New insights into the close circumstellar environment of the Herbig Ae/Be stars

1. New insights into the close circumstellar environment of the Herbig Ae/Be stars M. Deleuil, J.C. Bouret Laboratoire d'Astrophysique de Marseille • C. Catala, Observatoire de Paris, • P. Feldman, JHU • A. Lecavelier des Etangs, IAP • C. Martin, LAM • A. Roberge, Carnegie Institution of Washington • T. Simon U. Hawaï • A. Vidal-Madjar, IAP

2. FUSE: a spectrograph in the FUVspectral range : 910 - 1180Å – R ~ 15 000

3. 4 3 Log L / L 2 1 4.6 4.4 4.2 4 3.8 3.6 Log Teff The circumstellar disk program 20 Herbig Ae/Be stars and a few main sequence stars. HD 76534 B2,  0.5 Myr HD 259431 B5,  1 Myr HD 38087 B5,  0.5 Myr HD 85567 B5V, 1 Myr AB Aur A0V, 2.6 Myr HD 250550 B7, 1 Myr HD 163296 A1V,4.7 Myr HD 100546 B9V,  9 Myr ß Pictoris A5V, 20 Myr HD 176386 B9V, 2.8 Myr HD 141569A B9.5V, 4.7 Myr HR 5999 A5Ve, 0.7 Myr Van den Ancker et al. (1997 & 1998)

4. Evolved objects Main sequence stars : emission lines in the FUV in stars with Teff ≤ 8200 K (Simon et al., 2002) 12800K Pre-main sequence stars : emission lines in stars with Teff ≤ 11 500 K 10700K 10500K 10500K 10040K 9800K 8700K 7300K Bouret, Deleuil, Simon & Catala in preparation

5. C III Hot emission lines

6. Hot emission lines • formation temperatures: up to 300 000K • broad : up to +/- 500 km/s

7. HD 100546 : OVI λ1032 HD100546 Hot emission lines • formation temperatures: up to 300 000K • broad : up to +/- 500 km/s • complex profiles: bulk of the emission redshifted • variations in intensity: time scale > a few days Deleuil, Lecavelier, Bouret et al., 2004

8. Chromosphere Fluorescent decays in Fe II Harper et al., 2001 ; Deleuil et al., 2004b

9. Same origin for hot species log10(F(O VI)) log10(F(C III)) But which process ?

10. the width of the observed lines is too large! at most equal to the free-fall velocity (Lamzin 1998) mass loss • additionalveiling is expected needs to be investigated Key points: disk Magnetospheric accretion: • Magnetic field detected in HD 104237 (Donati 1997) • some stars have a CS disk imaged; • temperature of a few 106 K in the shock region; • variations in the line profiles.

11. similarities of line widths in stars with different vsini ! • additionalveiling is expected needs to be investigated Key points: Magnetically confined wind: Babel & Montmerle, 1997  X-rays emission in Ap and Bp stars • mass loss required; • shock region extended with temperature of a few 106 K • variations in the line profiles.

12. Log10( F(O VI)) Log10(F(X-rays)) Log10(F(O VI)) Log10( F(O VI)) V sini (km/s) Log10(F(O VI)) Log10( Age Myr) ● 2 Log10(1/2 M Vinf) No correlation between FUV flux and : the age of the system the star's rotation the mass loss the X-ray emission the environment: CS disk or not, inclination ..

13. Activity in the FUV characteristics of the Herbig Ae & B9 Common processes in stars with a wide range of stellar parameters No trend in any stellar parameter hot layers above the photosphere : structure: still to be better determined heating mechanism: still to be explicitely identified theoritical models are required .. Periodicity in flux variation should be explored Conclusion

14. H2in the FUSE spectral domain: Lyman transitions B-X ( ) Werner transitions C-X ( ) J v=0 Franck Le Petit, PhD Thesis (2002) Molecular gas: • The most abundant molecule in the CS environment of young stars • Constrains the reservoir of gas for planets building • Protected by " Self-Shielding " Numerous lines in the FUV

15. H2 detected in absorption: Airglow lines

16. OVI doublet 1032-1038 Å H2 detected in absorption: Airglow lines

17. Green: Stellar Continuum Blue : Intrinsic Profile Red : Resulting Profile Column densities Radial velocities Line widths (b) Analysis of the H2 lines: The Owens Profile Fitting Procedure (M. Lemoine et al. 2002) Gas bound to the star Martin et al. (2004)

18. H2 thermalized up to J=3 H2 thermalized up to J=4 Excitation diagrams :

19. Excitation Conditions = Interstellar Medium Gry et al. (2002) AB Aurigae : • H2 thermalized up to J=2 • Excitation temperature ~ 50K H2 detected by FUSE: Remnant of the original molecular cloud Very extended disk with an inclination angle: 27°    35°from the plane of the sky (Eisner et al. 2003, Mannings & Sargent 1997)

20. HD 100546 & HD 163296 • Stars surrounded by disks • H2 Thermalized up to J=4 Collisionally excited medium close to the star < 5 AU (Lecavelier des Etangs, Deleuil et al. 2003) • Disks inclination angles to the lines of sight: (Grady et al. 2000; Augereau et al. 2001) • HD 163296:  = 60° 5° • HD 100546:  = 51°  3° Extended chromosphere located above the disk ?

21. B8 – B2 stars • H2 Thermalized up to J=3 • J=0-3 Temperature: ~100 K • Higher J-levels ~1300 K Very similar to the H2 excitation in PDRs HERBIG Be STARS Bouret, Martin et al. (2003)

22. To reproduce the excitation diagram: 2 PDRs are needed: • a large PDR with low density for the lower J-levels • a dense PDR close to the star for the higher J-levels Compatible with images: • MSX (A band 8.8 µm): Hot dust close to the star • DSS2 (R and I bands): Very large dark cloud Martin et al. (in prep) RESULTS FOR HD 259431 PHOTODISSOCIATION REGIONS MODEL J. Le Bourlot,"Molecules in the Universe" Team, Observatoire de Paris

23. HAeBes : 2 different mechanisms of excitation of H2 Conclusion • Youngest stars of the sample - HBe Envelopes: remnant of their original cloud HD 259431: PDRs models with 2 components TBD : complete the analysis for the whole sample (under progress) • Stars with circumstellar disk Collisionally excited medium close to the star Goal: explain the excitation diagrams of stars with disk TBD: include radiative transfer of H2 in models of disk Differences : faster evolution and/or stronger radiation field.