Search Publications

ISO observations of four active galaxies

Rigopoulou, D.; Dennefeld, M.; Spoon, H. W. W. +1 more

We present ISO PHOT-S spectra of four galaxies known or suspected to host a central AGN. Two of them are selected, among several others, from the initial Iras/Rosat sample of Boller et al. (\cite{Boller92}) because of their substantial X-ray emission, while no obvious Seyfert features was present in their optical spectra: IRAS 14201+2956 and IRAS …

In-flight performance of the IBIS calibration unit

Malaguti, G.; Bird, A. J.; Ubertini, P. +3 more

We describe the in-flight performance of the on-board calibration unit for the IBIS telescope on INTEGRAL. Both intrinsic performance and the quality of the calibration signals provided to the IBIS detector planes are discussed. The calibration unit intrinsic performance is assessed based on the diagnostic information in IBIS housekeeping. The flu…

A comparison between the CaII(k₃), H_alpha , SOHO/MDI and radio-enhanced temperature regions of the Sun

Pohjolainen, S.; Valtaoja, E.; Riehokainen, A.

We present a comparison of the enhanced temperature regions (ETRs) in the radio emission of the Sun with other manifestations of solar activity over 5 days. The radio observations at 87 GHz were observed with the Metsähovi Radio Telescope (Finland). We superposed the intensity contours of the full-disk radio maps on the Meudon spectroheliograph Ca…

Improving the spatial resolution of XMM-Newton EPIC images by direct demodulation technique}

Feng, Hua; Zhang, S. N.; Lu, F. J. +2 more

We have applied the direct demodulation technique to XMM-Newton EPIC images to achieve a higher spatial resolution; the restored images are compared with Chandra images. With the improved images we can extract spectra of fine structures in XMM-Newton data.

On the XMM-Newton spectra of soft X-ray selected QSOs

Georgantopoulos, I.; Barcons, X.; Akylas, A.

We study the XMM-Newton spectra of a sample of 32 soft X-ray selected QSOs. Our goal is to check, using the spectra of moderate redshift (z ~ 1.5), faint (f_0.2-8 keV>5x 10^-15 erg cm^-2 s^-1) broad-line QSOs, previous claims for either significant intrinsic absorption or spectral hardening at high energi…

A search for O VI in the winds of B-type stars

Massa, D.; Fullerton, A. W.; Lehner, N. +1 more

We have conducted a survey of FUSE spectra of 235 Galactic B-type stars in order to determine the boundaries in the H-R diagram for the production of the superion {O Vi} in their winds. By comparing the locations and morphology of otherwise unidentified absorption features in the vicinity of the {O Vi} resonance doublet with the bona fide wind pro…

High resolution spectroscopy of HD 207538 from Far-UV (FUSE) to Visible (SARG-TNG). A global picture of the stellar and interstellar features modeled

Leone, F.; André, M. K.; Sonnentrucker, P. +1 more

We present a detailed study of the suspected Chemically Peculiar star HD 207538 based on high resolution spectroscopy in the far Ultraviolet (1000-3350 Å) and visible (4600-7000 Å) ranges. The stellar abundance synthesis analysis was performed by using Kurucz's codes ATLAS9 and SYNTHE to compute the atmospheric model and the synthetic spectrum res…

Close pairs of quasars with different redshifts: New observations and results

Surdej, J.; Iovino, A.; Lee, D. W. +4 more

Burbidge et al. (\cite {burbidge}) argue that the observed number of quasar pairs with small angular separations and different redshifts (typically Delta theta <= 5 arcsec and Delta z > 0.1 ) is not compatible with a random distribution of quasars over the sky. After a brief review of all known quasar pairs with different redshifts, we show …

A study of the Mg II 2796.34 Å emission line in late-type normal and RS CVn stars

Badiali, M.; Cardini, D.; Altamore, A. +2 more

We carry out an analysis of the Mg II 2796.34 Å emission line in RS CVn stars and make a comparison with the normal stars studied in a previous paper (Paper I). The sample of RS CVn stars consists of 34 objects with known HIPPARCOS parallaxes and observed at high resolution with IUE. We confirm that RS CVn stars tend to possess wider Mg II lines t…

IBIS performances during the Galactic Plane Scan. I. The Cygnus region

Rodriguez, J.; Foschini, L.; Capitanio, F. +8 more

The Plane of our Galaxy is regularly observed by the INTEGRAL satellite by means of scheduled scans. We present here results from the IBIS/ISGRI instrument using data from the first two Galactic Plane Scans performed at the end of the Performance Verification phase, while INTEGRAL was pointed towards the Cygnus region.

Considering the predict…