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Late A-type stars: new Strömgren photometric calibrations of absolute magnitudes from HIPPARCOS
Hipparcos trigonometric parallaxes have been used to derive aphotometric absolute magnitude calibration of main-sequence late A-typestars in terms of Strömgren photometric indices - accounting fortemperature, evolution and metallicity effects - and projectedequatorial rotational velocities. The derived calibrations are valid formain-sequence normal A3-A9 and metallic Am stars, showing residuals of0.22 and 0.20 magnitudes, respectively. One of the fitting methods used(BCES) allows the derivation of the observational ZAMS in this spectralrange, showing an excellent accordance with theoretical evolutionarymodels. The evolutionary state of the Am stars is also discussed.Table~A1 is only available in electronic form from CDS via anonymous ftp130.79.128.5, and by e-mail: request to cesca@am.ub.es
| UVBY beta photometry of peculiar B and A stars, discovered at Abastumani
Stromgren uvby photometry for 70 peculiar Bp, Ap, or Am type stars ispresented. The model grid of Relyea and Kurucz (1978) is used to obtaineffective temperatures and log g values, confirming the dwarf-nature ofAm stars. Good agreement is found between effective temperatures andequivalent spectral classes derived from the (b-y)0 values, although theA4-A5 stars in this sample may be cooler than normal stars ofluminosity-class III-V in this spectral range.
| Classification spectrale d'etoiles AP et Am.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975A&AS...21...25F&db_key=AST
| Multicolor photometry of metallic-line stars. III. A photometric catalogue
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974RMxAA...1..175M&db_key=AST
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Herkul |
| Sað Açýklýk: | 17h41m31.67s |
| Yükselim: | +46°19'23.7" |
| Görünürdeki Parlaklýk: | 8.885 |
| Uzaklýk: | 208.333 parsek |
| özdevim Sað Açýklýk: | -4.5 |
| özdevim Yükselim: | -5.8 |
| B-T magnitude: | 9.259 |
| V-T magnitude: | 8.916 |
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