Search Publications
Search for reference A0 dwarf stars: Masses and luminosities revisited with HIPPARCOS parallaxes
Gerbaldi, M.; Faraggiana, R.; Grenier, S. +3 more
Hipparcos data for 71 nearby dwarf A0 stars were combined with other data, in particular with high resolution spectra to establish the HR diagram in this temperature range. Almost 30% of unknown binaries were detected and discarded before establishing the cal M-L relation for bright A0 V field stars. The relationship derived for these single stars…
A determination of the outflow speeds in the lower solar wind
Simnett, G. M.; Tappin, S. J.; Lyons, M. A.
The acceleration of the low-latitude solar wind, which comes from regions of the corona above large, closed magnetic loops, is a theoretical challenge. Until recently we have lacked direct measurements close to the Sun with which to constrain the theory. When a series of high-resolution coronagraph images is viewed in the form of a movie the conti…
Characterization of variable stars by robust wave variograms: an application to HIPPARCOS mission
Eyer, L.; Genton, M. G.
Variogram analysis is applied to time series of variable stars. This method allows to characterize time-scales of varying signals. It is well suited for periodic and pseudo-periodic signals. The aspects of robustness, bin positions and bin widths for the variogram estimator are assessed, evaluated with the help of simulations and adapted to the Hi…
Intensity oscillations in a sunspot plume
Fludra, A.
Observations of a sunspot plume (a compact feature, bright in the transition region line of O V 629.7 Angstroms at 2.2 x 10(5) K), seen above a sunspot in the active region AR8249, have been made with a 15-second time resolution with the Coronal Diagnostic Spectrometer on SOHO. Intensity of the O V 629.7 Angstroms line in the sunspot plume oscilla…
Young Stellar Nuclei in the Lenticular Galaxies. I. NGC 1023 and NGC 7332
Sil'chenko, O. K.
As a result of bidimensional spectroscopy of the central parts of two nearby lenticular galaxies, NGC 1023 and NGC 7332, undertaken with the Multi-Pupil Field Spectrograph of the 6 m telescope of the Special Astrophysical Observatory, their chemically decoupled stellar nuclei are found to be substantially younger than the surrounding bulges: the m…
Imaging Observations of Asteroids with Hubble Space Telescope
Storrs, Alex; Tholen, David; Weiss, Ben +5 more
We present the results of two Hubble Space Telescope (HST) observing programs, consisting of 11 imaging observations of 10 asteroids. The primary focus of the projects was to search for faint companions (satellites) of these asteroids. No binary systems were detected. More specifically, no companions were found at more than 0.1 arcsec separation o…
LASCO observations of the coronal rotation
Simnett, G. M.; Schwenn, R.; Lamy, P. L. +3 more
The near-rigid rotation of the corona above the differential rotation of the photosphere has important implications for the form of the global coronal magnetic field. The magnetic reconfiguring associated with the shear region where the rigidly-rotating coronal field lines interface with the differentially-rotating photospheric field lines could p…
Forming the Dusty Ring in HR 4796A
Wood, Kenneth; Wolff, Michael J.; Kenyon, Scott J. +1 more
We describe planetesimal accretion calculations for the dusty ring observed in the nearby A0 star HR 4796A. Models with initial masses of 10-20 times the minimum-mass solar nebula produce a ring with a width of 7-15 AU and a height of 0.3-0.6 AU at 70 AU in ~10 Myr. The ring has a radial optical depth of ~1. These results agree with limits derived…
A deep 12 micron survey with ISO
Cesarsky, C.; Clements, D. L.; Reach, W. T. +4 more
We present the first results of a study of faint 12 mu m sources detected with the Infrared Space Observatory (ISO) in four deep, high galactic latitude fields. The sample includes 50 such sources in an area of 0.1 square degrees down to a 5sigma flux limit of ~ 500 mu Jy. From optical identifications based on the US Naval Observatory (USNO) catal…
Identification of trailing edge solar wind stream interfaces: A comparison of Ulysses plasma and composition measurements
Crooker, N. U.; Burton, M. E.; Smith, E. J. +2 more
Measurements of the specific entropy argument of the solar wind protons, T/nγ-1, reveal that nearly every occurrence of a high-speed stream seen at Ulysses in 1992-1993 is characterized by an abrupt interface at its trailing edge. These observations, made by the solar wind plasma instrument (SWOOPS), at a heliocentric range of 4.5 to 5 …