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Lacerta OB1 Revisited
This investigation utilizes precise uvby? photometry and therecently recalculated Hipparcos data to provide an improved homogeneousdistance scale for the apparent groups of young stars in Lacerta. Allexisting uvby? photometry for stars earlier than A0-type in a20°×20° field centered at l=100°, b=-15° iscollated and the individual stellar distances and color excesses areobtained. The association Lac OB1 is reliably identified as a verycompact young group of 12 bright stars at an average distance of520±20(s.e.) pc. The available radial velocity and proper motionmeasurements strongly support the impression that the group is real. Thestars in the northeast part of Lacerta seem not to represent a physicalgroup, but rather a layer of field stars spread between 140 and 400 pcand extending farther than that toward l˜104°. An estimate of678±50(s.e.) pc of the distance to the open cluster NGC 7243 isobtained based on the brightest cluster members. The calculateddistances are based on a well-tested procedure, and thus represent aclarification over the range of distance existing in the literature forthe bright stars in the Lacerta field. Although a better agreement isnow evident between the photometric distances and the recalculatedHipparcos parallaxes in comparison to the original Hipparcos data,discrepancies still exist for this particular field.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
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| Memberships and CM diagrams of the open cluster NGC 7243
The results of astrometric and photometric investigations of the opencluster NGC 7243 are presented. Proper motions of 2165 stars withroot-mean-square error of 1.1;mas yr-1 were obtained by meansof PDS scanning of astrometric plates covering 97 years. A total of 211cluster members down to V=15.5;mag have been identified. V and Bmagnitudes have been determined for 2118 and 2110 stars respectively.Estimations of mass (348 Msun <=M_TOT <=522Msun), age (t=2.5x 108 yr), distance (r=698 pc)and reddening (EB-V=0.24) of the cluster NGC 7243 have beenmade.Table 8 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) orhttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/401/531
| 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
| Photoelectric search for CP2-stars in open clusters. XII - Alpha Persei, Praesepe and NGC 7243
Observations of 95 stars in the open clusters Alpha Persei, Praesepe,and NGC 7243 have been performed by Delta-a photometry in order tosearch for the presence of the 5200-A feature of CP2 (or CP4) stars.Although peculiarity has been claimed for half a dozen stars in AlphaPersei, the photometry detects only the CP4 star (= He-weak) HL 985among the cluster members. The behavior of 3 Be/shell stars (HL 861,1164, 904) concerning the 5200-A feature is discussed. Praesepe, by farthe oldest cluster in the survey program, presents a very new andspecial case: 3 stars, previously classified as Am have Delta-a valuesaround 0.020 mag, i.e., they exhibit photometric peculiarity likeCP2-stars. Such values are incompatible with preceding results for fieldand cluster Am-stars (= CP3). These objects deserve further attentionboth photometrically and spectroscopically. NGC 7243 exhibits anoutstanding high frequency of CP2-stars; two certain Delta a-peculiarstars have been found: L 370, already known as peculiar, and the newlyidentified L 114. Two stars are near the detection level: L 58 and 121.According to Geneva photometry, L 487 is markedly peculiar.
| Prediction of spectral classification from photometric observations - Application of the UVBY beta photometry and the MK spectra classification. II - General case
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&A....85...93M&db_key=AST
| Prediction of spectral classification from photometric observations-application to the UVBY beta photometry and the MK spectral classification. I - Prediction assuming a luminosity class
An algorithm based on multiple stepwise and isotonic regressions isdeveloped for the prediction of spectral classification from photometricdata. The prediction assumes a luminosity class with reference touvbybeta photometry and the MK spectral classification. The precisionattained is about 90 percent and 80 percent probability of being withinone spectral subtype respectively for luminosity groups I and V and forluminosity groups III and IV. A list of stars for which discrepanciesappear between photometry and spectral classification is given.
| HY equivalent widths in the open cluster NGC 7243
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..376H&db_key=AST
| A spectroscopic and photometric investigation of NGC 7243.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..110H&db_key=AST
| Untersuchungen der offenen Sternhaufen NGC 7092 (M 39), NGC 7209, und NCG [sic] 7243
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Observation and Astrometry data
| Constellation: | Σαύρα |
| Right ascension: | 22h14m27.23s |
| Declination: | +49°52'17.7" |
| Apparent magnitude: | 8.513 |
| Distance: | 1515.152 parsecs |
| Proper motion RA: | -0.2 |
| Proper motion Dec: | -2.5 |
| B-T magnitude: | 8.602 |
| V-T magnitude: | 8.521 |
Catalogs and designations:
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