The N2K Consortium. VII. Atmospheric Parameters of 1907 Metal-rich Stars: Finding Planet-Search Targets
We report high-precision atmospheric parameters for 1907 stars in theN2K low-resolution spectroscopic survey, designed to identify metal-richFGK dwarfs likely to harbor detectable planets. Of these stars, 284 arein the ideal temperature range for planet searches,Teff<=6000 K, and have a 10% or greater probability ofhosting planets based on their metallicities. The stars in thelow-resolution spectroscopic survey should eventually yield >60 newplanets, including 8-9 hot Jupiters. Short-period planets have alreadybeen discovered orbiting the survey targets HIP 14810 and HD 149143.
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Kinematics of Hipparcos Visual Binaries. II. Stars with Ground-Based Orbital Solutions
This paper continues kinematical investigations of the Hipparcos visualbinaries with known orbits. A sample, consisting of 804 binary systemswith orbital elements determined from ground-based observations, isselected. The mean relative error of their parallaxes is about 12% andthe mean relative error of proper motions is about 4%. However, even 41%of the sample stars lack radial velocity measurements. The computedGalactic velocity components and other kinematical parameters are usedto divide the stars with known radial velocities into kinematical agegroups. The majority (92%) of binaries from the sample are thin diskstars, 7.6% have thick disk kinematics and only two binaries have halokinematics. Among them, the long-period variable Mira Ceti has a verydiscordant {Hipparcos} and ground-based parallax values. From the wholesample, 60 stars are ascribed to the thick disk and halo population.There is an urgent need to increase the number of the identified halobinaries with known orbits and substantially improve the situation withradial velocity data for stars with known orbits.
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Irradiation and mass transfer in low-mass compact binaries
This paper studies the reaction of low-mass stars to anisotropicirradiation and its implications for the long-term evolution of compactbinaries (cataclysmic variables and low-mass X-ray binaries). First, weshow by means of simple homology considerations that if the energyoutflow through the surface layers of a low-mass main sequence star isblocked over a fraction seff < 1 of its surface (e.g. as aconsequence of anisotropic irradiation) it will inflate only modestly,by a factor ~ (1-seff)-0.1. The maximumcontribution to mass transfer of the thermal relaxation of the donorstar is seff times what one obtains for isotropic(seff = 1) irradiation. The duration of thisirradiation-enhanced mass transfer is of the order of 0.1| ln(1 -seff)| times the thermal time scale of the convectiveenvelope. Numerical computations involving full 1D stellar modelsconfirm these results. Second, we present a simple analytic one-zonemodel for computing the blocking effect by irradiation which givesresults in acceptable quantitative agreement with detailed numericalcomputations. Third, we show in a detailed stability analysis that ifmass transfer is not strongly enhanced by consequential angular momentumlosses, cataclysmic variables are stable against irradiation-inducedrunaway mass transfer if the mass of the main sequence donor is M < ~0.7Msun. If M > ~ 0.7Msun systems may beunstable, subject to the efficiency of irradiation. Low-mass X-raybinaries, despite providing much higher irradiating fluxes, are evenless susceptible to this instability. If a binary is unstable, masstransfer must evolve through a limit cycle in which phases ofirradiation- induced high mass transfer alternate with phases of small(or no) mass transfer. At the peak rate mass transfer proceeds onseff times the thermal time scale rate of the convectiveenvelope. A necessary condition for the cycles to be maintained is thatthis time scale has to be much shorter (<~ 0.05) than the time scaleon which mass transfer is driven.
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Photometric and polarimetric observations of double and multiple stars.
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New orbits.
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New orbits.
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Mesures d'etoiles doubles faites aux lunettes de 74 et 50 CM de l'Observatoire de la Cote d'Azur
We give 657 measurements of double stars, Table 1 by R. Gili with CCDcamera, Table 2 by P. Couteau with filar micrometer. Tables 1 and 2 areonly available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html.
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Photometric and Polarimetric Observations of 17 Double and Multiple Stars
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Mesures d'etoiles doubles faites a Nice, etoiles doubles nouvelles (24eme serie) decouvertes a Nice.
Table 1 gives 1182 measurements of 682 binaries observed with the 74 and50 cm refractors. Table 2 lists 26 new binaries discovered with the 50cm refractor.
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Binary-star measurements carried out at PIC DU Midi and at Nice
Data on 219 measurements of 103 close binaries observed with the 2mtelescope at Pic du Midi are presented. Also presented are data on 230measurements of 126 binaries observed with the 74 cm refractor of theNice Observatory.
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Measurements of binary stars obtained at Pic-du-Midi and at Nice
A total of 112 visual measurements of 82 close binaries observed with 2mtelescope at Pic-du-Midi are presented. In addition, 344 measurements of163 close binaries were observed with the 74-cm and 50-cm refractors atNice. All measurements were made by a micrometer with illuminated wires.
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Measurements of visual double stars made at PIC DU Midi and at Nice
Fifty visual measures of 37 very close binaries observed with the 2-mtelescope at Pic du Midi are presented together with 601 measures of 245close binaries observed with the 74-cm and 50-cm refractors at Nice. Allmeasurements were made by micrometer with illuminated wires. With the2-m telescope, binaries as close as 0.07 arcsec are separated, usingmagnifying powers from 2500 to 5000.
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Measurements of double stars at Nice with 74-cm and 50-cm refractors
A total of 717 measures of 287 binaries made at the 74-cm and 50-cmrefractors are presented. These are mostly very close binariesdiscovered recently, for which a rapid orbital motion is evident forabout 30 percent.
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New Double Stars Discovered at Nice - Part Sixteen
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981A&AS...43...79C&db_key=AST
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INHABITED SKY
