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HUNTING THE RG DESCENDANTS OF Ap STARS Michel Aurière Renada Konstantinova-Antova

HUNTING THE RG DESCENDANTS OF Ap STARS Michel Aurière Renada Konstantinova-Antova Corinne Charbonnel Sophie Van Eck Pascal Petit Svetla Tsvetkova et al. Ap stars Magnetic Ap/Bp stars Slow rotators Chemically peculiar Strong large scale MF (of fossil origin ?)

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HUNTING THE RG DESCENDANTS OF Ap STARS Michel Aurière Renada Konstantinova-Antova

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  1. HUNTING THE RG DESCENDANTS OF Ap STARS Michel Aurière Renada Konstantinova-Antova Corinne Charbonnel Sophie Van Eck Pascal Petit Svetla Tsvetkova et al.

  2. Ap stars Magnetic Ap/Bp stars Slow rotators Chemically peculiar Strong large scale MF (of fossil origin ?) Progenitors of magnetic white dwarves ? About 2-5 % of A-type stars A dozen of Ap star descendants inside D<100 pc from sun ? Could be outstanding magnetically active slow rotators

  3. THE HISTORICAL CASE EK ERI = HR1362 (Stepien 1993) - G8 III-IV - Very magnetically active in X-rays (~1030 ergs/s), CaII H&K in emission, photometric variability... - Slow rotator: Prot = 308.8 d - Suspected to be an Ap-star descendant - Rossby number ~ 2

  4. EKERI: V, V-I PHOTOMETRY(Dall et al. 2010)‏

  5. EKERI: LONGITUDINAL MAGNETIC FIELD

  6. EK ERI :Variations of Bl with phase

  7. EK ERI ZDI MAP A Dominant Magnetic Dipole

  8. EK ERI : A DOMINANT MAGNETIC DIPOLE i = 60° beta = 45° Bmax = 200 G Axisymetry: 79 % Poloidal: 98% Dipolar: 90% Quadripolar : 6% magnetic/photometric spot = negative pole of the dipole = remnant from Ap-star dipole?

  9. 14 CET : The Outstanding F Star F5IV Studied during 25 years by the HK survey (M cycle of 5 y?) Vsini < 4-5 km/s Zeeman detected : Bl~ -30 G Known magnetic F * : Fp or later than F7

  10. 14 CETEvolutionary models of Charbonnel and Lagarde 2010

  11. 14 CET : Be abundance

  12. 14 CET : Vrot

  13. VARIATIONS OF Bl OF 14 CET July-November 2011

  14. STRENGTH OF MF VERSUS Prot

  15. Beta Ceti K0III M ~ 3M_sun During 1st DUP Activity of a star of Prot about 50-60 d Prot ~ 120d

  16. Beta Ceti : Bl variations 2010-2011(Tsvetkova et al. 2012)

  17. Beta Ceti Prot=128 dTsvetkova et al. 20122010-2011 seasons

  18. Beta Ceti : ZDI MAP(Tsvetkova et al. 2012) Prot = 128 d No Diff. Rot. i = 42° Pol. at 95% Dip. 62% Axi : 62% Bmean = 12 G

  19. Ap STAR DESCENDANTSPRESENT STATUSOF OBSERVATIONS - CP wipped out - 3 stars with outstanding MF (2 with polo. topology) -  Other active « slow rotators » have MF strength coherent with Prot (look to their MF topology) TO LOOK TO RG WITH VERY WEAK MF AND VERY LONG PERIODS

  20. HISTOGRAM OF Prot

  21. POLLUX : HD 62509 - K0 III - Pvrad = 589.64 d : hosted planet? - Weak X-ray luminosity (solar level)‏ - Rossby number ~ > 2 ?

  22. POLLUX: VARIATIONS OF RV AND Bl

  23. THE MODELISATION SIDE TO STUDY THE INTERACTION OF : - A RIGID MAGNETIC FIELD - CONVECTION DONE MAINLY IN THE SOLAR CASE EVOLVING Ap STARS = EXCELLENT LABORATORY  ? !

  24. INTERACTION BETWEEN CONVECTION AND MFCattaneo et al. 2003

  25. SUN + FOSSIL MFStrugarek et al. 2011 Base of the CE : 0.72 R_sun Dipolar fossil MF buried deep in the radiative interior. The dipolar fossil MF spreads into the CE !

  26. FUTURE WORK - TO STUDY THE ZDI TOPOLOGY OF SLOW ROTATORS - STABLE RV VARIATIONS VERSUS PLANETS/STABLE MF TOPOLOGY - MODELING EVOLUTION OF SLOW ROTATORS WITH MAGNETIC BRAKING - MODELING OF A DIPOLE /CONVECTION INTERACTION

  27. POLLUX : DETECTION OF THE MAGNETIC FIELD

  28. EK ERI: HRD + EVOLUTIONARY MODELS (of Charbonnel and Lagarde 2010)‏

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