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Interstellar absorption lines toward Cep OB4
An analysis of optical echelle spectra towards nine stars in the Cep OB4association is presented. Interstellar absorption lines which arise inthe (1, 0) and (2, 0) bands of the CN A 2Π - X2Σ+ red system towards BD+66o1661, BD+66o 1674, and BD+66o 1675 are used toinfer accurate CN column densities N(CN). A comparison with earliermeasurements in the CN violet system allows to infer a CN Doppler bparameter of b(CN) = 1.2{-}2.4 km s-1. Molecular carbonabsorption lines which arise in the (1, 0), (2, 0) and (3, 0) bands ofthe C2 A1Πu -X1Σg+ Phillips system is used toinfer gaskinetic temperatures of 35±10 K and densities of n = 700± 200 cm-3 towards BD+66o 1661 andBD+66o 1675, and a temperature of 60±10 K and adensity of 800 ± 400 cm-3 towards BD+66o1674. The R(1) line of the (0, 0) band of the CH A2Δ -X2Π system is detected towards 6 stars. A tightcorrelation exists between N(C2) and N(CH). N(CN) increaseswith N(CH) and with N(C2). Interstellar CH+ ismarginally detected towards four stars. Inferred CH+ columndensities are significantly lower than towards other lines of sight withsimilar reddening. The velocity structure towards Cep OB4 and thechemical abundances suggest that CN, C2, CH, andCH+ are formed in quiescent material. A previous suggestionthat the molecules form in a photon-dominated region close to the starsis not supported by the observations.Based on observations collected at the Centro Astronómico HispanoAlemán (CAHA) at Calar Alto, operated jointly by the Max-PlanckInstitut für Astronomie and the Instituto de Astrofisica deAndalucia (CSIC).
| Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 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
| 21-cm observations of the CEP IV star-formation region
The Cep IV star-formation region has been mapped at 21 cm. The resultingH I distribution indicates that the available gas forms a broken ringcoincident with the optical nebulosity. Comparison of this feature withother kinematic data for both stars and gas suggests that sequentialstar formation is an ongoing process in this region.
| A Study of the Cepheus IV Association
Abstract image available at:http://adsabs.harvard.edu/abs/1968ApJS...16..275M
| The Cepheus IV Association.
Abstract image available at:http://adsabs.harvard.edu/abs/1965ApJ...141..660W
| A New O - B Association with an Unusual Reddening Effect.
Abstract image available at:http://adsabs.harvard.edu/abs/1959ApJ...130..482B
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Membro dei seguenti gruppi:
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Osservazione e dati astrometrici
| Costellazione: | Cefeo |
| Ascensione retta: | 23h57m36.65s |
| Declinazione: | +67°50'40.9" |
| Magnitudine apparente: | 10.129 |
| Moto proprio RA: | -1.7 |
| Moto proprio Dec: | -0.5 |
| B-T magnitude: | 10.841 |
| V-T magnitude: | 10.188 |
Cataloghi e designazioni:
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