1. The Herbig Ae/Be stars: what we have learnt with ESPaDOnS E. Alecian, G.A. Wade, C. Catala, C. Folsom, J. Grunhut, J.-F. Donati, P. Petit, S. Bagnulo, S.C. Marsden, J.D. Landstreet, T. Böhm, J.-C. Bouret, J. Silvester Armagh Workshop 21/02/2008

2. E. Alecian Armagh Workshop 21/02/2008 Problematic 1 Origin of the magnetic fields in the Ap/Bp stars –Favoured hypothesis : the fossil field hypothesis  some of the intermediate mass PMS star should be magnetic  topology of B(PMS A/B) = topology B(Ap/Bp)  intensity B(PMS A/B) compatible with intensity B(Ap/Bp) (assuming the magnetic flux conservation) –Other hypothesis : the core dynamo

3. E. Alecian Armagh Workshop 21/02/2008 Problematic 2 Origin of the slow rotation of the Ap/Bp stars –Hypothesis 1 : magnetic braking during the PMS phase (Stepien & Lanstreet 2002)  magnetic PMS A/B stars should exist  PMS A/B stars should have a disk  Evolution of the rotation during the PMS phase –Hypothesis 2 : the magnetic field cannot survive in fast rotators (Lignières et al. 1996)  No magnetic fast rotators during the PMS phase

4. E. Alecian Armagh Workshop 21/02/2008 Strategy (1) Observation of the field Herbig Ae/Be stars –Detection of magnetic field –Characterisation of their magnetic fields –Compare to the magnetic fields of Ap/Bp stars  Fossil field hypothesis test –vsini determination –Compare to vsini of Ap/Bp star –vsini as a function of age  Origin of slow rotation hypothesis tests

5. E. Alecian Armagh Workshop 21/02/2008 Strategy (2) Observations of the Herbig stars in young clusters and associations –stars of a single cluster: = age and = initial conditions –≠ clusters  ≠ ages and ≠ initial conditions  Disentangle evolutionary effects from initial condition effects  Understand the evolution of the magnetic field during the PMS phase, and its impact on the evolution of the stars

6. E. Alecian Armagh Workshop 21/02/2008 The Herbig Ae/Be stars A and B stars with emission lines IR emission Association with nebulae Intermediate-mass PMS stars  Progenitors of the main sequence A/B stars Characteristics associated with magnetic activity : –resonance lines as N V and O VI, X-ray emission :  hot chromospheres or coronae (e.g. Bouret et al. 1997) –magnetospheric accretion (e.g. Mannings & Sargent 1997) –rotational modulation of resonance lines :  wind structured by magnetic field (e.g. Catala et al. 1989, 1999) } definition (Herbig 1960)

7. E. Alecian Armagh Workshop 21/02/2008 Magnetic fields in Herbig Ae/Be stars ? AB Aur : Catala et al. (1993), Catala et al. (1999)  no detection HD 100546 : Donati et al. (1997)  no detection HD 104237 : Donati et al. (1997)  1st detection (recently confirmed) HD 139614 : Hubrig et al. (2004)  detection not confirmed with more accurate observations HD 101412 : Wade et al. (2007)  detection (recently confirmed) But now we have ESPaDOnS !

8. E. Alecian Armagh Workshop 21/02/2008 ESPaDOnS (CFHT, Hawaii) High-resolution spectropolarimeter : R = 65000, broad spectral range (370 - 1080 nm) Reduction : Libre-Esprit package (Donati et al. 1997, 2007) Least Squares Deconvolution method (Donati et al., 1997)  More lines, better S/N ratio, larger magnitude V range of the star  Increase our chances to detect magnetic fields

9. E. Alecian Armagh Workshop 21/02/2008 Field Herbig Ae/Be stars (HAeBe) study

10. E. Alecian Armagh Workshop 21/02/2008 Our sample Catalogues : Vieira et al. (2003) and Thé et al. (1994) 55 Herbig Ae/Be stars 1.5 – 15 Msun PMS life = from birthline to ZAMS birthlines Palla & Stahler (1993) ZAMS 

