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Pulkovo compilation of radial velocities for 35495 stars in a common system.
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| Optical follow-up of ROSAT discovered candidate members of the open cluster Coma Berenices
We have carried out an optical follow-up of twelve ROSAT discoveredcandidate members of the Coma Berenices open cluster. VRI photometry andlow resolution ( ~ 3 Å) spectroscopy in the range 3800-7000Åwere performed to obtain colour-magnitude diagrams, propermotions, spectral types, chromospheric activity levels and radialvelocities that allow us to establish whether or not these candidatesare reliable cluster members. Only four of these objects show opticalphotometry marginally compatible with the main sequence delineated byknown cluster stars. They also exhibit spectral types corresponding tolate-K and early-M, and radial velocities which are not inconsistentwith membership in Coma Berenices. The proper motions of thesecandidates are, however, very high and incompatible with the small valueassociated with the cluster. Thus, none of the ROSAT candidates can beconsidered members of Coma Berenices. This result tends to favour thehypothesis that the mass of the cluster and its average mass density arelower than what is required for stability, allowing the clusterdissolution by the escape of the less massive stars. We discuss theprobable nature of these objects on the basis of the availableinformation. From our radial velocity observations we infer that five ofthem could be formed by multiple stars. In particular, we havediscovered one W-type W UMa contact binary system (K6 spectral type)which is, in addition, a visual companion to a cooler star. Based onobservations made with the Isaac Newton telescope, operated on theisland of La Palma by the Isaac Newton Group in the Spanish Observatoriodel Roque de los Muchachos, with the IAC80 telescope and with theEuropean Space Agency OGS telescope operated on the island of Tenerifeby the Instituto de Astrofísica de Canarias in the SpanishObservatorio del Teide of the Instituto de Astrofísica deCanarias.
| The space distribution of late type stars in a North galactic pole region.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1962AJ.....67...37U&db_key=AST
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Membro dei seguenti gruppi:
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Osservazione e dati astrometrici
| Costellazione: | Orsa Maggiore |
| Ascensione retta: | 11h41m32.53s |
| Declinazione: | +42°53'05.5" |
| Magnitudine apparente: | 9.188 |
| Moto proprio RA: | 26.7 |
| Moto proprio Dec: | 15.8 |
| B-T magnitude: | 10.2 |
| V-T magnitude: | 9.272 |
Cataloghi e designazioni:
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