2003, to diagnose the ultraviolet fluxes of C IV 1550 Å and He I…
A Composite Light Curve Model of the Symbiotic Nova PU Vul (1979)
Mikołajewska, J.; Kato, M.; Hachisu, I.
PU Vul (1979) is a symbiotic nova that shows a long-lasting flat optical peak followed by a slow decline. We made a quasi-evolution model for outbursts on a 0.6 M⊙ white dwarf consisting of a series of static solutions with optically-thin winds. Our theoretical models reproduce well the observed visual/UV light curves as well as the new…
Multiwavelength SED as a Tool in Understanding Outbursts of Symbiotic Binaries
Skopal, A.
Symbiotic binaries consist of a few sources of radiation contributing to spectral energy distribution (SED) from hard X-rays to radio wavelengths. To identify the basic physical processes forming the observed spectrum, we have to disentangle the composite SED into its individual components of radiation, i.e., to determine their physical parameters…
A Statistical Study of the si IV Resonance Line Parameters in 19 Be Stars
Antoniou, A.; Stathopoulos, D.; Danezis, E. +2 more
Using the GR model, we analyze the ultraviolet Si IV resonance lines in the spectra of 19 Be stars of different spectral subtypes, in order to detect the presence of absorption components and to analyze their characteristics. From this analysis we can calculate the values of a group of physical parameters, such as the apparent rotational and radia…
Studying the UV mg II Resonance Lines in 20 Be Stars
Antoniou, A.; Stathopoulos, D.; Danezis, E. +1 more
Using the GR model, we analyze the UV Mg II resonance lines in the spectra of 20 Be stars of different spectral subtypes, in order to detect the presence of satellite or discrete absorption components. The values of some physical parameters -- rotational, radial and random velocities, as well as the FWHM and the absorbed energy, as a function of t…
Helium, Carbon and Silicon Abundances in the HW VIR Eclipsing Binary Subdwarf-B Primary
Lynas-Gray, A. E.; Mortimore, A. N.
Light curve solutions show HW Vir and PG 1336-018 to be remarkably similar eclipsing binaries. The subdwarf-B (sdB) primary of PG 1336-018 is a pulsator but pulsation is not detected in the sdB primary of HW Vir. Ultraviolet spectra were used to obtain carbon and silicon abundances in the sdB primary of HW Vir; in due course these should be compar…
The Collective UV Behavior of Old Novae
Selvelli, P.
The UV spectral properties of 18 old-novae observed with IUE are examined. The de-reddened continuum energy distribution is well described by either a power-law distribution Fλ ∼λ -α with α in the range 0.3--2.5 or by a single black-body distribution with T in the range 15 000--38 000 K. The new values of EB-V ha…
An IUE Archival Study of the White Dwarf Temperature Variation in the Dwarf Nova WZ Sagittae
Sion, E. M.; Cheng, F. H.; Slevinsky, R. J. +2 more
The IUE archive offers a series of far UV spectra of ultra-short period dwarf nova WZ Sge over a long time baseline and hence the opportunity to monitor the ongoing accretion, the cooling of the white dwarf and temporal variations in the line spectra. We have carried out a quantitative analysis of these spectra including model atmosphere simulatio…
Stellar Wind Variability from IUE Spectra of Epsilon Orionis
Sapar, L.; Sapar, A.
21 IUE spectra of epsilon Ori (HD 37128), B0 supergiant, were studied to analyze variations in the profiles of the resonance lines of N V, C IV, Si IV and Si III. The largest variations in the profiles of resonance doublets of N V, C IV and Si IV are found in blue wings of the lines at velocities from --1500 to --2000 km/s, reaching in some spectr…
The Secondary Star in AM CVn
Solheim, J. -E.; Nymark, T. K.
The spectrum of AM CVn shows no definite sign of a secondary star, but through black body calculations of the spectra of the primary, disc and secondary objects, we find that if a one-temperature model for the secondary is assumed, a secondary which is cooler than 5000 K may be present without being seen in the spectrum. There is some excess flux …