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151.
A. Castillo-Morales J. Jiménez-Vicente E. Mediavilla E. Battaner 《Monthly notices of the Royal Astronomical Society》2007,380(2):489-498
We analyse new integral-field spectroscopy of the inner region (central 2.5 kpc) of the spiral galaxy NGC 4321 to study the peculiar kinematics of this region. Fourier analysis of the velocity residuals obtained by subtracting an axisymmetric rotation model from the Hα velocity field indicates that the distortions are global features generated by an m = 2 perturbation of the gravitational potential which can be explained by the nuclear bar. This bar has been previously observed in the near-infrared but not in the optical continuum dominated by star formation. We detect the optical counterpart of this bar in the 2D distribution of the old stellar population (inferred from the equivalent width map of the stellar absorption lines). We apply the Tremaine–Weinberg method to the stellar velocity field to calculate the pattern speed of the inner bar, obtaining a value of Ωb = 160 ± 70 km s−1 kpc−1 . This value is considerably larger than the one obtained when a simple bar model is considered. However, the uncertainties in the pattern speed determination prevent us from giving support to alternative scenarios. 相似文献
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NGC 663 is a young, moderately rich open cluster, known to contain one of the largest fractions of Be stars among all galactic clusters. In this work we present CCD u v by β photometry for stars in its central area. We have used these data to obtain the main cluster physical parameters. We find that the reddening is highly variable, with values ranging from E ( b − y ) = 0.639 ± 0.032 in the central part to E ( b − y ) = 0.555 ± 0.038 in the south-east. The distance modulus is found to be 11.6 ± 0.1 mag (2.1 kpc) and the age log t = 7.4 ± 0.1 yr (25+7 −5 Myr) . The age obtained is consistent with the interpretation of the Be phenomenon as an evolutionary effect. 相似文献
154.
A. Pastorello P. A. Mazzali G. Pignata S. Benetti E. Cappellaro A. V. Filippenko W. Li W. P. S. Meikle A. A. Arkharov G. Blanc F. Bufano A. Derekas M. Dolci N. Elias-Rosa R. J. Foley M. Ganeshalingam A. Harutyunyan L. L. Kiss R. Kotak V. M. Larionov J. R. Lucey N. Napoleone H. Navasardyan F. Patat J. Rich S. D. Ryder M. Salvo B. P. Schmidt V. Stanishev P. Székely S. Taubenberger S. Temporin M. Turatto W. Hillebrandt 《Monthly notices of the Royal Astronomical Society》2007,377(4):1531-1552
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H. Bruntt D. Stello J. C. Suárez T. Arentoft T. R. Bedding M. Y. Bouzid Z. Csubry T. H. Dall Z. E. Dind S. Frandsen R. L. Gilliland A. P. Jacob H. R. Jensen Y. B. Kang S.-L. Kim L. L. Kiss H. Kjeldsen J.-R. Koo J.-A. Lee C.-U. Lee J. Nuspl C. Sterken R. Szabó 《Monthly notices of the Royal Astronomical Society》2007,378(4):1371-1384
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