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The uniqueness of Antarctica for the study of AGB stars undergoing thermal pulses.

The uniqueness of Antarctica for the study of AGB stars undergoing thermal pulses. Optical and Infrared Wide-Field Astronomy in Antarctica Paris - 16/06/2006. Roald Guandalini – University of Perugia. ABSTRACT. Main Topics: Introduction on ground-based observations

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The uniqueness of Antarctica for the study of AGB stars undergoing thermal pulses.

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  1. The uniqueness of Antarctica for the study of AGB stars undergoing thermal pulses. Optical and Infrared Wide-Field Astronomy in Antarctica Paris - 16/06/2006 Roald Guandalini – University of Perugia Optical and Infrared Wide-Field Astronomy in Antarctica

  2. ABSTRACT Main Topics: • Introduction on ground-based observations from Antarctica of AGB stars p. 3-7 • Importance of mid-IR observations and variability for AGB stars p. 8-19 • Mid-IR observations from Antarctica: p. 20-21 • Some preliminary results and possible improvements through ground-based observations p. 22-31 Optical and Infrared Wide-Field Astronomy in Antarctica

  3. Introduction:Why AGB stars….. There are still many unclear points in the study of the AGB evolution… Uncertain Parameters… • Stellar LUMINOSITY (whose uncertainty influences estimates of other parameters…); • Stellar MASS; • MASS LOSS rates as a function of the evolutionary stage and of total mass; • Production of CHEMICAL ELEMENTS. Optical and Infrared Wide-Field Astronomy in Antarctica

  4. Introduction:Mid-Infrared Bands Mid-IR Bands…… Very important in the study of AGB stars (see later): • 3-5 um. • >10 um up to 30 um. Optical and Infrared Wide-Field Astronomy in Antarctica

  5. Introduction:Why Ground-Based Observations….. ISO MSX AGB stars have been observed by several space-borne telescopes in the mid-IR: IRAS, ISO, MSX, IRTS. BUT IR space-borne observations present some disadvantages: • The duration of the operational period is expected to be quite limited. • Observations with long time of integration are difficult. Single-epoch observations in most cases. Optical and Infrared Wide-Field Astronomy in Antarctica

  6. Introduction:Why Dome C….. Dome C: Best place on the Earth to perform astronomical observations in the mid-IR. See previous talks: 1) Site testing Dome C 2) Comparison of Dome C with other ground-based locations (i.e. Mauna Kea) Optical and Infrared Wide-Field Astronomy in Antarctica

  7. Introduction:Why Surveys from Dome C….. Important analysis needed for AGB stars: • Light curves and therefore variability. • Accurate study of the variations of luminosity (variability) over the wide region of the electromagnetic spectrum including optical and IR. Which kind of observations can be done from the ground ? • Surveys through wide field (future) or small area (IRAIT) imaging of interesting stellar systems. • Multiple observations of chosen AGB sources at different epochs & wavelengths. N.B. Extended wavelength coverage is fundamental. Indeed….. Optical and Infrared Wide-Field Astronomy in Antarctica

  8. Mid-IR and Variability:Mid-IR Observations with ISO(SWS) Mira Lb Sr PostAGB PostAGB Mira Optical and Infrared Wide-Field Astronomy in Antarctica

  9. Mid-IR and Variability:Period-Luminosity The contribute from mid-IR is fundamental to estimate luminosity of AGB stars. Period-luminosity relations are important to estimate important parameters of AGB stars. Wood et al. 1999 Kwok et al. 1999 Optical and Infrared Wide-Field Astronomy in Antarctica

  10. Mid-IR and Variability:Variability and Evolution Luminosity varies with time during the evolution of the star on the AGB phase. Commonly believed so far: Semiregulars in the the post-flash dips, Miras at the top of interpulse luminosity. Hence, one expects more Miras than SRs. Instead, the 2 populations are more or less equal (Guandalini et al 2006).  The variability is also dependent on the evolutionary status. Optical and Infrared Wide-Field Astronomy in Antarctica

