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Zero-point and external errors of HIPPARCOS parallaxes
Arenou, F.; Lindegren, L.; Turon, C. +4 more
A good knowledge of both accuracy and precision of the Hipparcos parallaxes is one of the keys for their future scientific use. For this purpose, the Hipparcos preliminary parallaxes, as obtained after the processing of the first 30 months of Hipparcos data, are compared to various ground-based parallax estimates, using astrometric, photometric an…
Linking the HIPPARCOS Catalogue to the extragalactic reference system.
Lindegren, L.; Kovalevsky, J.
We present an overview of the methods currently planned to link the Hipparcos reference system to the conventional extragalactic reference system, as defined by VLBI observations. The link programme consists of VLBI and connected element interferometry of radio stars, separation measurements with the Hubble Space Telescope, photographic observatio…
Intermittent turbulence in solar wind from the south polar hole
Balogh, A.; Smith, E. J.; Goldstein, B. E. +2 more
The magnetic fields measured by the Ulysses spacecraft are used to study solar wind turbulence in the fast solar wind from the south polar hole. The spacecraft was at about 46 deg south latitude and 3.9 AU. For a magnetic field with a Gaussian distribution the power spectrum (second-order structure function) is sufficient to completely characteriz…
HST Observations of the Stellar Population of the Globular Cluster W CEN
Casertano, Stefano; Elson, Rebecca A. W.; Gilmore, Gerard F. +1 more
We present a luminosity function for ∼4000 stars ∼3-5 half-mass radii from the center of the globular cluster co Cen (NGC 5139), based on images obtained with the Rubble Space Telescope's Planetary Camera as part of the Medium Deep Survey Key Project. The luminosity function (corrected for incompleteness) has a plateau at 5<MI<7, …
Low mass stars in globular clusters. II. The mass function of M15.
Paresce, F.; de Marchi, G.
We have used the WFPC2 on board HST to investigate the stellar population in a field located 4.6' NW of the center of the globular cluster M15 by means of deep imaging in wide bands centered at 606 and 812nm. A total of 7770 stars are accurately classified by two-color photometry to form a color-magnitude diagram extending down to a limiting magni…
Hubble Space Telescope and R-Band Eclipse Maps of the UX Ursae Majoris Accretion Disk
Horne, Keith; Baptista, R.; Mason, K. O. +2 more
Hubble Space Telescope time-resolved spectroscopic and ground-based R-band photometric data of UX UMa during eclipse are presented and discussed. The spectroscopy covers the C IV λ1550 and He II λ1640 spectral regions. The eclipses in the UV continuum are deep, nearly reaching the zero level at mid-eclipse phases. Sharp ingress and egress features…
B[e] phenomenon extending to lower luminosities in the Magellanic Clouds.
Zickgraf, F. -J.; Wolf, B.; Gummersbach, C. A.
An analysis of the four recently discovered B[e] stars HenS35, S59, S93, and S137 in the Large Magellanic Cloud has been carried out using low-resolution IUE spectra, ESO 3.6-m CASPEC spectra, and ESO 0.5-m and 1-m UBV and JHK photometry, respectively. LTE model atmospheres have been fitted to the observed continuum energy distributions in order t…
CCD photometry of the δ-Scuti star κ^2^ Bootis.
Kjeldsen, H.; Hjorth, J.; Thomsen, B. +4 more
CCD time-series differential photometry of the binary star κBoo has been carried out from a small in town situated telescope. One component of the system is known to be a δ-Scuti pulsator. Due to the high S/N data, four frequencies have been detected even though the window function is quite complicated. A search for a standard model that fits all …
Si/O Abundance Ratios in Extragalactic H II Regions from Hubble Space Telescope UV Spectroscopy
Terlevich, E.; Garnett, D. R.; Skillman, E. D. +5 more
We have measured the Si III] intercombination doublet at 1883 A and 1892 A in seven extragalactic H II regions using the Faint Object Spectrograph on the Hubble Space Telescope. These measurements were used to derive the Si/C and Si/O gas phase abundance ratios in the ionized gas. We find that Si/O shows no systematic variation with O/H over the r…
The flux of interstellar dust observed by ULYSSES and Galileo
Hamilton, D. P.; Grün, E.; Linkert, G. +4 more
Interstellar dust detected by the dust sensor onboard Ulysses was first identified after the Jupiter flyby when the spacecraft's trajectory changed dramatically (Grün et al., 1994). Here we report on two years of Ulysses post-Jupiter data covering the range of ecliptic latitudes from 0° to -54° and distances from 5.4 to 3.2 AU. We find that, over …