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Kinematic Substructure of Halo Stars from HIPPARCOS Observations
Chen, B.
With highly accurate parallaxes and proper motions observed by HIPPARCOS, we discuss the distributions of velocities and metallicities for a sample of stars selected from the Lowell Proper Motion Catalog. Cluster analysis is used to search for natural groups in the sample and display them graphically. Data presented in this Letter support the pict…
The Cassini Ion Mass Spectrometer: Performance Metrics and Techniques
McComas, D. J.; Young, D. T.; Goldstein, R. +7 more
The Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer (IMS) uses a unique electric field configuration coupled with precise sub-nanosecond timing to produce a high mass-resolution plasma analyzer with both broad energy and mass ranges. The IMS maintains a spectrographic mass resolution (m/Δm) of ≥50 over a mass range of 1 to 40amu for singl…
Synoptic measurements of Martian winds using the Hubble Space Telescope
Crisp, David; Bell, James F., III; Mischna, Michael A. +1 more
We used the Hubble Space Telescope to make wind speed and wind direction measurements of the Martian atmosphere during early northern summer (Ls=97°). Our strategy utilized a series of near-UV images with optimal temporal sampling to track observable cloud features and to determine the direction and speed of cloud motion. Several techni…
Ulysses and WIND particle observations of the November 1997 solar events
Lario, D.; Balogh, A.; Maksimovic, M. +5 more
The episode of intense solar activity on 4 and 6 November 1997 resulted in large and extended particle events observed by the Ulysses and WIND spacecraft. Ulysses was at a heliocentric distance of 5.34 AU, very close to the solar equator and 100° west in heliolongitude from earth. WIND was near the earth at 0.99 AU from the Sun and in the ecliptic…
PAH's and Crystalline Silicates in Planetary Nebulae
Beintema, D. A.
An overview is given of the PAH and crystalline silicate emissions seen in the SWS guaranteed-time programme on planetary nebulae. Of the 9 objects on which good continuum measurements were obtained above 29 µm, 7 show evidence of olivine emission at 33.5 µm. PAH emission is seen in 5 of these objects, 3 objects show both PAH's and olivines. The p…
The art of fitting p-mode spectra. II. Leakage and noise covariance matrices
Appourchaux, T.; Gizon, L.; Rabello-Soares, M. -C.
In Part I we have developed a theory for fitting p-mode Fourier spectra assuming that these spectra have a multi-normal distribution. We showed, using Monte-Carlo simulations, how one can obtain p-mode parameters using ``Maximum Likelihood Estimators". In this article, hereafter Part II, we show how to use the theory developed in Part I for fittin…
Molecules in AGB Stars Observed with ISO
Cernicharo, J.
I present in this review the recent results obtained with ISO concerning gas phase molecules in evolved stars. The near, medium and far-infrared spectrum of C-rich and O-rich stars can provide a very important information on the molecular content of these objects. Detailed models for the envelopes of AGB stars are also presented. I also report the…
F, G and K stars in the ROSAT all-sky survey. I. Photometry
Pasquini, L.; Krautter, J.; Cutispoto, G. +2 more
We present accurate BV(RI)_c photometry for a sample of F, G and K stars detected in selected areas of the ROSAT all-sky survey (RASS). We have used the photometry, in addition to low-resolution spectroscopy, to estimate spectral classifications, distances and X-ray luminosities. The log (L_X / L_V) in the sample lies below -2. Although the sample…
ISO Observations of Wolf-Rayet Dust Shells
Morris, P. W.; van der Hucht, K. A.; Williams, P. M.
Observations of circumstellar dust clouds of Wolf-Rayet stars made with the Short Wavelength Spectrometer on ISO reveal a subtle variety of spectral energy distributions not evident from ground-based observations. The modelling of these using the radiative transfer code "Dusty" by Ivezić, Nenkova & Elitzur is reported. The results are used to …
The Calibration of the Hubble Space Telescope Kuiper Belt Object Search: Setting the Record Straight
Stern, S. Alan; Levison, Harold F.; Tamblyn, Peter +2 more
The limiting magnitude of the Hubble Space Telescope (HST) data set used by Cochran and coworkers in 1995 to detect small objects in the Kuiper belt is reevaluated, and the methods used are described in detail. It is shown, by implanting artificial objects in the original HST images and rereducing the images using our original algorithm, that the …