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Chemically Peculiar/Magnetic Stars and the D a photometry. Hans Michael Maitzen, Ernst Paunzen Institute for Astronomy, University of Vienna. Properties. Strong magnetic field implies chemical peculiarity Spectral range: B0 - F2 Low rotational velocities Variability - PowerPoint PPT Presentation
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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
Classification resolution spectroscopy
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
An example
Corona Borealis
a Photometry a = g2 - [(g1 + y)/2]
a = a(star) - a0
a Photometry of open clusters
a Photometry in the LMC - NGC 1866
Galactic ejection path of HIP 60350
The graph shows the way of the ejected B4V star HIP 60350
Path from the lower left (close to NGC 3603) to the upper right in the vicinity of the Sun
Present LSR velocity 417 km s-1