11. E. Alecian Armagh Workshop 21/02/2008 Our sample Catalogues : Vieira et al. (2003) and Thé et al. (1994) 55 Herbig Ae/Be stars 1.5 – 15 Msun PMS life = from birthline to ZAMS Stars: –with convective envelope, or –with convective core, or –totally radiative  Convective envelope disappearing Convective core apparition

12. E. Alecian Armagh Workshop 21/02/2008 Observations and reduction For each star: –(one or many) Stokes I and V spectra –Determination of T eff and log(g) –LSD method: mask of T eff and log(g) of the star, not including Balmer lines and lines contaminated by emission –Searching for a Zeeman signature in the LSD V profile

13. E. Alecian Armagh Workshop 21/02/2008 Results A0, vsini~8.6 km/s Wonderful Zeeman signatures !!! B3, vsini~26 km/sB9, vsini~41 km/s A2, vsini~9.8 km/s 55 observed, 4 magnetic  ~7% magnetic Herbig Ae/Be stars

14. E. Alecian Armagh Workshop 21/02/2008 HD 200775 Binary SB2 (P~3.9 y) Alecian et al. (2008)

15. E. Alecian Armagh Workshop 21/02/2008 HD 200775 Binary SB2 (P~3.9 y) Alecian et al. (2008)

16. E. Alecian Armagh Workshop 21/02/2008 HD 200775 Binary SB2 (P~3.9 y) TB~TA=19000 K Primary magnetic, vsini~26 km/s Secondary non-magnetic, vsini~56 km/s Emission from the secondary Secondary largely redder than the primary  Ls>Lp and Ms>Mp Alecian et al. (2008)

17. E. Alecian Armagh Workshop 21/02/2008 HD 72106 Binary SB2 –asini = 0.8 " –Porb>1600 d Primary: B9 Ap ZAMS, magnetic, vsini~41 km/s Secondary: A3 PMS, non-magnetic, vsini~54 km/s Folsom et al., in prep.

18. E. Alecian Armagh Workshop 21/02/2008 HD 72106 P S Folsom et al., in prep.

19. E. Alecian Armagh Workshop 21/02/2008 HD 72106 Binary SB2 –asini = 0.8 " –Porb>1600 d Primary: B9 Ap ZAMS, magnetic, vsini~41 km/s Secondary: A3 PMS, non-magnetic, vsini~54 km/s Folsom et al., in prep.

20. E. Alecian Armagh Workshop 21/02/2008 HD 190073 Single, PMS Te = 9250K, vsini=0-8.3 km/s Numerous emission in the spectrum: fwhm = 65 km/s Catala et al. (2007)

21. E. Alecian Armagh Workshop 21/02/2008 HD 190073 Catala et al. (2007)

22. E. Alecian Armagh Workshop 21/02/2008 HD 190073 Single, PMS Te = 9250, vsini=0- 8.3 km/s Numerous emission in the spectrum: fwhm = 65 km/s Halpha: Pcygni  dM/dt = 1.4 10 -8 M  /y  v  = 290 km/s  Tbase = 18000 K Catala et al. (2007)

23. E. Alecian Armagh Workshop 21/02/2008 V380 Ori

24. E. Alecian Armagh Workshop 21/02/2008 V380 Ori

25. E. Alecian Armagh Workshop 21/02/2008 V380 Ori Tp = 10500 KTs = 6000 K

26. E. Alecian Armagh Workshop 21/02/2008 V380 Ori

27. E. Alecian Armagh Workshop 21/02/2008 V380 Ori Binary SB2 Primary: B9 magnetic Secondary: G0.5 non- magnetic LSD profiles

28. E. Alecian Armagh Workshop 21/02/2008 V380 Ori PrimarySecondary LSD Profiles vsiniP~10 km/svsiniS~20 km/s

29. E. Alecian Armagh Workshop 21/02/2008 Magnetic field characterisation : Method Observations of the stars at different rotation phase Compute I and V: –I( ,  ) : G(  instr,v( ,  ) ) –V( ,  )  dI/d B l ( ,  ) (weak field approximation) –B l ( ,  ) : oblique rotator model (Stift 1975) –Integration over the surface : limb-darkening law Comparison of the synthetic to observed I, V and B l Compute  2 for (P,  0, ,B d,d dip )  2 minimisation B  Obs D d dip  i

