Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
Photoelectric radial velocities, Paper XVII The orbits of 30 spectroscopic binaries in the southern Clube Selected Areas
Three of the six southern Clube Areas that were mainly observed at theEuropean Southern Observatory and whose principal results are given inPaper XVI are marginally observable from Haute-Provence. Additionalmeasurements obtained on several observing runs there enabled orbits tobe determined (in most cases rather poorly, owing to the paucity ofdata) for 30 of the newly discovered spectroscopic-binary systems; theyare presented in this paper. One object, HD 33978, seems to be of suchsignificance that special efforts have been made, largely by Drs J.Andersen and H. Lindgren, to obtain additional radial-velocitymeasurements. That system is shown to be a double-lined binary with aperiod of only 10.67 d despite one of its components being a late-typegiant. The giant star has a projected rotational velocity of almost 40km s-1 it could be expected to exhibit RS CVn-typephotometric variations, which have not yet been observed, in addition tothe `ellipsoidal variation', discovered by Hipparcos, which occasionedits designation as VV Lep.
| Barium stars, galactic populations and evolution.
In this paper HIPPARCOS astrometric and kinematical data together withradial velocities from other sources are used to calibrate bothluminosity and kinematics parameters of Ba stars and to classify them.We confirm the results of our previous paper (where we used data fromthe HIPPARCOS Input Catalogue), and show that Ba stars are aninhomogeneous group. Five distinct classes have been found i.e. somehalo stars and four groups belonging to disk population: roughlysuper-giants, two groups of giants (one on the giant branch, the otherat the clump location) and dwarfs, with a few subgiants mixed with them.The confirmed or suspected duplicity, the variability and the range ofknown orbital periods found in each group give coherent resultssupporting the scenario for Ba stars that are not too highly massivebinary stars in any evolutionary stages but that all were previouslyenriched with Ba from a more evolved companion. The presence in thesample of a certain number of ``false'' Ba stars is confirmed. Theestimates of age and mass are compatible with models for stars with astrong Ba anomaly. The mild Ba stars with an estimated mass higher than3Msun_ may be either stars Ba enriched by themselves or``true'' Ba stars, which imposes new constraints on models.
| Absolute magnitudes and kinematics of barium stars.
The absolute magnitude of barium stars has been obtained fromkinematical data using a new algorithm based on the maximum-likelihoodprinciple. The method allows to separate a sample into groupscharacterized by different mean absolute magnitudes, kinematics andz-scale heights. It also takes into account, simultaneously, thecensorship in the sample and the errors on the observables. The methodhas been applied to a sample of 318 barium stars. Four groups have beendetected. Three of them show a kinematical behaviour corresponding todisk population stars. The fourth group contains stars with halokinematics. The luminosities of the disk population groups spread alarge range. The intrinsically brightest one (M_v_=-1.5mag,σ_M_=0.5mag) seems to be an inhomogeneous group containing bariumbinaries as well as AGB single stars. The most numerous group (about 150stars) has a mean absolute magnitude corresponding to stars in the redgiant branch (M_v_=0.9mag, σ_M_=0.8mag). The third group containsbarium dwarfs, the obtained mean absolute magnitude is characteristic ofstars on the main sequence or on the subgiant branch (M_v_=3.3mag,σ_M_=0.5mag). The obtained mean luminosities as well as thekinematical results are compatible with an evolutionary link betweenbarium dwarfs and classical barium giants. The highly luminous group isnot linked with these last two groups. More high-resolutionspectroscopic data will be necessary in order to better discriminatebetween barium and non-barium stars.
| SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
| UBV photometry of barium stars
Magnitudes in V and B-V and U-B colors observed by the 91-cm telescopeat Okayama are presented for 109 stars including both classical andmarginal barium stars. The two-color diagram shows a fair amount ofspread. This can be interpreted by interstellar reddening and variableamounts of line blocking effect. Both classical and marginal bariumstars form a fairly homogeneous group.
| Taxonomy of barium stars
Spectral classification, barium intensity, radial velocity, luminosity,and kinematical properties are determined for 389 barium stars byanalyzing image-tube spectra and photometric observation data. Diskkinematics for the stars are based on whether they are Ba weak or Bastrong. Weak barium stars in general have smaller velocity dispersions,brighter apparent magnitude, and lower luminosity than strong bariumstars. These characteristics are confirmed by solving for meanspectroscopic distances, z-scale height distances, and reduced propermotions.
| The frequency of wide binaries among the southern barium stars
All of the barium and marginal barium stars in the 1972 MacConnell,Frey, and Upgren list of such objects which are located south of thecelestial equator were examined for visual duplicity. Over 200 objectswere observed, and a total of six possible candidates for wide pairvisual binaries were found. Of these, four are most likely optical innature. These data suggest that the incidence of wide binaries amongbarium stars is of the order of 1%.
| E. W. Fick Observatory stellar radial velocity measurements. I - 1976-1984
Stellar radial velocity observations made with the large vacuumhigh-dispersion photoelectric radial velocity spectrometer at FickObservatory are reported. This includes nearly 2000 late-type starsobserved during 585 nights. Gradual modifications to this instrumentover its first eight years of operation have reduced the observationalerror for high-quality dip observations to + or - 0.8 km/s.
| The absolute magnitudes of the barium stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972AJ.....77..384M&db_key=AST
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
| Созвездие: | Эридан |
| Прямое восхождение: | 04h53m49.68s |
| Склонение: | -26°25'45.1" |
| Видимая звёздная величина: | 8.948 |
| Расстояние: | 370.37 парсек |
| Собственное движение RA: | -1.7 |
| Собственное движение Dec: | -12.8 |
| B-T magnitude: | 10.328 |
| V-T magnitude: | 9.062 |
Каталоги и обозначения:
|
