Search Publications
Time variation of SWS spectra of M-type Mira variables and its dust optical properties. I. Z Cyg
Onaka, T.; Yamamura, I.; de Jong, T.
The M-type Mira variable star, Z Cyg, was observed with the Short-Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO) 7 times at roughly 60 day intervals over one and a half period. The infrared spectrum (2.38-45.2 mu m) of Z Cyg shows prominent silicate emission bands at 10 mu m and 18 mu m and displays quite large variati…
XMM-Newton detection of Nova Muscae 1991 in quiescence
Kolb, U.; Casares, J.; Osborne, J. P. +7 more
The soft X-ray transient GU Mus has been detected by XMM-Newton in the quiescent state. The source is very faint, with a 0.5-10.0 keV unabsorbed flux of =~ 1.1 x 10-14 ergs cm-2 s-1. The spectra is well fit by an absorbed powerlaw with a photon index of alpha = 1.6 +/- 0.4, close to the value seen when the source w…
The stellar mass to light ratio in the isolated spiral NGC 4414
Braine, J.; Baudry, A.; Vallejo, O.
We present high resolution CO(1-0) interferometric observations and deep HST B-V-I images of the flocculent isolated Sc type spiral NGC 4414. The goal is to determine the stellar mass-to-light (M/L) ratio in a galactic disk. NGC 4414 is an ideal object for this kind of study, as it is an unperturbed object at high galactic latitude with very exten…
Solar cycle variation of the temperature structure within the cores of coronal streamers
Foley, C. R.; Culhane, J. L.; Patsourakos, S. +1 more
We use the Coronal Diagnostic Spectrometer onboard the Solar and Heliospheric Observatory (SOHO) to analyze conditions in coronal streamer structures observed close to solar minimum (1996 July 8) and near maximum (1999 August 5). We measured the intensities of emission lines from Fe IX-XV ions and found the most intense emission to be from Fe XI a…
Henry Draper catalogue identifications for Tycho-2 stars
Makarov, V. V.; Fabricius, C.; Wycoff, G. L. +1 more
We present identifications in the Tycho-2 Catalogue, for 99.8 per cent of the stars in the Henry Draper Catalogue and for 96 per cent of the Henry Draper Extensions. Based on observations made with the ESA Hipparcos astrometry satellite. The identifications are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.7…
HST observations rule out the association between Cir X-1 and SNR G321.9-0.3
Caraveo, P. A.; De Luca, A.; Mignani, R. P. +1 more
Cir X-1 is one of the most intriguing galactic X-ray sources. It is a ~16.6 days variable X/radio source, a type-I X-ray burster and a QPO emitter. In spite of an uncertain optical counterpart classification, all these properties identify the source as an LMXB. The morphology of the surrounding radio nebula has suggested an association with the ne…
The white dwarf cooling sequence in the old open cluster NGC 188
Andreuzzi, G.; Richer, H. B.; Limongi, M. +1 more
We develop the white dwarf luminosity function (LF) of the old open cluster NGC 188 in order to determine a lower limit to the age of the cluster by using the faint end of the cooling sequence. To produce an extensive sequence of the cooling white dwarfs we imaged four contiguous HST-WFPC2 fields in the center of the cluster in the F555W and F814W…
A morphological comparison between the central region in AGN and normal galaxies using HST data
Papadakis, I. E.; Xilouris, E. M.
We study the morphology of the central region of a sample of Active Galactic Nuclei (AGN) and a ``control'' sample of normal galaxies using archival observations of the WFPC2 instrument onboard the Hubble Space Telescope (HST). We use the ellipse fitting technique in order to get a good description of the inner ``smooth'' light distribution of the…
Precision and accuracy of the orbital parameters derived from 2D & 1D space observations of visual or astrometric binaries
Pourbaix, D.
Recent investigations (e.g. Han et al. \cite{Han-2001:a}) have shown that fitting the Hipparcos observations with an orbital model when the astrometric wobble caused by the companion is below the noise level can have rather unexpected consequences. With new astrometric missions coming out within the next ten years, it is worth investigating the or…
The signature of high-velocity gas in the spectra of NGC 4151
Prieto, M. A.; Contini, M.; Viegas, S. M.
The multiwavelength emission spectrum and associated velocity field of the Seyfert prototype NGC 4151 is modeled. Since the thirties NGC 4151 has been the subject of extensive modeling, nuclear photoionization being the basic approach considered by all authors. HST data has impressively revealed the existence of a large range of velocities (100-15…