30. E. Alecian Armagh Workshop 21/02/2008 Magnetic field characterisation : HD 200775 P = 4.328 d. i = 13 °  = -102° B d = 1000 G d dip = 0.10 R * On the ZAMS: P = 1.2 d B d = 3.6 kG Alecian et al. (2008)

31. E. Alecian Armagh Workshop 21/02/2008 Magnetic field characterisation : HD72106 P = 0.63995 d. i = 23°  = 60° B d = 1300 G d dip = 0 R * Folsom et al., in prep. On the ZAMS: P = 0.63995 d B d = 1.3 kG

32. E. Alecian Armagh Workshop 21/02/2008 Catala et al. (2007) Magnetic field characterisation : HD 190073 3 different hypothesis : –Pole-on star –  = 0 –Long Period In all cases: –Simple dipolar Zeeman signature –Signature stable over more than 2 years  strong probability for an organised magnetic field B d = 100 - 1000 G ZAMS: B d = 400 - 4000 G

33. E. Alecian Armagh Workshop 21/02/2008 Magnetic field characterisation : V380 Ori P = 7.6 d. i = 34°  = -95° B d = 1.4 kG d dip = 0 R * P = 9.8 d. i = 47°  = -95° B d = 1.4 kG d dip = 0 R * 2 dipole solutions ZAMS P=4.5 d B d =2.4kG ZAMS P=5.8 d B d =2.4kG

34. E. Alecian Armagh Workshop 21/02/2008 Other detections SemelPol +UCLES (AAT) = antecedent of ESPaDOnS Simple Zeeman signature consistent with an organised field HD 104237HD 101412 A4, vsini = 11.6 km/s B l = -50 G A0, vsini = 4.8 km/s B l = -120 G Thanks to S.C. Marsden

35. E. Alecian Armagh Workshop 21/02/2008 First conclusions 7% magnetic HAeBe stars Projection of magnetic Ap/Bp stars on the PMS phase  prediction of 5-10% magnetic HAeBe stars Large scale organised magnetic field Magnetic intensity of the HAeBe projected on the ZAMS : same order of the intensity of B(Ap/Bp): (assuming the magnetic flux conservation)  HD 200775: on the ZAMS B d = 3.6 kG  V380 Ori: on the ZAMS B d = 2.4 kG  HD 72106: already on the ZAMS B d = 1.3 kG  HD 190073: on the ZAMS B d = 400 - 4000 G  Strong arguments in favour of the fossil field theory

36. Statistical Study

37. E. Alecian Armagh Workshop 21/02/2008 The undetected sample 41 stars Detection significance distribution Monte-Carlo simulation: –i: random distribution –  : bimodal distribution (0° or 90°) –random phase for each data –dipole of fixed B Wade et al., in prep.

38. E. Alecian Armagh Workshop 21/02/2008 The undetected sample 41 stars Detection significance distribution Monte-Carlo simulation: –i: random distribution –  : bimodal distribution (0° or 90°) –random phase for each data –dipole of fixed B Wade et al., in prep.

39. E. Alecian Armagh Workshop 21/02/2008 The undetected sample 41 stars Detection significance distribution Monte-Carlo simulation: –i: random distribution –  : bimodal distribution (0° or 90°) –random phase for each data –dipole of fixed B Wade et al., in prep.

40. E. Alecian Armagh Workshop 21/02/2008 The undetected sample 41 stars Detection significance distribution Monte-Carlo simulation: –i: random distribution –  : bimodal distribution (0° or 90°) –random phase for each data –dipole of fixed B Kolmogorov-Smirnov test  Homogeneous population of dipole with B<450 G Wade et al., in prep.

