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A Uniform Analysis of 118 Stars with High-contrast Imaging: Long-period Extrasolar Giant Planets are Rare Around Sun-like Stars
We expand on the results of Nielsen et al., using the null result forgiant extrasolar planets around the 118 target stars from the Very LargeTelescope (VLT) NACO H- and Ks-band planet search (conducted byMasciadri and collaborators in 2003 and 2004), the VLT and MMTSimultaneous Differential Imager survey, and the Gemini Deep PlanetSurvey to set constraints on the population of giant extrasolar planets.Our analysis is extended to include the planet luminosity models ofFortney et al., as well as the correlation between stellar mass andfrequency of giant planets found by Johnson et al. Doubling the samplesize of FGKM stars strengthens our conclusions: a model for extrasolargiant planets with power laws for mass and semimajor axis as given byCumming et al. cannot, with 95% confidence, have planets beyond 65 AU,compared to the value of 94 AU reported by Nielsen et al., using themodels of Baraffe et al. When the Johnson et al. correction for stellarmass (which gives fewer Jupiter-mass companions to M stars with respectto solar-type stars) is applied, however, this limit moves out to 82 AU.For the relatively new Fortney et al. models, which predict fainterplanets across most of parameter space, these upper limits, with andwithout a correction for stellar mass, are 182 and 234 AU, respectively.
| 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.
| Dwarf K and M stars of high proper motion found in a hemispheric survey
A recently completed visual/red spectral region objective-prism surveyof more than half the sky found some 2200 dwarf K and M stars ofnegligible proper motion (Stephenson, 1986). The present paper adds the1800-odd spectroscopically identified dwarfs that did prove to havesignificant proper motions. About half of these had previous spectralclassifications of some sort, especially by Vyssotsky (1952, 1956). Forthe great majority, the present coordinates are more accurate thanprevious data. The paper includes about 50 stars with unpublishedparallaxes, likely to have parallaxes of 0.05 arcsec or more. Combiningthe present data with the first paper suggests that the number oflow-proper-motion stars in that paper was not unreasonable.
| 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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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | נחש מים |
| התרוממות ימנית: | 10h47m25.39s |
| סירוב: | -22°17'12.1" |
| גודל גלוי: | 9.965 |
| מרחק: | 32.712 פארסק |
| תנועה נכונה: | -126.7 |
| תנועה נכונה: | -27.5 |
| B-T magnitude: | 11.548 |
| V-T magnitude: | 10.096 |
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