[en] Preliminary results are presented of a program to study the optical and infrared continuum emission of quiescent QSOs using simultaneous UBVRIJHK photometry. The amplitude of variability in six of the seven sources discussed is greatest in the blue and ultraviolet and decreases toward longer wavelengths. Only 3C 273 exhibits variability at all wavelengths observed, changing by a similar amount in each spectral band.All of the other QSOs were nonvarying at 2.2 microns, despite variations in the visible and ultraviolet. This variability behavior and the optical-infrared spectral energy distribution in each object except 3C 273 strongly suggest that the infrared and variable optical continuum emission arise from distinct sources within the QSOs. Several possible models of the origin of the continua are examined. 29 references

[en] The spectral characteristics of the continuum and of the lines (in absorption or in emission) in the spectra of quasars and active nuclei are reviewed. Then, the main problems concerning their interpretation are summarized

[en] Z And is considered as the ''prototype'' of the symbiotic stars. Besides its symbiotic spectrum, the star is also known for its characteristic light curve (and for the related spectral variations). Since many theoretical speculations on Z And and similar objects have been based on the luminosity and spectral variations of this star, the authors critically analyse the observational data concerning it. (Auth.)

[en] Methods are presented for determining the effective temperatures, radii and bolometric corrections for B-type supergiants. Absorption lines from hydrogen and from other elements, the H alpha, Balmer progression, and evidence for outflow from the invisible spectrum of these supergiants are considered. Luminosity effects, outflow velocities, and variability in the UV spectrum at high resolution are examined as well as the infrared and radio spectra. Spectroscopic characteristics of the peculiar supergiant P Cyg and superluminous supergiants, X-ray binaries, the properties of the photosphere and mantle and mass loss are elaborated. A general model for the mantle of B stars is included and the properties of B type stars in the main sequence are compared with those of the B-type supergiants

[en] Volume A5 of the ''Uranium'' series of the Gmelin Handbook deals with the various types of absorption and emission spectra of uranium and its compounds, covering atomic, absorption, luminescence, X-ray, photoemission, infrared, NMR, ESR, and Moessbauer spectra. The several authors have given not only a critical compilation of the published material but also an up-to-date interpretation. (orig./GSCH)

[en] Nine spectra of the quasar 3C 273 have been obtained with the International Ultraviolet Explorer with the aim of combining them and obtaining a high signal-to-noise spectrum between 1100 and 3300 A. A detailed analysis is made of the emission line intensity ratios and of the continuous energy distribution. Evidence is found for a thermal contribution to the ultraviolet continuum. The ultraviolet spectrum of 3C 273, which was obtained, shows eight absorption lines at zero redshift due to the intervening material in our Galaxy. The C IV lambda 1550 absorption is much stronger in the spectrum of 3C 273 than in the spectra of halo stars. This is taken as evidence for the existence of a hot gaseous component in the outer regions of the halo of the Galaxy. (author)

[en] Mini-orange electron spectrometer (MOS), first developed by Van Klinken, has been used for in-beam internal conversion electron spectroscopic measurements by numerous workers. Due to the commendable energy resolution and flat efficiency curve of a cooled Si(Li) detector, the simultaneous recording of the electron spectrum over the large energy range is possible

[en] We present an analysis of the average spectral properties of 12,000 SDSS quasars as a function of accretion disc inclination, as measured from the equivalent width of the [OIII] 5007Å line. The use of this indicator on a large sample of quasars from the SDSS DR7 has proven the presence of orientation effects on the features of UV/optical spectra, confirming the presence of outflows in the NLR gas and that the geometry of the BLR is disc-like. Relying on the goodness of this indicator, we are now using it to investigate other bands/components of AGN. Specifically, the study of the UV/optical/IR SED of the same sample provides information on the obscuring “torus.” The SED shows a decrease of the IR fraction moving from face-on to edge-on sources, in agreement with models where the torus is co-axial with the accretion disc. Moreover, the fact we are able to observe the broad emission lines also in sources in an edge-on position, suggests that the torus is rather clumpy than smooth as in the Unified Model. The behavior of the SED as a function of EW[OIII] is in agreement with the predictions of the clumpy torus models as well.

[en] Long-exposure IUE observations are used here to determine the spatial distribution of the fluorescent H2 line emission in the low-excitation objects HH 43 and HH 47. In HH 43, the spatial distribution of the fluorescent H2 line emission has a width equal to or smaller than the width of the point-spread function of IUE, while both the short-wavelength UV continuum and the optical forbidden S II lines show distributions which are wider by more than a factor of two. In HH 47, the results are qualitatively analogous, but the differences between the fluorescent HH 23 emission distribution on the one hand, and the UV continuum and optical forbidden S II distribution on the other, are smaller. These distributions indicate that the appropriate conditions for the formation of fluorscent H2 lines are fulfilled only in rather narrow regions for these low-excitation objects. A continuous energy distribution in HH 43 and HH 47 is found which differs only slightly from that in the high-excitation objects HH 1 and HH 2. 48 refs

[en] We have carried out the synthesis of: - phenanthrene - its five monomethyl derivatives - three dimethyl derivatives - two trimethyl derivatives. We have then purified these products as well as a certain number of others obtained from various sources. We have been able to obtain in the majority of cases, a purity of 99.5 per cent or over, these figures being obtained by low voltage mass spectrometry. Finally we have recorded the infrared, ultraviolet, nuclear magnetic resonance and mass spectra of these products for which an atlas has been drawn up. (author)