Search Publications
Hubble constant from sosie galaxies and HIPPARCOS geometrical calibration
Paturel, G.; Bottinelli, L.; Gouguenheim, L. +5 more
New distances, larger than previous ones, have been obtained for M 31 and M 81 based on the geometrical zero-point of the Cepheid Period-luminosity relation provided by the HIPPARCOS satellite. By combining them with independent determinations we define reasonable ranges for the distances of these important calibrating galaxies. On this basis, we …
Number counts and redshift distribution of gravitational arclets as a probe of galaxy evolution
Pello, R.; Soucail, G.; Bezecourt, J.
We present a detailed model of the absolute number counts, color and redshift distributions of gravitational arclets observed in clusters of galaxies. The framework adopted for galaxy evolution is chosen to reproduce the observed number counts and redshift distribution of field galaxies. Then, a spectrophotometric evolutionary code is coupled with…
Are solar granules the only source of acoustic oscillations?
Foglizzo, T.
The excitation mechanism of low degree acoustic modes is investigated through the analysis of the stochastic time variations of their energy. The correlation between the energies of two different modes is interpreted as the signature of the occurrence rate of their excitation source. The different correlations determined by Foglizzo etal (1998) co…
On the new lambda Bootis-type spectroscopic binary systems HD 84948 and HD 171948
Handler, G.; Garrido, R.; Heiter, U. +4 more
We report the discovery of two new lambda Bootis-type spectroscopic binary systems (HD 84948 and HD 171948). High resolution spectra were analyzed in order to derive abundances as well as astrophysical quantities. It resulted in extreme (HD 171948) and moderate (HD 84948) underabundances of Na, Mg, Si, Ca, Sc, Ti, Cr and Fe with respect to the Sun…
An extremely red r(1/4) galaxy in the test image of the Hubble Deep Field South
Ferguson, H. C.; Walker, A. R.; Treu, T. +14 more
We report the serendipitous discovery of an extremely red object in the Hubble Deep Field South (HDFS) Test NICMOS (Near Infrared Camera and Multi Object Spectrograph) field of view. The object is resolved in the NICMOS image and has a light profile very well described by an r(1/4) law with effective radius re=0farcs 20+/-0.05 and H_AB=…
An estimation of the mass of asteroid 20-Massalia derived from the HIPPARCOS minor planets data
Bange, Jeff
The ESA astrometry satellite Hipparcos has observed a set of 48 minor planets between 1989 and 1993. A close encounter between 20-Massalia and 44-Nysa, both planets observed by Hipparcos, enabled us to obtain a value for the mass of 20-Massalia. Due to another close approach with the large asteroid 4-Vesta, the value we obtained (2.42 +/- 0.41 10(…
Boron in the very metal-poor star BD -13 3442
Deliyannis, Constantine P.; Primas, F.; Rebull, L. M. +5 more
The Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) has been used to observe the boron 2500 Angstroms region of BD -13 3442. At a metallicity of [Fe/H]=-3.00 this is the most metal-poor star ever observed for B. Nearly 26 hours of exposure time resulted in a detection. Spectrum synthesis using the latest Kurucz mode…
ASCA observation of the polar RX J1802.1+1804
Greiner, J.; Motch, C.; Ishida, M. +1 more
We present X-ray data of {RX J1802.1+1804} obtained by {ASCA}. Although it shows a clear orbital intensity modulation with an amplitude of nearly 100% below 0.5 keV in {ROSAT} data, the {ASCA} light curves are nearly flat except for a possible dip lasting about one-tenth of the orbital period. We discuss this within the model assumption of a strea…
Particle acceleration efficiency and MHD characteristics of CIR-related shocks
Mann, G.; Keppler, E.; Classen, H. -T.
During its southbound journey the Ulysses spacecraft crossed a series of corotating interaction regions (CIRs) building up due to the interaction of fast and slow solar wind streams. We analyse the forward and the reverse shocks marking off the 18 CIR encounters between July 1992 and December 1993. Our investigations look for a correlation between…
SVS 16: The most X-ray luminous young stellar object
Stanke, Thomas; Preibisch, Thomas; Neuhaeuser, Ralph
We present new infrared and X-ray data on the optically invisible infrared source SVS 16 in the NGC 1333 star forming region. We show that SVS 16 is a binary with a separation of 1''. The infrared spectrum displays photospheric atomic and CO absorption lines, and thus shows that SVS 16 is a highly obscured (A_V ~ 26 mag) low mass young stellar obj…