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Chemically Peculiar/Magnetic Stars and the a photometry
Hans Michael Maitzen, Ernst Paunzen
Institute for Astronomy, University of Vienna
Properties
Strong magnetic field implies chemical peculiarity
Spectral range: B0 - F2Low rotational velocitiesVariability about 5% of all stars in this spectral range
Notation according to Preston
Group Designation Magnetic field Spectral type
CP1 Am no B9 – F4
CP2 Ap Si, Cr, Eu, Sr strong B6 – F2
CP3 Ap Hg, Mn weak B5 – A0
CP4 He-weak weak/strong B2 – B8
He-strong weak/strong B0 – B4
Bootis no B9 – F2
History facts I
1897: Detection by Antonia Maury 1914: Guthnik and Prager observe for the first
time the light curve of the prototype star 2 CVn
1933: Morgan finds correlation between temperature and chemical composition
1947: Babcock discovers magnetic fields 1950: Stibbs develops the Oblique Rotator
Theory
History facts II 1958: Deutsch publishes the first abundance maps of the
surface for peculiar stars 1968: Kodaira discovers flux depressions at 4100Å, 5200Å
and 6300Å 1974: Preston introduces a new classification scheme for
peculiar stars which is still in use 1976: First a observations published 2001: First chemically peculiar stars detected in the LMC by
a photometry
Origin of magnetic fields
Dynamo Theory: Rotation produces self induction
Theory of the fossil magnetic field:interstellar origin
pre-main sequence evolution
Characteristics of magnetic fields
DipoleQuadrupoleRotational axis
agnetic axis
300 G Heff 40 kG
Sun: 10 G (up to 4000 G) Jupiter: 5 - 20 GEarth: 0.3 - 0.6 G