Search Publications
Hubble Space Telescope observations of the nucleus and inner coma of comet 19P/1904 Y2 (Borrelly)
Weaver, Harold A.; Toth, Imre; Lamy, Philippe L.
The nucleus of comet 19P/Borrelly was detected using the Planetary Camera (WFPC2) of the Hubble Space Telescope (HST). During the time of our observations, the comet was 0.62 AU from the Earth, 1.40 AU from the Sun, and had a solar phase angle of 38°. The high spatial resolution of the HST images allowed us to discriminate clearly between the sign…
Mid-IR emission of galaxies in the Virgo cluster. II. Integrated properties
Boulanger, F.; Sauvage, M.; Boselli, A. +7 more
We analyse the integrated properties of the Mid-IR emission of a complete, optically selected sample of galaxies in the Virgo cluster observed with the ISOCAM instrument on board the ISO satellite. The ISOCAM data allows us to construct the luminosity distribution at 6.75 and 15 mu m of galaxies for different morphological classes. These data are …
The distribution of nearby stars in phase space mapped by HIPPARCOS. II. Inhomogeneities among A-F type stars
Creze, M.; Chereul, E.; Bienayme, O.
A volume limited and absolute magnitude limited sample of A-F type dwarfs within 125 parsecs of the Sun is searched for inhomogeneities in the density-velocity space, expecting signatures of the cluster evaporation, phase mixing and possible disc heating mechanisms. A 3-D wavelet analysis is used to extract inhomogeneities, both in the density and…
Evidence for a signature of the galactic bar in the solar neighbourhood
Udry, S.; Raboud, D.; Grenon, M. +2 more
Using available kinematical data for a subsample of NLTT stars from the HIPPARCOS mission we confirm the existence of a previously reported local anomaly in the (u,v) plane: the mean motion /line{u} for old disc stars, with v < -30 km s(-1) , is largely positive (+19 +/- 9 km s(-1) w.r.t. the Galactic Center). With the use of the newest global …
Properties of the quiet Sun EUV network
Keenan, F. P.; Phillips, K. J. H.; Gallagher, P. T. +1 more
Observations of the quiet Sun network in a small region at Sun centre taken with the Coronal Diagnostic Spectrometer (CDS) on board SOHO are reported for EUV lines with T_e between ~ 10(4) and 10(6) K. The changing structure of the network in the upper chromosphere, transition region, up to the corona was examined using intensity distributions whi…
Discovery of CO_2 emission in AGB stars with the 13mu M dust feature
Waters, L. B. F. M.; Feuchtgruber, H.; Justtanont, K. +4 more
We have detected strong emission lines at 13.48, 13.87, 14.97, 15.40 and 16.28mu m in the ISO/SWS spectra of O-rich AGB stars. These lines are only found in the spectra of Miras and semi-regular variables when they also show the 13mu m dust emission feature. The lines appear just resolved in the high-resolution (AOT06, resolution ~ 1500) SWS spect…
The beta Pictoris circumstellar disk. XXIV. Clues to the origin of the stable gas
Deleuil, M.; Spyromilio, J.; Feldman, P. D. +11 more
GHRS high resolution spectra of {beta \:Pictoris} were obtained to study the stable gas around this star. Several elements are detected and their abundances measured. Upper limits to the abundances of others are also measured. The data permit improved chemical analysis of the stable gas around {beta \:Pictoris}, and yield new and more accurate est…
Oscillation mode identifications and models for the delta Scuti star FG Virginis
Kjeldsen, H.; Bruntt, H.; Frandsen, S. +4 more
We present new spectroscopic and photometric time series observations of the delta Scuti star FG Vir. We detect the oscillations via changes in the equivalent widths of hydrogen and metal absorption lines. From the ratios between spectroscopic and photometric amplitudes, we assign l values to the eight strongest oscillation modes. In particular, w…
Wolf-Rayet stars and O-star runaways with HIPPARCOS. II. Photometry
van der Hucht, K. A.; Moffat, A. F. J.; van den Heuvel, E. P. J. +9 more
Abundant {HIPPARCOS photometry over 3 years of 141 O and Wolf-Rayet stars, including 8 massive X-ray binaries, provides a magnificent variety of light curves at the sigma ~ 1-5% level. Among the most interesting results, we mention: optical outbursts in HD 102567 (MXRB), coinciding with periastron passages; drastic changes in the light curve shape…
Detection of spatial variations in the (D/H) ratio in the local interstellar medium
Vidal-Madjar, Alfred; Koester, Detlev; Ferlet, Roger +6 more
We present high resolution (Delta lambda = 3.7 km.s^{-1}) HST-GHRS observations of the DA white dwarf G191-B2B, and derive the interstellar D/H ratio on the line of sight. We have observed and analysed simultaneously the interstellar lines of Hi, D i, N i, O i, Si ii and Si iii. We detect three absorbing clouds, and derive a total Hi\ column densi…