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Spectroscopic parameters for 451 stars in the HARPS GTO planet search program. Stellar [Fe/H] and the frequency of exo-Neptunes
To understand the formation and evolution of solar-type stars in thesolar neighborhood, we need to measure their stellar parameters to highaccuracy. We present a catalogue of accurate stellar parameters for 451stars that represent the HARPS Guaranteed Time Observations (GTO)“high precision” sample. Spectroscopic stellar parameterswere measured using high signal-to-noise (S/N) spectra acquired with theHARPS spectrograph. The spectroscopic analysis was completed assumingLTE with a grid of Kurucz atmosphere models and the recent ARES code formeasuring line equivalent widths. We show that our results agree wellwith those ones presented in the literature (for stars in common). Wepresent a useful calibration for the effective temperature as a functionof the index color B-V and [Fe/H]. We use our results to study themetallicity-planet correlation, namely for very low mass planets. Theresults presented here suggest that in contrast to their joviancouterparts, neptune-like planets do not form preferentially aroundmetal-rich stars. The ratio of jupiter-to-neptunes is also an increasingfunction of stellar metallicity. These results are discussed in thecontext of the core-accretion model for planet formation.Based on observations collected at La Silla Observatory, ESO, Chile,with the HARPS spectrograph at the 3.6-m telescope (072.C-0488(E)). FullTables 1 and 3 are only available in electronic form at the CDS vianonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/487/373
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample
We are obtaining spectra, spectral types, and basic physical parametersfor the nearly 3600 dwarf and giant stars earlier than M0 in theHipparcos catalog within 40 pc of the Sun. Here we report on resultsfor 1676 stars in the southern hemisphere observed at Cerro TololoInter-American Observatory and Steward Observatory. These resultsinclude new, precise, homogeneous spectral types, basic physicalparameters (including the effective temperature, surface gravity, andmetallicity [M/H]), and measures of the chromospheric activity of ourprogram stars. We include notes on astrophysically interesting stars inthis sample, the metallicity distribution of the solar neighborhood, anda table of solar analogs. We also demonstrate that the bimodal nature ofthe distribution of the chromospheric activity parameterlogR'HK depends strongly on the metallicity, andwe explore the nature of the ``low-metallicity'' chromosphericallyactive K-type dwarfs.
| Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog
We complete construction of a catalog containing improved astrometry andnew optical/infrared photometry for the vast majority of NLTT starslying in the overlap of regions covered by POSS I and by the secondincremental Two Micron All Sky Survey (2MASS) release, approximately 44%of the sky. The epoch 2000 positions are typically accurate to 130 mas,the proper motions to 5.5 mas yr-1, and the V-J colors to0.25 mag. Relative proper motions of binary components are measured to 3mas yr-1. The false-identification rate is ~1% for11<~V<~18 and substantially less at brighter magnitudes. Theseimprovements permit the construction of a reduced proper-motion diagramthat, for the first time, allows one to classify NLTT stars intomain-sequence (MS) stars, subdwarfs (SDs), and white dwarfs (WDs). We inturn use this diagram to analyze the properties of both our catalog andthe NLTT catalog on which it is based. In sharp contrast to popularbelief, we find that NLTT incompleteness in the plane is almostcompletely concentrated in MS stars, and that SDs and WDs are detectedalmost uniformly over the sky δ>-33deg. Our catalogwill therefore provide a powerful tool to probe these populationsstatistically, as well as to reliably identify individual SDs and WDs.
| The Vienna-KPNO search for Doppler-imaging candidate stars. I. A catalog of stellar-activity indicators for 1058 late-type Hipparcos stars
We present the results from a spectroscopic Ca ii H&K survey of 1058late-type stars selected from a color-limited subsample of the Hipparcoscatalog. Out of these 1058 stars, 371 stars were found to showsignificant H&K emission, most of them previously unknown; 23% withstrong emission, 36% with moderate emission, and 41% with weak emission.These spectra are used to determine absolute H&K emission-linefluxes, radial velocities, and equivalent widths of theluminosity-sensitive Sr ii line at 4077 Ä. Red-wavelengthspectroscopic and Strömgren y photometric follow-up observations ofthe 371 stars with H&K emission are used to additionally determinethe absolute Hα -core flux, the lithium abundance from the Li i6708 Å equivalent width, the rotational velocity vsin i, theradial velocity, and the light variations and its periodicity. Thelatter is interpreted as the stellar rotation period due to aninhomogeneous surface brightness distribution. 156 stars were found withphotometric periods between 0.29 and 64 days, 11 additional systemsshowed quasi-periodic variations possibly in excess of ~50 days. Further54 stars had variations but no unique period was found, and four starswere essentially constant. Altogether, 170 new variable stars werediscovered. Additionally, we found 17 new SB1 (plus 16 new candidates)and 19 new SB2 systems, as well as one definite and two possible new SB3systems. Finally, we present a list of 21 stars that we think are mostsuitable candidates for a detailed study with the Doppler-imagingtechnique. Tables A1--A3 are only 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
| Dwarf K and M stars in the southern hemisphere.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972AJ.....77..486U&db_key=AST
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Osservazione e dati astrometrici
| Costellazione: | Cane Maggiore |
| Ascensione retta: | 06h52m59.64s |
| Declinazione: | -23°06'27.7" |
| Magnitudine apparente: | 9.018 |
| Distanza: | 31.636 parsec |
| Moto proprio RA: | 218.1 |
| Moto proprio Dec: | 77.8 |
| B-T magnitude: | 10.215 |
| V-T magnitude: | 9.117 |
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