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Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity
We present rotational and radial velocities for a sample of 761 giantsselected from the Hipparcos Catalogue to lie within 100 pc of the Sun.Our original goal was to examine stellar rotation in field giants usingspectroscopic line broadening to look for evidence of excess rotationthat could be attributed to planets that were engulfed as the parentstars expanded. Thus we were obliged to investigate other sources ofline broadening, including tidal coupling in close binaries andmacroturbulence. For all the binaries in our sample with periods shorterthan 20 days the orbits have been circularized, while about half theorbits with periods in the range 20-100 days still show significanteccentricity. All our primaries in orbits shorter than 30 days show linebroadening consistent with synchronized rotation, while about half theprimaries with periods in the range 30-120 days are synchronized. Tostudy the dependence of rotation on stellar evolution when tidal effectsare not important, we used a subsample of single stars and members inwide binaries. We found evidence to suggest that the first dredge-up mayplay a role in speeding up the rotation of the observable outer layersof giants and that the rotational velocity of horizontal branch stars islarger by a few km s-1 than that of first-ascent giants withsimilar mass, effective temperature, and radius. Finally, we found threegiants that rotate more rapidly than expected. We conjecture that theyacquired their excess angular momentum by ingesting planets.Some of the results presented here used observations made with theMultiple Mirror Telescope, a joint facility of the SmithsonianInstitution and the University of Arizona.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| SB9: The ninth catalogue of spectroscopic binary orbits
The Ninth Catalogue of Spectroscopic Binary Orbits(http://sb9.astro.ulb.ac.be) continues the series of compilations ofspectroscopic orbits carried out over the past 35 years by Batten andcollaborators. As of 2004 May 1st, the new Catalogue holds orbits for2386 systems. Some essential differences between this catalogue and itspredecessors are outlined and three straightforward applications arepresented: (1) completeness assessment: period distribution of SB1s andSB2s; (2) shortest periods across the H-R diagram; (3)period-eccentricity relation.
| Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
| Ages of Late Spectral Type Vega-like Stars
We have estimated the ages of eight late-type Vega-like stars by usingstandard age-dating methods for single late-type stars, e.g., locationon the color-magnitude diagram, Li λ6708 absorption, Ca II H andK emission, X-ray luminosity, and stellar kinematic population. With theexception of the very unusual pre-main-sequence star system HD 98800,all the late-type Vega-like stars are the same age as the Hyades cluster(600-800 Myr) or older.
| 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
| Photometric Measurements of the Fields of More than 700 Nearby Stars
In preparation for optical/IR interferometric searches for substellarcompanions of nearby stars, we undertook to characterize the fields ofall nearby stars visible from the Northern Hemisphere to determinesuitable companions for interferometric phase referencing. Because theKeck Interferometer in particular will be able to phase-reference oncompanions within the isoplanatic patch (30") to about 17th magnitude atK, we took images at V, r, and i that were deep enough to determine iffield stars were present to this magnitude around nearby stars using aspot-coated CCD. We report on 733 fields containing 10,629 measurementsin up to three filters (Gunn i, r and Johnson V) of nearby stars down toabout 13th magnitude at V.
| The catalogue of nearby stars metallicities.
Not Available
| The general catalogue of trigonometric [stellar] paralaxes
Not Available
| Selection of standard stars for photometric observations with the 91-cm reflector at Okayama
Not Available
| Predicted infrared brightness of stars within 25 parsecs of the sun
Procedures are given for transforming selected optical data intoinfrared flux densities or irradiances. The results provide R, T(eff)blackbody approximations for about 2000 of the stars in Woolley et al.'sCatalog of Stars (1970) within 25 pc of the sun, and additional whitedwarfs, with infrared flux densities predicted for them at ninewavelengths from 2.2 to 101 microns including the Infrared AstronomySatellite bands.
| UBV Photometry of 500 Southern Stars [erratum: 1973MNSSA..32...48C]
Not Available
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Гидра |
| Прямое восхождение: | 08h12m52.02s |
| Склонение: | -07°12'16.7" |
| Видимая звёздная величина: | 7.914 |
| Расстояние: | 90.827 парсек |
| Собственное движение RA: | 150.5 |
| Собственное движение Dec: | -98 |
| B-T magnitude: | 9.036 |
| V-T magnitude: | 8.007 |
Каталоги и обозначения:
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