Tartalom
Képek
Kép feltöltése
DSS Images Other Images
Kapcsolódó cikkek
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.
| Distance determination for RAVE stars using stellar models . II. Most likely values assuming a standard stellar evolution scenario
The RAdial Velocity Experiment (RAVE) is a spectroscopic survey of theMilky Way which already collected over 400 000 spectra of ~ 330 000different stars. We use the subsample of spectra with spectroscopicallydetermined values of stellar parameters to determine the distances tothese stars. The list currently contains 235 064 high quality spectrawhich show no peculiarities and belong to 210 872 different stars. Thenumbers will grow as the RAVE survey progresses. The public version ofthe catalog will be made available through the CDS services along withthe ongoing RAVE public data releases. The distances are determined witha method based on the work by Breddels et al. (2010, A&A, 511, A16).Here we assume that the star undergoes a standard stellar evolution andthat its spectrum shows no peculiarities. The refinements include: theuse of either of the three isochrone sets, a better account of thestellar ages and masses, use of more realistic errors of stellarparameter values, and application to a larger dataset. The deriveddistances of both dwarfs and giants match within ~ 21% to theastrometric distances of Hipparcos stars and to the distances ofobserved members of open and globular clusters. Multiple observations ofa fraction of RAVE stars show that repeatability of the deriveddistances is even better, with half of the objects showing a distancescatter of ? 11%. RAVE dwarfs are ~ 300 pc from the Sun, and giantsare at distances of 1 to 2 kpc, and up to 10 kpc. This places the RAVEdataset between the more local Geneva-Copenhagen survey and the moredistant and fainter SDSS sample. As such it is ideal to address some ofthe fundamental questions of Galactic structure and evolution in thepre-Gaia era. Individual applications are left to separate papers, herewe show that the full 6-dimensional information on position and velocityis accurate enough to discuss the vertical structure and kinematicproperties of the thin and thick disks.The catalog is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/522/A54
| Distance determination for RAVE stars using stellar models
Aims: We develop a method for deriving distances fromspectroscopic data and obtaining full 6D phase-space coordinates for theRAVE survey's second data release. Methods: We used stellarmodels combined with atmospheric properties from RAVE (effectivetemperature, surface gravity and metallicity) and (J-Ks)photometry from archival sources to derive absolute magnitudes. Incombination with apparent magnitudes, sky coordinates, proper motionsfrom a variety of sources and radial velocities from RAVE, we are ableto derive the full 6D phase-space coordinates for a large sample of RAVEstars. This method is tested with artificial data, Hipparcostrigonometric parallaxes and observations of the open cluster M 67. Results: When we applied our method to a set of 16 146 stars, wefound that 25% (4037) of the stars have relative (statistical) distanceerrors of <35%, while 50% (8073) and 75% (12 110) have relative(statistical) errors smaller than 45% and 50%, respectively. Our varioustests show that we can reliably estimate distances for main-sequencestars, but there is an indication of potential systematic problems withgiant stars owing to uncertainties in the underlying stellar models. Forthe main-sequence star sample (defined as those with log(g) > 4), 25%(1744) have relative distance errors <31%, while 50% (3488) and 75%(5231) have relative errors smaller than 36% and 42%, respectively. Ourfull dataset shows the expected decrease in the metallicity of stars asa function of distance from the Galactic plane. The known kinematicsubstructures in the U and V velocity components of nearby dwarf starsare apparent in our dataset, confirming the accuracy of our data and thereliability of our technique. We provide independent measurements of theorientation of the UV velocity ellipsoid and of the solar motion, andthey are in very good agreement with previous work. Conclusions:The distance catalogue for the RAVE second data release is available athttp://www.astro.rug.nl/~rave,and will be updated in the future to include new data releases.
| New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
| Mining in the HIPPARCOS raw data
The Hipparcos solutions flagged as unreliable after the completion ofthe standard data processing have been systematically revisited in thelight of additional information, primarily related to theirmultiplicity. In many cases improved solutions have been obtained,yielding at the same time an Hipparcos based separation and positionangle and a better astrometric solution for the system. The principlesapplied in this reprocessing are explained and more than a hundred newsolutions with absolute and relative astrometry are presented anddiscussed. Tables 1 to 7 are also available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|
Új cikk hozzáadása
Kapcsolódó hivatkozások
- - (nincs kapcsolódó hivatkozás) -
Új link hozzáadása
Besorolás csoportokba:
|
Pozíciós és asztrometriai adatok
| Csillagkép: | Szűz |
| Rektaszcenzió: | 14h20m09.26s |
| Deklináció: | -04°52'08.6" |
| Vizuális fényesség: | 9.742 |
| RA sajátmozgás: | 0.1 |
| Dec sajátmozgás: | -87.8 |
| B-T magnitude: | 10.42 |
| V-T magnitude: | 9.798 |
Katalógusok és elnevezések:
|
