Search Publications
M2000: An astrometric catalog in the Bordeaux Carte du Ciel zone +11degr <= delta <= +18degr
Ducourant, C.; Soubiran, C.; Le Campion, J. -F. +11 more
During four years, systematic observations have been conducted in drift scan mode with the Bordeaux automated meridian circle in the declination band +11degr <= delta <= +18degr . The resulting astrometric catalog includes about 2.3x 106 stars down to the magnitude limit VM=16.3. Nearly all stars (96%) have been observe…
A Combined Hipparcos and Multichannel Astrometric Photometer Study of the Proposed Planetary System of ρ Coronae Borealis
Han, Inwoo; Gatewood, George; Black, David C.
Hipparcos and Multichannel Astrometric Photometer (MAP) observations of ρ Coronae Borealis independently display astrometric motion at the period of the proposed ``extrasolar planetary'' companion to the star. Individual least-squares fits to each astrometric data set yield independent estimates of the semimajor axis, inclination, and node angle t…
Orientation and Speed of the Parsec-Scale Jet in NGC 4261 (3C 270)
Jones, Dayton L.; Wehrle, Ann E.; Piner, B. Glenn
NGC 4261 (3C 270) is an elliptical galaxy containing a 300 pc-scale nuclear disk of gas and dust imaged by the Hubble Space Telescope (HST), around a central supermassive black hole. Previous VLBI observations of NGC 4261 revealed a gap in emission in the radio counterjet, presumably due to free-free absorption in the inner parsec of the accretion…
Local time asymmetry of the equatorial current sheet in Jupiter's magnetosphere
Cowley, S. W. H.; Bunce, E. J.
We provide a first systematic comparison of the radial fields associated with the equatorial current sheet in the Jovian magnetosphere which were observed during the flybys of the Pioneer-10 and -11, Voyager-1 and -2, and Ulysses spacecraft. These data span a ∼210° range of azimuths about the planet, from dusk via noon to the post-midnight sector.…
The Distance of the Large Magellanic Cloud Cluster NGC 1866
Walker, A. R.; Hill, V.; Castellani, V. +3 more
Hubble Space Telescope V, I photometry of stars in the Large Magellanic Cloud cluster NGC 1866 shows a well-defined cluster main sequence (MS) down to V=25 mag, with little contamination from field or foreground stars. We use the MS fitting procedure to link the distance of NGC 1866 to the Hipparcos determination of the distance for the Hyades MS …
Identification of Fe II Emission Lines in FUSE Stellar Spectra
Harper, Graham M.; Brown, Alexander; Linsky, Jeffrey L. +2 more
We identify two complexes of Fe II emission lines in far-ultraviolet spectra of the stars α TrA and HD 104237. Using spectra from both the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST), we show that these emission lines, which represent the majority of pr…
NLTE accretion disc models for the AM Canum Venaticorum systems
Nasser, M. R.; Solheim, J. -E.; Semionoff, D. A.
We present models of the optical spectra of two types of accretion disc atmospheres: a pure helium model and a H-He model, in a low mass ratio, helium transferring, interacting binary white dwarf system. The computations are restricted to stationary discs in LTE and NLTE cases. We also investigate the influence on the spectra of some of the disc p…
The variable XMM-Newton spectrum of Markarian 766
Kaastra, J. S.; Clavel, J.; Page, M. J. +10 more
The narrow-line Seyfert 1 galaxy Markarian 766 was observed for 60 ks with the \xmm\ observatory. The source shows a complex X-ray spectrum. The 2-10 keV spectrum can be adequately represented by a power law and broad Fe Kalpha emission. Between 0.7 and 2 keV the spectrum is harder and exhibits a flux deficit with respect to the extrapolated mediu…
Proper Motion and Excitation Structure of the Expanding Ionized Rings around RY Scuti
Smith, Nathan; Gehrz, Robert D.; Goss, W. M.
Multiepoch HST/WFPC2 images of the massive eclipsing binary RY Scuti reveal that the compact ionized rings in its circumstellar nebula are expanding. Radio images of the free-free continuum at 15 GHz obtained with the Very Large Array confirm the expansion rate and extend the temporal baseline. Combined Hα and radio proper-motion measurements of t…
Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures
Pitout, F.; Balogh, A.; Wild, J. A. +35 more
We study a series of transient entries into the low-latitude boundary layer (LLBL) of all four Cluster spacecraft during an outbound pass through the mid-afternoon magnetopause ( [ XGSM, YGSM, ZGSM ] <approx> [ 2, 7, 9 ] RE). The events take place during an interval of northward IMF, as seen in the data from the ACE satellite and lagged by a…