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Chemically Peculiar/Magnetic Stars and the D a photometry

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

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Chemically Peculiar/Magnetic Stars and the D a photometry

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  1. Chemically Peculiar/Magnetic Stars and the Da photometry Hans Michael Maitzen, Ernst Paunzen Institute for Astronomy, University of Vienna

  2. Properties • Strong magnetic field implies chemical peculiarity • Spectral range: B0 - F2 • Low rotational velocities • Variability • about 5% of all stars in this spectral range

  3. Notation according to Preston

  4. History facts I • 1897: Detection by Antonia Maury • 1914: Guthnik and Prager observe for the first time the light curve of the prototype star a2 CVn • 1933: Morgan finds correlation between temperature and chemical composition • 1947: Babcock discovers magnetic fields • 1950: Stibbs develops the Oblique Rotator Theory

  5. 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 Da observations published • 2001: First chemically peculiar stars detected in the LMC by Da photometry

  6. Classification resolution spectroscopy

  7. Origin of magnetic fields • Dynamo Theory: Rotation produces self induction • Theory of the fossil magnetic field: interstellar origin pre-main sequence evolution

  8. Characteristics of magnetic fields • Dipole • Quadrupole • Rotational axis ¹ Magnetic axis • 300 G £ Heff£ 40 kG • Sun: 10 G (up to 4000 G) • Jupiter: 5 - 20 G • Earth: 0.3 - 0.6 G

  9. An example

  10. b Corona Borealis

  11. Da Photometry • a = g2 - [(g1 + y)/2] • Da = a(star) - a0

  12. Da Photometry of open clusters

  13. Da Photometry in the LMC - NGC 1866

  14. 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

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