41. E. Alecian Armagh Workshop 21/02/2008 Distribution of vsini All field magnetic HAeBe are slow rotators No magnetic HAeBe are fast rotators Magnetic HAeBe stars seem to have been braked more than the non-magnetic HAeBe stars Magnetic HAeBe stars Non magnetic HAeBe stars

42. E. Alecian Armagh Workshop 21/02/2008 Period in function of time No clear evolution of the period Majority of HAeBe: between 40 and 80% of their PMS track To study period evolution we need younger stars than our sample

43. E. Alecian Armagh Workshop 21/02/2008 Evolution of vsini to the ZAMS vsini HAeBe on the ZAMS close to normal A/B stars Evolution from HAeBe age to MS consistent with angular momentum conservation Normal A/B stars Normal HAeBe Normal HAeBe on the ZAMS Royer et al. (2007)

44. E. Alecian Armagh Workshop 21/02/2008 Cluster study

45. E. Alecian Armagh Workshop 21/02/2008 NGC 6611 sample Age = ~1 Myr  Younger than HAeBe 3 - 20 Msun  Fill the hole in the HRD 

46. E. Alecian Armagh Workshop 21/02/2008 NGC 2244 Sample Age ~ 8 Myr 2 - 20 Msun

47. E. Alecian Armagh Workshop 21/02/2008 NGC 2264 sample Age = 9Myr 1.5 - 9 Msun

48. E. Alecian Armagh Workshop 21/02/2008 Cluster results NGC6611 W601NGC 2264 83NGC2244 201 17 observed stars 1 magnetic 17 observed stars 1 magnetic 29 observed stars 1 magnetic B1.5, vsini~180 km/sB1, vsini~25 km/sB3, vsini~65 km/s Alecian et al. (2008), accepted

49. E. Alecian Armagh Workshop 21/02/2008 vsini of the cluster magnetic stars NGC6611 W601180 km/s ~ 1 Myr B1.5 NGC2244 201 25 km/s ~ 8 Myr B1 Can we see a sign of the evolution of the rotation in the magnetic HAeBe stars? vsiniageSp.T. Alecian et al. (2008), accepted

50. E. Alecian Armagh Workshop 21/02/2008 Conclusions (1) : Field HAeBe study Magnetism: –7% magnetic HAeBe –HAeBe magnetism in favour of the fossil field hypothesis Rotation: –vsini(magnetic HAeBe) < vsini(non magnetic HAeBe) –Magnetic HAeBe: slow rotators and very young  A braking mechanism acts very early during the PMS phase –Dvsini(HAeBe on ZAMS) = Dvsini(A/B Norm)  Constant angular momentum evolution from the age of HAeBe to the MS

51. E. Alecian Armagh Workshop 21/02/2008 Conclusions (1): preliminary cluster study Magnetism –Detections in 2 cluster, none in one cluster  The initial conditions may play a role on the presence (or on the intensity) of magnetic fields Rotation –At 1Myr, one magnetic star with vsini~200 km/s  Promising for the study of the angular momentum evolution, as well as the impact of magnetic field on the rotation evolution of HAeBe stars

52. E. Alecian Armagh Workshop 21/02/2008 Conclusion (2): Fossil Field against Convective Core hypothesis 5 magnetic stars are in the totally radiative phase These stars have the same type of magnetic field of the stars with a convective core  Core convection does not appear to be responsible for the presence of magnetic fields in HAeBe stars  The magnetic fields of the intermediate mass stars are very likely FOSSIL

53. E. Alecian Armagh Workshop 21/02/2008 Open Issues Unanswered questions : –Only a fraction of stars is magnetic : why all the stars are not magnetic ? –Clusters: idem –Binaries : one magnetic + one non-magnetic –Decentered dipole (or dipole + quadrupole) : how the molecular cloud contraction can form that field topology ? –The active stars are not magnetic After de main sequence phase: giant phase, white dwarfs, neutron stars ? Before the PMS phase: molecular cloud contraction, proto- stellar phase ? What constraints on the magnetic winds and magnetospheric accretion models can we put using our results ? Can we lower the detection limit of the undetected sample ?

54. E. Alecian Armagh Workshop 21/02/2008 HD 35929 Observed with Narval A5 vsini~60 km/s Inside the instability strip of delta-Scuti pulsators Need more observations