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Seven-Color Photometry of the Open Cluster NGC 1647 Area
The area of the open cluster NGC 1647 in Taurus is investigated by CCDphotometry in the Vilnius seven-color system. Magnitudes and colorindices are determined for 433 stars down to V = 15.0 mag in the 45arcmin diameter area. For 252 of them photometric spectral andluminosity classes, interstellar reddenings, extinctions and distancesare obtained. According to the CDS WEBDA database, 89 of them have ahigh cluster membership probability. Their mean distance from the Sunis 555±74 pc, excluding four stars which seem to be field stars.The main sequence starts at spectral class B7 V which corresponds to acluster age of about 150 million years. Cluster members show adifferential interstellar extinction ranging from 0.8 to 1.8 mag. Themean extinction of the cluster stars is 1.12±0.25 mag.Interstellar extinction in the area is dominated by the Taurus darkcloud complex at 160 pc. Color excesses of individual stars correlatewell with the 100 μm dust thermal emission intensity. The clustershape is investigated by counting stars down to K=15.6 mag and is foundto be elongated in the direction roughly perpendicular to the Milky Way,with the flattening 0.4.
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| Galactic clusters with associated Cepheid variables. III - NGC 1647 and SZ Tauri
Observational data and analysis are used to argue that the Cepheid Z Tauis an outlying member of the open cluster NGC 1647. The spatialcoincidence of the Cepheid with the cluster corona, as well ascoincidences in radial velocity, proper motion, and age with clustermembers, present a convincing case for cluster membership, which is alsosupported by independent estimates for the mean radius of SZ Tau. Theevidence presented by the derived luminosity of the Cepheid and itslight curve strongly indicates that SZ Tau is pulsating in the firstovertone, rather than fundamental, mode.
| Photoelectric observations of lunar occultations. XIII
Occultation observations made with the 0.76 m reflector at McDonaldObservatory are presented, for 319 events occurring between Jan. 15,1981 and Feb. 7, 1982. One table reports timings, and a second recordsobservations of 16 double stars, in particular, Nu Gem observationsreveal that the two close components are similar in color. This allowsan estimation of individual visible magnitudes (near 4.60 and 5.32)suggesting that the secondary is a late B-type main-sequence star. SAO158929 observations reveal systematic differences in angular diametervalues. Of the 16 observed double stars, 9 appear to be new discoveries,including SAO 93067, SAO 94595, and SAO 98770. A third table gives fullydarkened angular diameters for the stars SAO 158929, SAO 77516 Y Tau,and SAO 119035 Nu Vir.
| Red indices in galactic clusters
Not Available
| An investigation of color excess in galactic star clusters
Not Available
| Effective wavelengths of 184 stars in the cluster NGC 1647.
Not Available
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Pozíciós és asztrometriai adatok
| Csillagkép: | Bika |
| Rektaszcenzió: | 04h45m54.25s |
| Deklináció: | +18°56'59.1" |
| Vizuális fényesség: | 9.624 |
| RA sajátmozgás: | -2.7 |
| Dec sajátmozgás: | -3.6 |
| B-T magnitude: | 9.936 |
| V-T magnitude: | 9.65 |
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