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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.
| 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.
| New light on faint stars. I - The luminosity function in the solar neighbourhood
From photoelectric photometry of red dwarf stars identified in anobjective prism survey, a magnitude-limited complete sample has beendefined. Applying photometric parallaxes, calibrated for theKron-Cousins system by observations of trigonometric parallax stars,this sample is used to determine the space densities of stars withabsolute magnitudes between + 7 and + 12. The resultant luminosityfunction is consistent with the Luyten and Wielen functions for thesolar neighbourhood. An analysis of the stellar kinematics shows littlesignificant evidence of a substantial local population of low spacemotion M-dwarfs.
| Photometry of Southern Hemisphere red dwarf stars
Results are presented for a photometric investigation of aspectroscopically selected sample of red dwarf stars in the SouthernHemisphere. Absolute magnitudes and distances for the stars areestimated from broadband red colors. Three stars which may besubluminous are identified, as are several stars which may be within 25pc. The tangential velocity and velocity dispersion of the sample aresimilar to values found in other studies of nearby late-type stars.
| The space density and kinematics of dwarf M stars
The results of an objective-prism survey for dwarf stars, K7 and later,are presented. One hundred twenty-one red sensitive plates covering 1720sq. degrees of the southern sky were obtained with the Curtis Schmidttelescope at C.T.I.O. The resulting luminosity function rises from log N+ 10 = 7.9 at MV = 8 to about 8.7 at MV = 11 and12. About 75% of the dwarfs in this survey are identified with BPMstars, but inserting the proper motions given into the equations of themethod of mean absolute magnitudes yields values of MB aboutthree magnitudes brighter than the spectral types would indicate. Thatthe method of mean absolute magnitudes appears to be calibrated on starsof higher than average proper motion lends credence to the luminosityfunction result. A galactic mass density is found for the dwarfsconsidered.
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| Takýmyýldýz: | Hintli |
| Sað Açýklýk: | 21h29m51.71s |
| Yükselim: | -55°01'01.5" |
| Görünürdeki Parlaklýk: | 11.721 |
| Uzaklýk: | 47.642 parsek |
| özdevim Sað Açýklýk: | 101.4 |
| özdevim Yükselim: | -42.8 |
| B-T magnitude: | 13.725 |
| V-T magnitude: | 11.887 |
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