1. Stellar evolution and the ‘O-rich AGB sequence’ F. Jiménez-Esteban 1,2, P. García-Lario 2 & D. Engels 1 1- Hamburger Sterwarte / Universität Hamburg 2- ISO Data Center / European Space Astronomy Center

2. Well defined location of O-rich AGB stars in the IRAS c-c diagram Sequence of increasing optical thickness of the CSE: 3 possible interpretations: - Evolutionary - Progenitor mass - Combination of both AGB PN Stellar evolution and the ‘O-rich AGB sequence’ The ‘O-rich AGB sequence’ van der Veen & Habing, 1988, A&A, 194, 125 Thinner Bluer Thicker Redder

3. Stellar evolution and the ‘O-rich AGB sequence’ The sample Two previous photometric analysis of OH/IR stars: I - Arecibo sample - 363 (Jiménez-Esteban et al., 2005, A&A, 431, 779) II - GLMP sample - 94 (Jiménez-Esteban et al., 2005, A&A, submitted) Samples are not directly comparable, but complementary: i) Arecibo: blue colours GLMP: red colours ii) Arecibo: Arecibo sky GLMP: the entire sky (32% of GLMP in the GB) 457 OH/IR stars providing very good coverage

4. Stellar evolution and the ‘O-rich AGB sequence’ Bolometric Flux Well covered Spectral Energy Distribution J-H-K ( own obs. or 2MASS ); A-C-D-E ( MSX ); 12-25-60-100 ( IRAS ) (1.25 - 1.65 - 2.2  m ) (8.28 - 12.13 - 14.65 - 21.3  m ) Integration: trapezium rule + Extrapolation F bol

5. Stellar evolution and the ‘O-rich AGB sequence’ Absolute bolometric luminosity 41 GLMP OH/IR in the direction of the Galactic Bulge D  8kpc Wide range  2500 – 26000 L  Maximum in  3500 L  Coincidence with other authors who studied mainly bluer samples of OH/IR stars in the GB and in the solar neighborhood We assume L OH/IR  3500 L  Distance & Galactic Height ( Habing et al. 1985; Rowan-Robinson & Chester 1987; Jones et al. 1994; Blommaert et al. 1998; Wood et al. 1998; Jackson et al. 2002; Knauer et al. 2001 ) The luminosity function may be similar throughout the Galaxy and not very dependent on the colours

6. Stellar evolution and the ‘O-rich AGB sequence’ Parametrization [12] –[25] adequate descriptor for the blue part of the sequence [25] –[60] adequate descriptor for the red part of the sequence We parameterize the curve: Lower λ Bluer Higher λ Redder

7. Stellar evolution and the ‘O-rich AGB sequence’ Galactic Height Relation between and the galactic height red OH/IR stars are concentrated towards the Galactic Plane The red part of the O-rich AGB sequence must be populated mainly with objects of higher mass

8. Stellar evolution and the ‘O-rich AGB sequence’ Expansion velocity Deficit of OH/IR stars with high v exp at large GH Systematic trend: high v exp in OH/IR stars with small GH Low v exp associated to low High associated to high v exp Low OH/IR stars covers the whole range of v exp The red part of the O-rich AGB sequence is mainly populated by high progenitor mass and high V exp stars The blue part of the O-rich AGB sequence is populated by OH/IR stars with a wide range of V exp and progenitor masses

9. Stellar evolution and the ‘O-rich AGB sequence’ Evolutionary Scenario All OH/IR stars would start the AGB phase, independent of their progenitor mass, in the blue part of the O-rich AGB sequence, and then they would evolve toward redder colors, although only the more massive stars would reach the red end of the O-rich AGB sequence.

10. Stellar evolution and the ‘O-rich AGB sequence’ Galactic Scale Height ∆ = 0.3 Galactic scale height ( H ): Range N of stars H ( pc ) Ext. blue  0.6 43536 Blue 0.6 <  1.2 193344 Transition 1.2 <  1.8 58287 Red 1.8 <  3.0 66193 Ext. red 3.0 < 2248 Thin CSE Thin & Thick CSE Thick CSE

11. Stellar evolution and the ‘O-rich AGB sequence’ Evolutionary connection Extremely blue ( H = 536 pc ) Optical Miras with short-P ( H = 600 pc ) (Jura 1994) Type III PN ( = 660 pc ) (Maciel & Dutra 1992) Blue ( H = 344 pc ) Solar neighbourhood OH/IR ( H = 330 pc ) (Ortiz & Maciel 1996) Miras close to the Galactic Plane ( H = 315 pc ) (Wood & Cahn 1977) Type II PN ( = 350 pc ) (Maciel & Dutra 1992)

12. Stellar evolution and the ‘O-rich AGB sequence’ Transition ( H = 287 pc ) Intermediate- and long-P Miras ( H = 240 pc ) (Jura & Kleinmann 1992) Optical C-rich stars ( H = 290 - 260 pc ) (Groenewegen et al. 1992) ( Massive ) Type II PN ( 250 < 350 pc ) Red ( H = 193 pc ) IR C-stars ( H = 155-200 pc ) (Groenewegen et al. 1992; Claussen et al. 1996) O-rich HBB AGB stars (N-rich) Type I PN ( = 150 pc ) (Maciel & Dutra 1992) Extremely red ( H = 48 pc ) Infrared PN? ( OHPNe ) Evolutionary connection

13. Stellar evolution and the ‘O-rich AGB sequence’ Conclusions Unique sample of ~450 OH/IR to study the O-rich AGB sequence Found a triple relation among Progenitor mass - - v exp Postulated an evolutionary scenario which need to be further investigated Defined 5 main groups and established evolutionary connections between all kind of AGB stars and PNe

14. Stellar evolution and the ‘O-rich AGB sequence’