Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
X-Ray-Emitting Stars Identified from the ROSAT All-Sky Survey and the Sloan Digital Sky Survey
The ROSAT All-Sky Survey (RASS) was the first imaging X-ray survey ofthe entire sky. Combining the RASS Bright and Faint Source Catalogsyields an average of about three X-ray sources per square degree.However, while X-ray source counterparts are known to range from distantquasars to nearby M dwarfs, the RASS data alone are often insufficientto determine the nature of an X-ray source. As a result, large-scalefollow-up programs are required to construct samples of known X-rayemitters. We use optical data produced by the Sloan Digital Sky Survey(SDSS) to identify 709 stellar X-ray emitters cataloged in the RASS andfalling within the SDSS Data Release 1 footprint. Most of these arebright stars with coronal X-ray emission unsuitable for SDSSspectroscopy, which is designed for fainter objects (g > 15 [mag]).Instead, we use SDSS photometry, correlations with the Two Micron AllSky Survey and other catalogs, and spectroscopy from the Apache PointObservatory 3.5 m telescope to identify these stellar X-raycounterparts. Our sample of 707 X-ray-emitting F, G, K, and M stars isone of the largest X-ray-selected samples of such stars. We derivedistances to these stars using photometric parallax relationsappropriate for dwarfs on the main sequence, and use these distances tocalculate LX . We also identify a previously unknowncataclysmic variable (CV) as a RASS counterpart. Separately, we usecorrelations of the RASS and the SDSS spectroscopic catalogs of CVs andwhite dwarfs (WDs) to study the properties of these rarer X-ray-emittingstars. We examine the relationship between (fX /fg) and the equivalent width of the Hβ emission line for 46X-ray-emitting CVs and discuss tentative classifications for a subsetbased on these quantities. We identify 17 new X-ray-emitting DA(hydrogen) WDs, of which three are newly identified WDs. We report onfollow-up observations of three candidate cool X-ray-emitting WDs (oneDA and two DB (helium) WDs); we have not confirmed X-ray emission fromthese WDs.Includes observations obtained with the Apache Point Observatory 3.5 mtelescope, which is owned and operated by the Astrophysical ResearchConsortium.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of 14 000 F and G dwarfs
We present and discuss new determinations of metallicity, rotation, age,kinematics, and Galactic orbits for a complete, magnitude-limited, andkinematically unbiased sample of 16 682 nearby F and G dwarf stars. Our63 000 new, accurate radial-velocity observations for nearly 13 500stars allow identification of most of the binary stars in the sampleand, together with published uvbyβ photometry, Hipparcosparallaxes, Tycho-2 proper motions, and a few earlier radial velocities,complete the kinematic information for 14 139 stars. These high-qualityvelocity data are supplemented by effective temperatures andmetallicities newly derived from recent and/or revised calibrations. Theremaining stars either lack Hipparcos data or have fast rotation. Amajor effort has been devoted to the determination of new isochrone agesfor all stars for which this is possible. Particular attention has beengiven to a realistic treatment of statistical biases and errorestimates, as standard techniques tend to underestimate these effectsand introduce spurious features in the age distributions. Our ages agreewell with those by Edvardsson et al. (\cite{edv93}), despite severalastrophysical and computational improvements since then. We demonstrate,however, how strong observational and theoretical biases cause thedistribution of the observed ages to be very different from that of thetrue age distribution of the sample. Among the many basic relations ofthe Galactic disk that can be reinvestigated from the data presentedhere, we revisit the metallicity distribution of the G dwarfs and theage-metallicity, age-velocity, and metallicity-velocity relations of theSolar neighbourhood. Our first results confirm the lack of metal-poor Gdwarfs relative to closed-box model predictions (the ``G dwarfproblem''), the existence of radial metallicity gradients in the disk,the small change in mean metallicity of the thin disk since itsformation and the substantial scatter in metallicity at all ages, andthe continuing kinematic heating of the thin disk with an efficiencyconsistent with that expected for a combination of spiral arms and giantmolecular clouds. Distinct features in the distribution of the Vcomponent of the space motion are extended in age and metallicity,corresponding to the effects of stochastic spiral waves rather thanclassical moving groups, and may complicate the identification ofthick-disk stars from kinematic criteria. More advanced analyses of thisrich material will require careful simulations of the selection criteriafor the sample and the distribution of observational errors.Based on observations made with the Danish 1.5-m telescope at ESO, LaSilla, Chile, and with the Swiss 1-m telescope at Observatoire deHaute-Provence, France.Complete Tables 1 and 2 are only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/989
| Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| Double Star Measurements Made at Nice
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..102..643M&db_key=AST
| Relative motions of 17 visual double stars
The relative motions of 17 visual stars are studied; the data cited indeveloping the equations of relative motion are often from observationsmade 50 or more years ago. The results are compared with the data fromSAO, IDS and AGK catalogs.
| Radial Velocities, Spectral Types, and Luminosity Classes of 820 Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1950ApJ...112...48M&db_key=AST
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
| Созвездие: | Дракон |
| Прямое восхождение: | 11h36m14.70s |
| Склонение: | +66°20'42.8" |
| Видимая звёздная величина: | 7.909 |
| Расстояние: | 126.743 парсек |
| Собственное движение RA: | 31.3 |
| Собственное движение Dec: | 42.4 |
| B-T magnitude: | 8.427 |
| V-T magnitude: | 7.952 |
Каталоги и обозначения:
|
