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261.
262.
Alisher S. Hojaev 《Journal of Astrophysics and Astronomy》2005,26(2-3):293-299
Preliminary results on observations of open clusters are presented. The project has been initiated in the framework of the
Uzbek-Taiwan and Taiwan-Baltic collaboration, mainly to upgrade and make use of facilities at Maidanak Observatory. We present
detailed, multiwavelength studies of the young cluster NGC 6823 and the associated complex nebulosity, to diagnose the young
stellar population and star formation history in the region. In addition, 7 compact open clusters have been monitored for
stellar variability. We show how observations like these could feasibly be used to look for exoplanet transit events. We also
expect to join the Whole-Earth Telescope effort in future campaigns for asteroseismology. 相似文献
263.
B. Fuchs D. Breitschwerdt M. A. de Avillez C. Dettbarn C. Flynn 《Monthly notices of the Royal Astronomical Society》2006,373(3):993-1003
We present a new unbiased search and analysis of all B stars in the solar neighbourhood (within a volume of 400 pc diameter) using the Arivel data base to track down the remains of the OB associations, which hosted the supernovae (SNe) responsible for the Local Bubble (LB) in the interstellar gas. We find after careful dereddening and by comparison with theoretical isochrones, that besides the Upper Scorpius the Upper Centaurus Lupus and Lower Centaurus Crux subgroups are the youngest stellar associations in the solar neighbourhood with ages of 20–30 Myr, in agreement with previous work. In search for the 'smoking gun' of the origin of the LB, we have traced the paths of the associations back into the past and found that they entered the present bubble region 10–15 Myr ago. We argue that the LB began to form then and estimate that 14–20 SNe have gone off since. It is shown that the implied energy input is sufficient to excavate a bubble of the presently observed size. 相似文献
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M. Patel R. D. Oudmaijer J. S. Vink J. C. Mottram B. Davies 《Monthly notices of the Royal Astronomical Society》2006,373(4):1641-1647
We aim to characterize the current status of knowledge on the accuracy of open-cluster parameters such as the age, reddening and distance. These astrophysical quantities are often used to study the global characteristics of the Milky Way down to the very local stellar phenomena. In general, the errors of these quantities are neglected or set to some kind of heuristic standard value. We attempt to give some realistic estimates for the accuracy of available cluster parameters by using the independently derived values published in the literature. In total, 6437 individual estimates for 395 open clusters were used in our statistical analysis. We discuss the error sources depending on theoretical as well as observational methods and compare our results with those parameters listed in the widely used catalogue by Dias et al. In addition, we establish a list of 72 open clusters with the most accurate known parameters which should serve as a standard table in the future for testing isochrones and stellar models. 相似文献
268.
Giovanni Carraro Brian Chaboyer James Perencevich 《Monthly notices of the Royal Astronomical Society》2006,365(3):867-873
The first charge-coupled device UBV ( RI )C photometric study in the area of the doubtful open cluster NGC 2129 is presented. Photometry of a field offset 15 arcmin northwards is also provided, to probe the Galactic disc population towards the cluster. Using star counts, proper motions from the UCAC2 catalogue, colour–magnitude and colour–colour diagrams, we demonstrate that NGC 2129 is a young open cluster. The cluster radius is 2.5 arcmin, and across this region we find evidence of significant differential reddening, although the reddening law seems to be normal towards its direction. Updated estimates of the cluster fundamental parameters are provided. The mean reddening is found to be E ( B − V ) = 0.80 ± 0.08 and the distance modulus is ( m − M )0 = 11.70 ± 0.30 . Hence, NGC 2129 is located at 2.2 ± 0.2 kpc from the Sun inside the Local spiral arm. The age derived from 37 photometrically selected members is estimated to be approximately 10 Myr. These stars are used to provide new estimates of the cluster absolute proper-motion components. 相似文献
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S. Britzen A. Witzel T. P. Krichbaum T. Beckert R. M. Campbell C. Schalinski J. Campbell 《Monthly notices of the Royal Astronomical Society》2005,362(3):966-974
We present deep CCD BVI photometry of the distant, old open cluster Berkeley 22, covering from the red giant branch (RGB) to about six magnitudes below the main-sequence (MS) turn-off. Using the synthetic colour–magnitude diagram method with three different types of stellar evolutionary tracks, we estimate values and theoretical uncertainties of the distance modulus ( m − M )0 , reddening E ( B − V ), age τ and approximate metallicity. The best fit to the data is obtained for 13.8 ≤ ( m − M )0 ≤ 14.1, 0.64 ≤ E ( B − V ) ≤ 0.65, 2.0 ≤τ≤ 2.5 Gyr (depending on the amount of overshooting from convective regions adopted in the stellar models) and solar metallicity. 相似文献