AGB - Asymptotic Giant Branch wykład V circumstellar envelopes of AGB stars

1. AGB - Asymptotic Giant Branchwykład Vcircumstellar envelopes of AGB stars RyszardSzczerba Centrum Astronomiczne im. M. Kopernika, Toruń szczerba@ncac.torun.pl (56) 62 19 249 ext. 27 http://www.ncac.torun.pl/~szczerba/

2. „Asymptotic Giant Branch” Harm Habing, Hans Olofsson (Eds.) A&A Library, 2004 Springer-Verlag

3. AGB Stars: summary of mass loss modelling

4. AGB Stars: steady state mass loss Woitke

5. AGB Stars: time-dependent mass loss Woitke

6. AGB Stars: AGB chaos (Woitke)

7. AGB Stars: AGB chaos (Woitke)

8. AGB Stars: mass loss history Sahai (1998)

9. AGB Stars: circumstellar arcs Mauron & Huggins (1999)

10. AGB Stars: circumstellar arcs

11. AGB Stars: circumstellar arcs Kwok et al. (2001)

12. AGB Stars: models of pulsating stars Hoefner et al. (1997)

13. AGB Stars: dust induced instability Fleischer et al. (1991); Hoeffner et al. (1995)

14. AGB Stars: dust induced instability Simis et al. (2001)

15. AGB Stars: dust induced instability Simis et al. (2001) Subsonic part of CSE

16. Known Inter- or Circum-stellar Molecules

17. Aldehydes Ketones Alcohols methanol ethanol acetone formaldehyde acetaldehyde Ethers Carboxylic Acids Esters Dimethyl ether formic acid acetic acid methyl formate Amides Glycoladehydes Amino Acids Rings formamide glycolaldehyde glycine cyclopropenylidene ethylene oxide Interstellar Organic Molecules

18. Interstellar and circumstellar molecules: • 132 molecular species have been detected • inspace (203 including isotopomers, 50 in comets), see, e.g., http://www.nrao.edu/~awootten; • - first detection of NH2CH2COOH - glycine, is the simplest amino acid (ApJ 593, 848, 2003; towards SgrB2(N), W51 and Orion KL).

19. Cosmic rays produce ions

20. ASTROCHEMICAL NETWORKS

22. rate equations

23. Dust particles contain ~1% of circumstellar matter.

28. TYPES OF SURFACE REACTIONS REACTANTS: MAINLY MOBILE ATOMS AND RADICALS A + B AB association H + H H2 H + X XH (X = O, C, N, CO, etc.) WHICH CONVERTS O  OH  H2O C CH  CH2  CH3  CH4 N  NH  NH2  NH3 CO  HCO  H2CO  H3CO  CH3OH X + Y XY (CO + O  CO2) ?????????? D atoms react in same manner as H atoms

29. MODELLING DIFFUSIVE SURFACE CHEMISTRY Rate Equations The rate coefficient is obtained by Method accurate if N>1 Biham et al. 2001

30. AGB Stars: circumstellar chemistry Markwick (2000)

31. AGB Stars: The chemical equilibrium K: dissociation equilibrium constant U: partition function

32. Markwick (2000) O-rich: C/O=0.75; T=2215 K C-rich: C/O=1.5 T=2300 K (IRC +10216) Fractional abundance: n(A)/n(H2)

34. AGB Stars: circumstellar chemistry Markwick (2000) ; fract. abund.-> partial pressure

35. AGB Stars: circumstellar chemistry Markwick (2000) ; fract. abund.-> partial pressure

36. AGB Stars: circumstellar chemistry Markwick (2000)

37. Shock waves transfer their energy to the gas by increase of: • Kinetic energy; • Internal energy. • Shocked gas cools: Internal energy kifferent regions are given a consistent treatment. • Radiative cooling (more efficient in higher densities); • Adiabatic expansion. • If the gas parcel experiences a second shock before it returns to its initial position, it my attain a net outward momentum (mass loss). AGB Stars: efect of (periodic) shocks

38. AGB Stars: efect of (periodic) shocks

39. AGB Stars: efect of (periodic) shocks

40. AGB Stars: efect of (periodic) shocks

41. Willacy & Cherchneff (1988)

42. AGB Stars: efect of (periodic) shocks Willacy & Cherchneff (1988)

43. Willacy & Cherchneff (1988)

44. AGB Stars: circumstellar chemistry Markwick (2000)

45. AGB Stars: outer shell chemistry (IRC+10216)

46. AGB Stars: outer shell chemistry (IRC+10216)

47. AGB Stars: outer shell chemistry (IRC+10216)

48. „Typical”Circumstellar Spectra Cernicharo et al. 2000

49. General considerations • Radiative transfer (along a ray) Scattering: Complete Frequency Redistribution Complete Frequency Redistribution

50. General considerations Formal solution: