Search Publications
Structure of visible and dark matter components in spiral galaxies at redshifts z = 0.5{-0.9}
Tamm, A.; Tenjes, P.
We have constructed self-consistent light and mass distribution models for four disk galaxies at redshifts z=0.48, 0.58, 0.81 and 0.88, using the HST archive WFPC2 observations (HDF-S, MDS, Groth Strip survey) and rotation curves measured by Vogt et al. ([CITE]) and Rigopoulou et al. ([CITE]). The models consist of three components: a bulge, a dis…
Search for the elusive optical counterpart of PSR J0537-6910 with the HST Advanced Camera for Surveys
Pulone, L.; Mignani, R. P.; Iannicola, G. +3 more
We present the results of deep, high-resolution, multi-band optical observations of the field of the young (∼ 5000 yr) 16 ms X-ray pulsar PSR J0537-6910 performed with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope (HST). Although a few new potential counterparts have been detected within or close to the revised Chandra X-…
Orbital period variation in close binaries from radial velocity data and magnetic activity cycles. II. HR 1099
Lanza, A. F.; Frasca, A.
We studied orbital period changes in the non-eclipsing close binary HR 1099, one of the most bright members of the RS CVn class of magnetically active binary systems. Intermediate-resolution optical spectroscopy and IUE archive spectra were used to build radial-velocity curves yielding epochs of superior conjunction with an accuracy of 0.01 days. …
Low-energy absorption towards the ultra-compact X-ray binary 4U 1850-087 located in the globular cluster NGC 6712
Parmar, A. N.; Sidoli, L.; La Palombara, N. +1 more
We report the results of two XMM-Newton observations of the ultra-compact low-mass X-ray binary 4U 1850-087 located in the galactic globular cluster NGC 6712. A broad emission feature at 0.7 keV was detected in an earlier ASCA observation and explained as the result of an unusual Ne/O abundance ratio in the absorbing material local to the source. …
Bowen excitation of N III lines in symbiotic stars
Munari, U.; Wahlgren, G. M.; Johansson, S. +3 more
We present a semi-empirical equation for prediction of the strengths of those N III lines that are generated by the Bowen mechanism and observed in spectra of symbiotic stars. The equation assumes that the Bowen mechanism is the only source populating the 3d state in N III, and comparisons with observations of the 3s-3p and 3p-3d transitions serve…
Detection and analysis of a new INTEGRAL hard X-ray transient, IGR J17285-2922
Hill, A. B.; Capitanio, F.; Bird, A. J. +10 more
We present the transient nature of INTEGRAL source IGR J17285 2922, identified from a single period of activity during an IBIS/ISGRI Galactic Centre Deep Exposure in September 2003. The source has a maximum detection significance of 14σ in the 20 100 keV energy range and exhibits a flux of 6.5 mCrab before it moves out of the ISGRI field of view. …
FORS spectroscopy of galaxies in the Hubble Deep Field-South
Berta, S.; Aussel, H.; Franceschini, A. +2 more
We present low resolution multi-object spectroscopy of an I-band magnitude limited (IAB ≃ 23-23.5) sample of galaxies located in an area centered on the Hubble Deep Field-South (HDFS). The observations were obtained using the Focal Reducer/low dispersion Spectrograph (FORS) on the ESO Very Large Telescope. Thirty-two primary spectroscop…
AGN variability time scales and the discrete-event model
Paltani, S.; Courvoisier, T. J. -L.; Favre, P.
We analyse the ultraviolet variability time scales in a sample of 15 type 1 Active Galactic Nuclei (AGN) observed by IUE. Using a structure function analysis, we demonstrate the existence in most objects of a maximum variability time scale of the order of 0.02-1.00 year. We do not find any significant dependence of these maximum variability time s…
Abundances of planetary nebulae NGC 2022 , NGC 6818 and IC 4191
Pottasch, S. R.; Beintema, D. A.; Feibelman, W. A.
The ISO and IUE spectra of the elliptical nebulae
A serendipitous XMM-Newton observation of the intermediate polar WX Pyx
Schlegel, E. M.
We briefly describe a serendipitous observation of the little-studied intermediate polar WX Pyx using XMM-Newton. The X-ray spin period is 1557.3 s, confirming the optical period published in 1996. An orbital period of ~5.54 h is inferred from the separation of the spin-orbit sidelobe components. The soft and hard band spin-folded light curves are…