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The 0.33 Day DA Plus DME Binary BPM 6502
Vennes, Stéphane; Dupuis, Jean; Kawka, Adela +1 more
We have obtained a series of spectroscopic measurements of the high proper-motion star BPM 6502 showing Balmer emission superposed upon the absorption lines. Radial velocity measurements determined by tracing optical absorption and emission lines show that the star is a binary system comprised of a DA white dwarf and an M dwarf with an orbital per…
The evolution of iron-core white dwarfs
Althaus, L. G.; Panei, J. A.; Benvenuto, O. G.
Recent measurements by Hipparcos present observational evidence supporting the existence of some white dwarf (WD) stars with iron-rich core composition. In connection with this, the present paper is aimed at exploring the structure and evolution of iron-core WDs by means of a detailed and updated evolutionary code. In particular, we examined the e…
Hydrogen and Oxygen Temperatures in Coronal Holes
Giordano, S.; Antonucci, E.; Dodero, M. A.
The analysis of the O VI λ 1032 and 1037 and H I Ly⋋a ⋋l 1216 line profiles, observed with the Ultraviolet Coronagraph Spectrometer (UVCS) onboard the Solar Heliospheric Observatory (SOHO) in a polar coronal hole within 1.5 Rsolar and 3.5 Rsolar during the solar activity minimum, indicates the existence of a large anisotropy in the velocity distri…
Binary statistics from Hipparcos data - a progress report
Söderhjelm, S.
The Hipparcos data are an important source for constraining the statistical distribution functions for the binaries in the general field. The present study uses the resolved binaries (separation 0.1-10 arcsec, magnitude-differences below 4 mag) to check directly the frequency of main-sequence binaries with (linear) separations 30-500 a.u. and mass…
Kinematics of the Galaxy from Hipparcos Proper Motions
Zhu, Zi
From Hipparcos proper motions, we have analysed the local kinematics of the Milky Way from young O-B5 stars, classical Cepheids, and the late-type K-M giants. The components of solar motion along the direction pointing to the galactic center from the Sun u_0 and along the direction pointing to the north galactic pole w_0 are approximately 10 km s<…
Analysis of the HST Ultraviolet Spectra for T Tauri Stars: RY Tau and HD115043
Lamzin, S. A.
The ultraviolet spectra of the stars RY Tau and HD115043 from the Hubble Space Telescope are analyzed. RY Tau belongs to the classical T Tauri stars, while HD115043 is a young (t ~ 3 x 10^8 years), chromospherically active star. The most intense emission lines were identified, and their fluxes were measured. Low-resolution spectra of RY Tau and HD…
Asteroseismology of the Multiply Periodic δ Scuti Star θ Tucanae
Templeton, Matthew R.; Bradley, Paul A.; Guzik, Joyce A.
We present an asteroseismological analysis of the δ Scuti component of the binary star system θ Tucanae, using the 10 pulsational frequencies obtained photometrically by Paparó et al. and the mode identifications of Sterken. We have tested theoretical models with masses between 1.8 and 2.8 Msolar that have solar metal abundances, and we…
ISOCAM observations of the very deep IRAS 60 micron sample in the NEP region. I. The data
Aussel, H.; Franceschini, A.; De Zotti, G. +2 more
We present the results of ISO observations with the CAM LW3 filter, centered at lambda_eff = 14.3 mu m, of 94 out of the 98 galaxies comprising the complete 60 mu m IRAS deep survey (IDS) sample in the north ecliptic polar region. In addition, we observed a source detected by IRAS at 25 mu m and found to have particularly interesting properties. A…
On the Inference of Differential Emission Measures Using Diagnostic Line Ratios
McIntosh, Scott W.
Spectroscopic diagnosis of hot optically thin plasmas can be used to infer valuable information about the temperature structure of the emitting plasma volume, through the emission measure differential (DEM) in Te, DEM(Te). However, the uncertainties in atomic parameters (required to model the plasma emission) make such infere…
A New Observational Search for Vulcanoids in SOHO/LASCO Coronagraph Images
Parker, Joel Wm.; Stern, S. Alan; Levison, Harold F. +3 more
We examined SOHO/LASCO (Solar and Heliospheric Observatory/Large Angle Spectroscopic Coronagraph) C3 coronagraph images to search for the long-suspected population of small bodies, the vulcanoids, in heliocentric orbits interior to Mercury. We searched the entire vulcanoid region from 0.07-0.21 AU by visually blinking daily image averages co-regis…