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Astron. Astrophys. 343, 446-454 (1999)

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Late A-type stars: new Strömgren photometric calibrations of absolute magnitudes from Hipparcos *

A. Domingo and F. Figueras

Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Spain

Received 7 August 1998 / Accepted 6 November 1998


Hipparcos trigonometric parallaxes have been used to derive a photometric absolute magnitude calibration of main-sequence late A-type stars in terms of Strömgren photometric indices - accounting for temperature, evolution and metallicity effects - and projected equatorial rotational velocities. The derived calibrations are valid for main-sequence normal A3-A9 and metallic Am stars, showing residuals of 0.22 and 0.20 magnitudes, respectively. One of the fitting methods used (BCES) allows the derivation of the observational ZAMS in this spectral range, showing an excellent accordance with theoretical evolutionary models. The evolutionary state of the Am stars is also discussed.

Key words: stars: chemically peculiar – stars: distances – stars: early-type – stars: fundamental parameters – stars: Hertzsprung – Russel (HR) and C-M diagrams

* Table A1 is only available in electronic form from CDS via anonymous ftp, (ftp://cdsarc.u-strasbg.fr/pub/cats/J/A+A/343/446) and by e-mail: request to cesca@am.ub.es

Send offprint requests to: F. Figueras

Correspondence to: cesca@am.ub.es

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© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999