1,721,050 research outputs found
The ultraviolet spectrum of KQ Puppis (BOSS 1985)
No full textThe high resolution spectrum of the VV Cep star KQ Pup observed with the IUE satellite during 1979 and 1980 is summarized. More than 600 lines have been identified between 1190 and 3228 A. Two main line systems are present, a broad absorption line system, which includes high ionization lines from N V, C IV, Si IV and Al III, and narrow P Cygni lines of neutral and singly ionized elements, mostly of Fe II. The Mg II resonance doublet is very prominent in emission with a sharp central absorption. The intensity of the absorption and emission components of the Fe II lines is different according to the excitation potential, transition strength and wavelength. Fe II emission lines with E.P. up to 13 eV are present. Several Fe II lines, were identified using the new Kurucz's computations
A comparative study of the ultraviolet spectrum of subdwarfs
No full textThe high and low resolution IUE spectra of four O subdwarfs (BD +75°325, BD +48°1777, BD +37°1977, BD +37°442) are analyzed. Line identification is given for the most abundant ions in the far ultraviolet. Fe V is by far the ion with the largest number of lines. Broad P Cygni profiles of the N V and C IV resonance doublets are observed in BD +37°442 and BD +37°1977, with terminal velocities of 2200 and 2300 km s-1 respectively. The N IV 1718 Å line presents an extended blue wing also arising in the winds of these stars. A low interstellar extinction (E(B-V) ≤ 0.05) is derived from the weakness of the 2200 Å i.s. band, and from the Lyα profile. Mean radial velocities are given for the photospheric and interstellar atomic species, and a high stellar velocity is found for the four stars, in agreement with the Population II nature of these objects
Objective Prism Study of the 1977 Spectrum of HDE 245770=A0535+26
No full textObjective prism plates of the optical"
"counter.part of the transient X-ray source A0535+"
"26 obtained during 1977 show strong H""' in emis sion and marked Balmer excess. Many other emis sion lines are probably present in the red-infra red.No large spectral time variation was foun
A Spectrophotometric Study of Ultraviolet and X-ray Sources with Objective Prism Plates
No full textSeveral objective prism spectra of objects known to have large ultraviolet or X-ray fluxes are discussed. A marked Balmer excess and H alpha emission are found in X Per(= 3U 0352 + 30) and in the similar Be star HD 200775. No Balmer discontinuity is detectable in HD 226868 (Cyg X-1) during the low X-ray states, in HZ 43 (MX 1313 + 29), and in the hot subluminous star BD + 37 deg 1977. Comparison with the far ultraviolet spectrum of this star (Carnochan et al., 1975) leads to the conclusion that the star is slightly reddened (EB-V = 0.15 plus or minus 0.05) with an optical-ultraviolet energy distribution close to a 100,000 K black-body
FOURIER-TRANSFORM SPECTROSCOPY AND NEAR-INFRARED VARIABILITY OF ETA-CARINAE
No full textWe present the first Fourier Transform Spectrograph near-IR spectrum (0.95-2.5 mu m) of eta Car observed at CFHT in January 1987 with a resolution of 40-100 km s(-1). We have identified lines of H I (Paschen, Brackett series), He I, Fe II, [Fe III, [N I] with complex structures. At the time of these observations eta Car was in a low excitation phase characterized by a general weakening of the hydrogen lines, and with the He I lambda 1082.9 nm line much weaker than in 1990-91
Exploring the nature of the symbiotic stars with high resolution spectroscopy.
No full textThere are some fundamental aspects of the "symbiotic phenomenon" which are poorly understood. Modern technology now allows to observe faint stars with efficient very high resolution spectrographs, such as the SARG mounted at TNG, which will be crucial for our understanding of the nature and evolutionary stage of symbiotic stars and related sytems. Of great importance will be the determination of luminosity, rotation, mass loss, chemical composition of the cool stellar components which is basic for settling the mass transfer in the system and tracing back its past history. High resolution observations are also needed to derive the velocity, temperature and abundance gradients in the nebula, and to unveil peculiar excitation processes
Wind accretion in KQ Puppis
No full textFrom a multiwavelength long term monitoring of KQ Pup, we derive a revised orbital period of 9500 days. The presence of an accreting stream is put in evidence by a large decrease of the FUV continuum due to Rayleigh scattering, and by the appearance of redshifted absorptions since Φ = 0.82
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