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The international campaign "Photometry and Spectroscopy" of P Cygni. ASPA. Active Spectroscopy in Astronomy. Ernst Pollmann eMail: ernst-pollmann@t-online.de http://www.astrospectroscopy.de. 1. LBV - Characteristics

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ASPA

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  1. The international campaign "Photometry and Spectroscopy" of P Cygni ASPA Active Spectroscopy in Astronomy Ernst Pollmann eMail: ernst-pollmann@t-online.de http://www.astrospectroscopy.de

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  3. LBV - Characteristics • the most absolute massive and brightest supergiants withmore than 50 solar masses. They go through a very unstable phase with • strong variations in brigthness, in color and in their spectra • Gravity and pressure don´t keep balanced • The stars are unstable • They develop strong solar wind (10-3  solar masses per year) • Envelope around the star 2

  4. Photometric Variability Irregular brigthness variations Small rapid changes at about 0.01 mag in few hours Slow changes in the order of 2 mag in years to decades Occasional strong brightness outbursts AG Carinae R127 3

  5. Spectrum of P Cygni Hα HeI 6678 4

  6. Stellar wind of P Cygni to the observer 5

  7. Spectrum of P Cygni Hα HeI 6678 6

  8. Time behavior of the Hα-Emission (Equivalent width) 7

  9. Period Analysis Main period 1211 d Phase plot 8

  10. Photometric V-Variation and Variation of the Hα-EW (Markova) EW V 9

  11. V (photometr.) [mag] HαEW [Ǻ] V (photometr.) [mag] HαEW [Ǻ] 10

  12. The EW of a line is a measure of • the frequency of a element • the density of the gas • the temperatur of the layer in which it is developed • The Equivalent width indicates how much intensity an absorption line takes away from the continuum or an emission line adds to the continuum 11

  13. Intensität Kontinuum Wellenlänge [Å] 8000 7000 6000 5000 4000 3000 2000 Kontinuum 1000 13

  14. From the definition of EW and the relation between stellar magnitudes and continuum flux variations F2 / F1 = 10-0.4 (m2-m1) it follows the line flux is F = C * EW / 10 (0.4 Vphot) Here is C a constant factor. In practice, we correct EW with a simple division by 10(0.4*Vphot) Then the derived quantity is not the line flux in physical units, but a quantity proportional to the physical line flux, corrected for continuum variations 14 14

  15. Evidence of the independency of line flux F & V(photometr.) F = EW/10^(0.4*V) 15

  16. The intrinsic Hα-line flux from Nov./2008 until today 16

  17. Stellar wind of P Cygni to the observer 17

  18. The HeI6678-line in the spectrum of P Cygni Hα He6678-Region 18

  19. EW time behavior of the HeI 6678 absorption Variable mass loss rate ? 19

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