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מאמרים קשורים
Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of 14 000 F and G dwarfs
We present and discuss new determinations of metallicity, rotation, age,kinematics, and Galactic orbits for a complete, magnitude-limited, andkinematically unbiased sample of 16 682 nearby F and G dwarf stars. Our63 000 new, accurate radial-velocity observations for nearly 13 500stars allow identification of most of the binary stars in the sampleand, together with published uvbyβ photometry, Hipparcosparallaxes, Tycho-2 proper motions, and a few earlier radial velocities,complete the kinematic information for 14 139 stars. These high-qualityvelocity data are supplemented by effective temperatures andmetallicities newly derived from recent and/or revised calibrations. Theremaining stars either lack Hipparcos data or have fast rotation. Amajor effort has been devoted to the determination of new isochrone agesfor all stars for which this is possible. Particular attention has beengiven to a realistic treatment of statistical biases and errorestimates, as standard techniques tend to underestimate these effectsand introduce spurious features in the age distributions. Our ages agreewell with those by Edvardsson et al. (\cite{edv93}), despite severalastrophysical and computational improvements since then. We demonstrate,however, how strong observational and theoretical biases cause thedistribution of the observed ages to be very different from that of thetrue age distribution of the sample. Among the many basic relations ofthe Galactic disk that can be reinvestigated from the data presentedhere, we revisit the metallicity distribution of the G dwarfs and theage-metallicity, age-velocity, and metallicity-velocity relations of theSolar neighbourhood. Our first results confirm the lack of metal-poor Gdwarfs relative to closed-box model predictions (the ``G dwarfproblem''), the existence of radial metallicity gradients in the disk,the small change in mean metallicity of the thin disk since itsformation and the substantial scatter in metallicity at all ages, andthe continuing kinematic heating of the thin disk with an efficiencyconsistent with that expected for a combination of spiral arms and giantmolecular clouds. Distinct features in the distribution of the Vcomponent of the space motion are extended in age and metallicity,corresponding to the effects of stochastic spiral waves rather thanclassical moving groups, and may complicate the identification ofthick-disk stars from kinematic criteria. More advanced analyses of thisrich material will require careful simulations of the selection criteriafor the sample and the distribution of observational errors.Based on observations made with the Danish 1.5-m telescope at ESO, LaSilla, Chile, and with the Swiss 1-m telescope at Observatoire deHaute-Provence, France.Complete Tables 1 and 2 are only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/989
| Five-colour photometry of OB-stars in the Southern Hemisphere
Observations of OB-stars, made in 1959 and 1960 at the Leiden SouthernStation near Hartebeespoortdam, South Africa, with the VBLUW photometerattached to the 90 cm light-collector, are given in this paper. They arecompared with photometry obtained by \cite[Graham (1968),]{gra68}\cite[Walraven & Walraven (1977),]{wal77} \cite[Lub & Pel(1977)]{lub77} and \cite[Van Genderen et al. (1984).]{gen84} Formulaefor the transformation of the present observations to those of\cite[Walraven & Walraven (1977)]{wal77} and \cite[Lub & Pel(1977)]{lub77} are given. Table 4 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/Abstract.html
| Discovery of Two New, Carbon-rich Proto-Planetary Nebulae:IRAS Z02229+6208 and IRAS 07430+1115
We report the discovery of two new carbon-rich proto-planetary nebulae(PPNs), IRAS Z02229+6208 and 07430+1115. Optical spectroscopy of thesesources and another previously discovered PPN, IRAS 05431+0852, revealsthe presence of C_2 and C_3 in absorption. All three objects have thespectra of G-K supergiants, consistent with the expectations of theirbeing PPNs. New ground-based optical and infrared photometry, combinedwith the IRAS measurements, show double-peak spectral energydistributions for each; this suggests that the asymptotic giant branch(AGB) mass loss has ended and these objects are in the post-AGB phase ofevolution. The remnant of the molecular envelope is detected in COemission for the first time in all three objects, using the CO (3-2)line. The 3.3 and 11.3 μm emission features commonly attributed tothe polycyclic aromatic hydrocarbon molecules have been detected in IRAS07430+1115. Strikingly absent in IRAS 07430+1115, however, is the 21μm emission feature, found in the other two and in all but one of theother PPNs known to show C_2 in absorption.
| A preliminary compilation of DS-programme star positions
A catalog is presented of the double-star-program (DS-program) starpositions, listing right ascensions for 930 DSs and declinations for1225 DSs of the program. The positions were compiled from the observedvalues obtained between 1980 and 1987 with the meridian circles of sixUSSR observatories (the Moscow, Kazan', Kiev, Khar'kov, Odessa, andTashkent Observatories) and the Belgrade Observatory. The measurementsand the treatment of the observational material were performed using therelative method, and the FK-4 system stars were used as reference stars.
| The absolute spectrophotometric study of binary stars around Gamma CAS in the UV and visible ranges
Results of absolute spectrophotometric measurements of 15 binary starsof the classes F, G, and K in the 2300-4800 A wavelength interval arepresented. The absolute energy distributions of the stars studied in theUV and visible range were compared with Kurucz's (1979) theoreticalmodels. Spectral and luminosity classes of the system components areestimated by constructing the combined spectra.
| Hydrogen Emissions on Low-Dispersion Spectrograms of B-Stars
Not Available
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הכנס מאמר חדש
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הכנס לינק חדש
משמש של הקבוצה הבאה
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | קאסיופיאה |
| התרוממות ימנית: | 00h49m39.53s |
| סירוב: | +60°45'32.6" |
| גודל גלוי: | 8.057 |
| מרחק: | 135.87 פארסק |
| תנועה נכונה: | 21 |
| תנועה נכונה: | -16.5 |
| B-T magnitude: | 8.698 |
| V-T magnitude: | 8.11 |
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