Search Publications
The HIPPARCOS solar system objects catalogues
Lindegren, L.; Mignard, F.; Hestroffer, D. +3 more
Astrometric and photometric measurements of a number of solar system objects were performed by the Hipparcos satellite in both the Hipparcos main mission and the Tycho experiment. The results concern mainly asteroids but also the planetary satellites Europa, Ganymede, Callisto, Titan and Iapetus, and the major planets Uranus and Neptune. The speci…
The Chamaeleon infrared nebula revisited. Infrared imaging and spectroscopy of a young stellar object
Henning, Thomas; Feldt, Markus; Lagage, Pierre O. +3 more
We are presenting spectroscopic and imaging data on the Chamaeleon Infrared Nebula (Cha IRN). Imaging was done between 1 and 2.5mu m and at 10mu m. Spectra of the object were obtained in the 2.1mu m - 4.6mu m range by ground-based measurements as well as using ISOPHOT-S in the 2.5mu m - 11.6mu m range. By combining these data with a K-band speckle…
Lyalpha absorbers at z<= 1: HST-CFHT imaging and spectroscopy in the field of 3C 286
Bergeron, J.; Le Brun, V.
We present further observational results on our Lyalpha -only absorber identification project at low and intermediate redshifts. We combine CFHT/MOS imaging and spectroscopic observations of 25 galaxies in the field of the quasar 3C 286 (z_e = 0.849) with HST/FOS spectrum of the quasar between 1600 and 3000 Angstroms and HST/WFPC2 high spatial res…
ISOCAM images at 6.75mu M and 15mu m: the circumnuclear region of NGC4321 (M100)
Martinet, L.; Wozniak, H.; Friedli, D. +1 more
We present ISOCAM images (1.5\arcsec px(-1) ) in the LW2 (6.75mu m) and LW3 (15mu m) broad band filters of the circumnuclear starburst of NGC4321 (M100). A detailed comparison with the emission at other wavelengths (U, B, Hα , and CO) is also presented. The nature and intensity of the mid-infrared emission is shown to be remarkably different from …
Pulsation of the lambda Bootis stars HD 111786 and HD 142994
Paunzen, E.; Matthews, J. M.; Kuschnig, R. +3 more
The detection of possible nonradial pulsation modes among some lambda Bootis stars offers the prospect of using asteroseismology to determine their masses and ages, thereby testing competing theories for the origin of their chemical peculiarities. As a step toward this goal, we conducted multi-site photometric campaigns spanning two weeks each for…
Simultaneous intensive photometry and high resolution spectroscopy of delta Scuti stars. III. Mode identifications and physical calibrations in HD 2724
Mantegazza, L.; Bossi, M.; Nunez, N. S.
On the basis of our new simultaneous photometry and spectroscopy (885 \( uvby \) differential measurements in 11 nights and 154 spectrograms of the FeII\( \lambda \)4508 region in 5 nights), we can detect 12 probable periodicities in the variability pattern of this star, determining the frequencies of 7 without any ambiguity. Through a direct fit …
VCC 144: a star-bursting dwarf galaxy in the Virgo cluster
Brosch, N.; Almoznino, E.; Hoffman, G. Lyle
We describe results of a multi-spectral study of a blue compact dwarf galaxy in the Virgo Cluster. The object was observed with broad-band and Hα imaging, ultraviolet observations, and radio synthesis. Our data were combined with previously published optical observations, with HI single-beam observation and with far-infrared data, and were compare…
The solar transition region: a time-varying interface between the chromosphere and corona?
Doyle, J. G.; Keenan, F. P.; O'Shea, E.
Using joint observations taken with the CDS and SUMER instruments onboard SOHO, we re-examine the solar transition region in an attempt to determine whether it is de-coupled from the over-lying coronal region. Line ratios calculated from temporal series observations of O iv and Fe xiii spectral lines were converted to electron density, and hence e…
HST photometry of the stars near the center of PN NGC 650
Pottasch, S. R.; Koornneef, J.
Colours and magnitudes of the central star of NGC 650 and its two companions have been obtained from HST images. The spectral types of the companions, which have been deduced from the colours, suggest a probable distance to the companions of between 5 and 6 kpc. Using the spectral and photometric characteristics of the central star, which are very…
Pulsating and nonpulsating stars in Hyades observed by HIPPARCOS satellite
Antonello, E.; Pasinetti Fracassini, L. E.
A study of the stars in the instability strip of Hyades cluster has been performed taking into account the new estimate of the stellar parallaxes. For taking advantage of the improved accuracy of the distances and hence absolute magnitudes it is necessary to separate the photometric effects of close companions, which appear quite common in Hyades.…