Search Publications
Accretion disk in the high-redshift quasar HS 1700+6416.
Siemiginowska, A.; Dobrzycki, A.
We apply the standard accretion disk model to reproduce the EUV spectrum of the high-redshift (z = 2.72) quasar HS 1700+6416. We find a satisfactory fit to the observed spectrum. The contribution of the accretion disk to the continuum emission in the soft X-ray spectral region may be significant.
The nature of the hot subdwarf SB 744.
Unglaub, K.; Bues, I.
Various spectra in the visual wavelength range, one low-resolution ultraviolet spectrum, and color measurements in the red region have been taken to clarify the nature of the hot subdwarf SB 744. The colors and weak metallic lines as well as a G-band (CH) in the visual spectra indicate the existence of a cool companion, whereas the hydrogen and he…
Spectro-imagery of small diameter galaxies. I. Markarian 600 = MCG 1-08-008.
Figon, P.; Vanderriest, C.; Augarde, R. +1 more
The blue dwarf irregular galaxy Markarian 600 was observed by classical (slit) spectrography as well as bidimensional (fibre optics) spectrography. This object is found to be metal-deficient (about 1/8 solar) with an underabundant young stellar content. Two knots of gas ionized by hot stars (T_eff_ ~/- 50 000 K) are imbedded in a faint red envelop…
Search for chromospheric MgII emission in Ap-type stars.
Seggewiss, W.
Observations of the Mg II h and k line resonance doublet in the spectra of 10 of the latest Ap-type stars show no sign of emission cores in the broad absorption lines. Thus, the Mg II lines give no evidence for chromospheric activity in peculiar A-type stars; the present observations sharpen the boarder between active and non-active stars. This fa…
The ultraviolet spectrum of the hydrogen-poor binary HD 30353.
Hack, M.; Parthasarathy, M.; Tektunali, G.
An analysis is made of the high- and low-resolution UV spectra of the hydrogen-poor star HD 30353. The stellar wind profiles of the resonance lines of N V, C V, and Si IV are found to be similar to those observed in Upsilon Sgr. However, HD 30353 shows shortward-shifted profiles also in the ground-level lines of Fe II, in the subordinate multiplet…
LTE analysis of the far-ultraviolet variations of 21 Comae.
Monier, R.; Megessier, C.
The far-ultraviolet variations of the cool Ap star 21 Com in the spectral region 1450 - 1510 A are studied by using synthetic spectra. The integrated flux of the star is calculated, and the effective temperature of the star is derived and found to be lower than previous estimates. The computation of synthetic spectra indicates that the flux at the…