1 / 163

Driving mechanism and energetic aspects of pulsations in g Doradus stars

Driving mechanism and energetic aspects of pulsations in g Doradus stars. M.-A. Dupret. LESIA, Paris Observatory, France. Grigahcène. Miglio J. Montalban. Algiers, Algeria. Liège, Belgium. Driving mechanism and energetic aspects in g Doradus stars. Amplitude and phases.

nerys
Download Presentation

Driving mechanism and energetic aspects of pulsations in g Doradus stars

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Driving mechanism and energetic aspects of pulsations in g Doradus stars M.-A. Dupret LESIA, Paris Observatory, France • Grigahcène • Miglio J. Montalban Algiers, Algeria Liège, Belgium

  2. Driving mechanism and energetic aspects in g Doradus stars Amplitude and phases Excitation Mode identification

  3. g Doradus stars Internal physics: Convection and partial ionization zones • 1 convective core • 1 convective envelope Fc/F k He an H partial ionization zones are inside the convective envelope rad = (Γ3-1) / 1

  4. dS0 Coupling between • the dynamical equations and • the thermal equations g Doradus stars Driving mechanism Main driving occurs in the transition region where the thermal relaxation time is of the same order as the pulsation periods For a solar calibrated mixing-length, the transition region for the g-modes is near the convective envelope bottom. Non-adiabatic region Quasi-adiabatic region Log(tth) g50

  5. g Doradus Driving mechanism Flux blocking at the base of the convective envelope Motor thermodynamical cycle

  6. g Doradus Driving mechanism Flux blocking at the base of the convective envelope Motor thermodynamical cycle Luminosity variation Work integral M = 1.6 M0 , Teff = 7000 K , a = 2 , Mode l=1, g50

  7. M = 1.6 M0 Teff = 7000 K a = 2 Mode l=1, g50 g Doradus Driving mechanism Role of time-dependent convection Fc / F tc : Life-time of convective elements s : Angular frequency Log (stc )

  8. 3-D hydrodynamic simulations Analytical approach All motions are convective ones Separation between convection and pulsation in the Fourier space of turbulence In particular the p-modes (present in the solution) Convective motions: short wave-lengths Oscillations: long wave-lengths Nordlund & Stein Samadi, Belkacem (Meudon) 1. Static solution without oscillations 2. Stability study of this solution Oscillations Perturbation MLT Gough´s theory Gabriel´s theory Convection – pulsation interaction Gabriel´s theory

  9. Convection – pulsation interaction: Gabriel´s theory Hydrodynamic equations Convective fluctuations equations Mean equations Perturbation Perturbation Equations of linear non-radial non-adiabatic oscillations Correlation terms • Convective flux • Reynolds stress Perturbation of • Turbulent kinetic • energy dissipation

  10. Radiative luminosity Convective luminosity Turbulent pressure Turbulent kinetic energy dissipation Convection – pulsation interaction: Work integral

  11. M = 1.6 M0 Teff = 7000 K a = 2 Mode l=1, g50 g Doradus Driving mechanism WFRr: Radial radiative flux term

  12. M = 1.6 M0 Teff = 7000 K a = 2 Mode l=1, g50 g Doradus Driving mechanism WFRr: Radial radiative flux term WFcr: Radial convective flux term

  13. M = 1.6 M0 Teff = 7000 K a = 2 Mode l=1, g50 g Doradus Driving mechanism WFRr: Radial radiative flux term WFcr: Radial convective flux term Wpt: Turbulent pressure We2: Turbulent kinetic energy dissipation

  14. M = 1.6 M0 Teff = 7000 K a = 2 Mode l=1, g50 g Doradus Driving mechanism WFRr: Radial radiative flux term WFcr: Radial convective flux term WFh: Transversal convective and radiative flux

  15. M = 1.6 M0 Teff = 7000 K a = 2 Mode l=1, g50 g Doradus Driving mechanism WFRr: Radial radiative flux term WFcr: Radial convective flux term Wtot: Total work

  16. l = 1 Instability strips g Doradus

  17. Instability strips g Doradus l = 1

  18. g Dor g-modes • Sct p-g modes Unstable modes g Doradus

  19. Unstable modes g Doradus

  20. Unstable modes g Doradus Period range decreases with l

  21. Unstable modes g Doradus

  22. Key point: Location of the convective envelope bottom Instability region very sensitive to the effective temperature and the description of convection (a, …) Unstable modes g Doradus

  23. HD 209295 Handler et al. (2002) Tidally excited ? HD 8801 Henry et al. (2005) Am star HD 49434 Hybrid d Sct – g Dor Comparison : d Sct red edge (l=0, p1) g Dor instability strip (l=1)

  24. g Dor g-modes • Sct p-g modes Hybrid d Sct – g Dor Unstable modes

  25. Hybrid d Sct – g Dor Unstable modes Stable regions

  26. Hybrid d Sct – g Dor HD 49434 HD 49434

  27. Hybrid d Sct – g Dor Unstable modes (HD 49434) 2 4 0.5 20 40

  28. Hybrid d Sct – g Dor Work integral : l = 1 p2

  29. Hybrid d Sct – g Dor Work integral Work integral : l = 1 p2 p1

  30. Hybrid d Sct – g Dor Work integral Work integral : l = 1 p2 p1 g1

  31. Hybrid d Sct – g Dor Work integral Work integral : l = 1 p2 p1 g1 g2

  32. Hybrid d Sct – g Dor Work integral Work integral : l = 1 p2 p1 g1 g2 g3

  33. Hybrid d Sct – g Dor Work integral Work integral : l = 1 p2 p1 g1 g2 g3 g4

  34. Hybrid d Sct – g Dor Work integral Work integral : l = 1 p2 p1 g1 g2 g3 g4 g6

  35. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g6

  36. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g8 g6

  37. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g10 g8 g6

  38. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g12 g10 g8 g6

  39. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g15 g12 g10 g8 g6

  40. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g21 g15 g12 g10 g8 g6

  41. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g21

  42. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g21

  43. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g21 g30

  44. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g21 g30 g35

  45. Hybrid d Sct – g Dor Work integral Work integral : l = 1 g21 g30 g35 g40

  46. Hybrid d Sct – g Dor Work integral Work integral l = 1 , g25 l = 1 , g6

  47. Hybrid d Sct – g Dor Radiative damping mechanism Growth-rate

  48. Hybrid d Sct – g Dor Radiative damping mechanism Growth-rate < 0

  49. Hybrid d Sct – g Dor Work integral Propagation diagrams

  50. Hybrid d Sct – g Dor Work integral Propagation diagrams g-mode p-mode g-mode cavity Evanescent g-mode cavity

More Related