An empirical temperature calibration for the Δa photometric system I. The B-type stars
- Autor(en)
- Ernst Paunzen, Anneliese Schnell, Hans Michael Maitzen
- Abstrakt
We establish an empirical effective temperature calibration of main sequence, luminosity class V to III B-type stars for the ?a photometric system which was originally developed to detect magnetic chemically peculiar objects of the upper main sequence (early B-type to early F-type) at 5200 A°. However, this system provides the index (g1 - y) which shows an excellent correlation with (B - V) as well as (b- y) and can be used as an indicator of the effective temperature. This is supplemented by a very accurate color-magnitude diagram, y or V versus (g1 - y), which can be used, for example, to determine the reddening, distance and age of an open cluster. This makes the ?a photometric system an excellent tool to investigate the Hertzsprung-Russell-Diagram (HRD) in more detail. Using the reddening-free parameters and already established calibrations within the Strošmgren uvbyß, Geneva 7-color and Johnson UBV systems, a polynomial fit of third degree for the averaged effective temperatures to the individual (g1 - y)0 values was derived. For this purpose, data from the literature as well as new observations were taken resulting in 225 suitable bright normal B-type objects. The statistical mean of the error for this sample is 238 K which is sufficient to investigate the HRD of distant galactic open clusters as well as extragalactic aggregates in the future. Œ ESO 2005.
- Organisation(en)
- Zentraler Informatikdienst, Institut für Astrophysik
- Journal
- Astronomy & Astrophysics
- Band
- 444
- Seiten
- 941-946
- Anzahl der Seiten
- 6
- ISSN
- 0004-6361
- DOI
- https://doi.org/10.1051/0004-6361:20053546
- Publikationsdatum
- 2005
- Peer-reviewed
- Ja
- ÖFOS 2012
- 103003 Astronomie
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/eb834131-2b81-402e-8db1-6f21d1e58125