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Stellar evolution in the post-AGB stage

Or... “An optical catalogue of post-AGB candidates”. Stellar evolution in the post-AGB stage. Olga Suárez Laboratorio de Astrofísica Espacial y Física Fundamental – Madrid (Spain). Supervisors: Minia Manteiga Outeiro Pedro García Lario.

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Stellar evolution in the post-AGB stage

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  1. Or... “An optical catalogue of post-AGB candidates” Stellar evolution in the post-AGB stage Olga Suárez Laboratorio de Astrofísica Espacial y Física Fundamental – Madrid (Spain) Supervisors: Minia Manteiga Outeiro Pedro García Lario In colaboration with: Arturo Manchado, Ana Ulla, S.R. Pottasch

  2. Objectives • Study of stars in the transition phase from AGB to PN. • Catalogue - large number of objects • Multiwavelength study - SEDs • Use of statistical tools

  3. Objectives • Study of stars in the transition phase from AGB to PN. • Catalogue - large number of objects • Multiwavelength study - SEDs • Use of statistical tools

  4. Stellar evolution

  5. Post-AGB evolution (Blöcker, 1995)

  6. Nomenclature used in this work • Post-AGB: AGB mass loss has ceased. not ionized envelope • Transition objects: stellar continuum forbidden lines (no [OIII]) • Planetary Nebula (PN): no stellar continuum forbidden lines

  7. The catalogue - Selection criteria • IRAS colours: • [12] – [25] = 2.5  log (F12m/F25m) • [25] – [60] = 2.5  log (F25m/F60m) • Flux ratios: • F12m /F25m 0.50 • F25m/F60m 0.35 • F60m/F100m 0.60 • Low IRAS variability  to avoid AGBs

  8. The catalogue in the IRAS c-c diagram

  9. The catalogue - spectroscopic observations

  10. The catalogue - imaging observations

  11. The catalogue - the search Hα - cont Hα

  12. The catalogue - the search

  13. The catalogue - the search IRAS 17395-0841 Hα [NII] Riera et al., RevMexAA, 2003 Suárez et al., in preparation Hα

  14. The catalogue - number of objects • 255 observed objects • 104post-AGB stars (with optical spectra) • 21 transition objects • 36Planetary Nebulae • 3 AGB stars • 38 young stellar objects or HII regions • 2 Seyfert galaxies • 5 peculiar stars • 47 objects without optical counterpart (42 believed to be obscured post-AGB stars)

  15. The catalogue - a sample

  16. The catalogue - a sample

  17. Analysis of the spectra • Spectral classification of post-AGB stars and young stellar objects. • Comparison with catalogues (Silva, 1992; Pickles, 1998; Jacoby, 1984) Relative flux Wavelength

  18. Analysis of the spectra • Excitation classes for PNe (Morgan, 1984; Dopita, 1990; and Crowther, 1998) • Based on strength line ratios.

  19. Analysis of the spectra

  20. Spectral Energy Distributions • Data from optical spectra, 2MASS, MSX, IRAS. • Classification according to van der Veen et al. (1989) Class I Class II Class III Class IVa Class IVb

  21. IRAS colour-colour diagram • Models by van Hoof et al. (1997), based on Blöcker (1995), show the evolution in this diagram.

  22. IRAS colour-colour diagram

  23. Conclusions • Observations - selection criteria based on IRAS colours • Catalogue - 255 sources: 104 post-AGB stars, 21 transition objects, 36 PNe. • Spectra and SEDs classified - multiwavelength analysis using statistical tools

  24. Galactic latitude distribution • Statistical indicator of the mass of a population of stars. • High latitude (wide galactic latitude distribution)  lower mean mass • Low latitude (narrow galactic latitude distribution)  higher mean mass

  25. Results • Evolutionary status + Galactic latitude + statistics Post-AGB stars and PNe have different galactic latitude distributionfrom obscured post-AGB stars Objects without optical counterpart are obscured post-AGB stars similar to those not observed

  26. Conclusions • Observations - selection criteria based on IRAS colours • Catalogue - 255 sources: 104 post-AGB stars, 21 transition objects, 36 PNe. • Spectra and SEDs classified - multiwavelength analysis using statistical tools

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