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The RAdial Velocity Experiment (RAVE): Third Data Release
We present the third data release of the RAdial Velocity Experiment(RAVE) which is the first milestone of the RAVE project, releasing thefull pilot survey. The catalog contains 83,072 radial velocitymeasurements for 77,461 stars in the southern celestial hemisphere, aswell as stellar parameters for 39,833 stars. This paper describes thecontent of the new release, the new processing pipeline, as well as anupdated calibration for the metallicity based upon the observation ofadditional standard stars. Spectra will be made available in a futurerelease. The data release can be accessed via the RAVE Web site.
| The Chromospheric Activity, Age, Metallicity, and Space Motions of 36 Wide Binaries
We present the chromospheric activity (CA) levels, metallicities, andfull space motions for 41 F, G, K, and M dwarf stars in 36 wide binarysystems. Thirty-one of the binaries contain a white dwarf (WD)component. In such binaries, the total age can be estimated by addingthe cooling age of the WD to an estimate of the progenitor'smain-sequence lifetime. To better understand how CA correlates tostellar age, 14 cluster member stars were also observed. Ourobservations demonstrate for the first time that, in general, CA decayswith age from 50 Myr to at least 8 Gyr for stars with 1.0 <= V - I<= 2.4. However, little change occurs in the CA level for stars withV - I < 1.0 between 1 Gyr and 5 Gyr, consistent with the results ofPace et al. Our sample also exhibits a negative correlation between thestellar age and metallicity, a positive correlation between the stellarage and W space velocity component, and the W velocity dispersionincreases with age. Finally, the population membership of these widebinaries is examined based upon their U, V, W kinematics, metallicity,and CA. We conclude that wide binaries are similar to field and clusterstars in these respects. More importantly, they span a much morecontinuous range in age and metallicity than is afforded by nearbyclusters.
| Bayesian inference of stellar parameters and interstellar extinction using parallaxes and multiband photometry
Astrometric surveys provide the opportunity to measure the absolutemagnitudes of large numbers of stars, but only if the individualline-of-sight extinctions are known. Unfortunately, extinction is highlydegenerate with stellar effective temperature when estimated frombroad-band optical/infrared photometry. To address this problem, Iintroduce a Bayesian method for estimating the intrinsic parameters of astar and its line-of-sight extinction. It uses both photometry andparallaxes in a self-consistent manner in order to provide anon-parametric posterior probability distribution over the parameters.The method makes explicit use of domain knowledge by employing theHertzsprung-Russell Diagram (HRD) to constrain solutions and to ensurethat they respect stellar physics. I first demonstrate this method byusing it to estimate effective temperature and extinction from BVJHKdata for a set of artificially reddened Hipparcos stars, for whichaccurate effective temperatures have been estimated from high-resolutionspectroscopy. Using just the four colours, we see the expected strongdegeneracy (positive correlation) between the temperature andextinction. Introducing the parallax, apparent magnitude and the HRDreduces this degeneracy and improves both the precision (reduces theerror bars) and the accuracy of the parameter estimates, the latter byabout 35 per cent. The resulting accuracy is about 200 K in temperatureand 0.2 mag in extinction. I then apply the method to estimate theseparameters and absolute magnitudes for some 47 000 F, G, K Hipparcosstars which have been cross-matched with Two-Micron All-Sky Survey(2MASS). The method can easily be extended to incorporate the estimationof other parameters, in particular metallicity and surface gravity,making it particularly suitable for the analysis of the 109stars from Gaia.
| Ca II H and K Filter Photometry on the UVBY System. II. The Catalog of Observations
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....109.2828T&db_key=AST
| Gravitational redshift determinations for white dwarfs in common proper-motion binaries
Gravitational redshifts determined using the 5 m Hale telescope aregiven for 23 white dwarfs belonging to common proper-motion binarysystems and additional velocities are presented for 14 pairs found notto comprise physical binaries or that have unmeasurable velocities. Themass distribution for the common proper-motion pairs using thegravitational redshifts and the mass-radius relation peaks strongly near0.55 solar mass, and the main details of the shape agree with earlierdeterminations using other methods although a problem remains withcontamination with optical pairs. The redshifts and radii of a subset ofthese objects with known distances are consistent with the mass-radiusrelation for white dwarfs.
| Observations of proper-motion stars. II.
Abstract image available at:http://adsabs.harvard.edu/abs/1965ApJ...142..925E
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| Сазвежђа: | Хидра |
| Ректацензија: | 09h00m46.83s |
| Deклинација: | -04°22'13.3" |
| Apparent магнитуда: | 10.189 |
| Proper motion RA: | 70.1 |
| Proper motion Dec: | -62.8 |
| B-T magnitude: | 10.847 |
| V-T magnitude: | 10.244 |
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INHABITED SKY