  11. Mid-IR and Variability:Bolometric Variability (ISO) Optical and Infrared Wide-Field Astronomy in Antarctica

  12. Mid-IR and Variability:Bolometric Variability (ISO) Optical and Infrared Wide-Field Astronomy in Antarctica

  13. Mid-IR and Variability:Bolometric Variability (ISO) Optical and Infrared Wide-Field Astronomy in Antarctica

  14. Mid-IR and Variability:Bolometric Variability (ISO) Optical and Infrared Wide-Field Astronomy in Antarctica

  15. Mid-IR and Variability:Bolometric Variability (ISO) Optical and Infrared Wide-Field Astronomy in Antarctica

  16. Mid-IR and Variability:Bolometric Variability (ISO) Optical and Infrared Wide-Field Astronomy in Antarctica

  17. Mid-IR and Variability:Bolometric Variability (ISO) Optical and Infrared Wide-Field Astronomy in Antarctica

  18. Mid-IR and Variability:Bolometric Variability (ISO) Optical and Infrared Wide-Field Astronomy in Antarctica

  19. Mid-IR and Variability:Bolometric Variability (ISO) Bolometric variability……… How is this generated ? • Shock waves caused by dynamic events in the photosphere? • Magneto-hydrodynamical modes (and magnetic storms)?  In which way we can examine it? We need to observe AGB stars at different epochs ALSO in mid-IR!!  Simultaneous observations in near & mid IR could be fundamental to understand these phenomena.  Moreover, correlation with optical variability could be necessary. Optical and Infrared Wide-Field Astronomy in Antarctica

  20. Mid-IR Observations from Antarctica:Magellanic Clouds As mentioned before by Dolci (see talk) IRAIT : valid observations for fluxes > 0.5 Jy IRAIT will observe stars of the Magellanic Clouds down to the base AGB in mid-IR. A 4m IR telescope placed in Antarctica could study stars of the Magellanic Clouds down to the RGB. This telescope could also observe the AGB stars beyond the M31 group (see previous talk). Optical and Infrared Wide-Field Astronomy in Antarctica

  21. Mid-IR Observations from Antarctica:dSph Satellites of the Milky Way An IR 4m telescope placed in Antarctica will allow us also to study stars in the final phases of their evolution from all the Dwarf Spheroidal Satellites of the Milky Way, at very different metallicities. (For the dSphs we could observe at least the giants at the tip of the RGB phase). Optical and Infrared Wide-Field Astronomy in Antarctica

  22. Results with space-borne mid-IR observations:Observations Used…..  Surveys from the ground in near-IR: 2MASS/DENIS.  Observations in mid-IR (mainly through space-borne telescopes): • ISO (SWS) : 3-45 um • MSX : 8-21 um BUT A low number of sources is observed and usually only with a single observation. Optical and Infrared Wide-Field Astronomy in Antarctica

  23. Results with space-borne mid-IR observations:Post-AGB Stars Different variability types are well distinguished by IR colors. Guandalini et al. 2006 Kwok et al. 1999 Optical and Infrared Wide-Field Astronomy in Antarctica

  24. Results with ground-based mid-IR observations:Post-AGB Stars and TIRCAM2 Busso et al. 2006 Optical and Infrared Wide-Field Astronomy in Antarctica

  25. Results with space-borne mid-IR observations:Luminosity Of AGB Stars: C Stars Milky Way Magellanic Clouds Costa & Frogel 1996; Van Loon et al. 1999 Guandalini et al. 2006 Optical and Infrared Wide-Field Astronomy in Antarctica

  26. Results with space-borne mid-IR observations:Luminosity Of AGB Stars: S Stars Optical and Infrared Wide-Field Astronomy in Antarctica

  27. Results with space-borne mid-IR observations:HR Diagrams for C stars Guandalini et al. 2006 Marigo et al. Molec. Opac. ? Optical and Infrared Wide-Field Astronomy in Antarctica

  28. Results with ground-based mid-IR observations:HR Diagram for C stars Busso et al. 2006 Optical and Infrared Wide-Field Astronomy in Antarctica

  29. Results with space-borne mid-IR observations:HR Diagram for S stars S branch SC branch Optical and Infrared Wide-Field Astronomy in Antarctica

  30. Results with space-borne mid-IR observations:Mass Loss – IR Colors Guandalini et al. 2006 Optical and Infrared Wide-Field Astronomy in Antarctica

  31. Results with ground-based mid-IR observations:Mass Loss – IR Colors Guandalini et al. 2006 Busso et al. 2006 Optical and Infrared Wide-Field Astronomy in Antarctica

  32. Conclusions There is the need of understanding the final evolutionary phases of AGB sources (luminosity, mass loss…..):  the amount of the matter returned to the InterStellar Medium  chemical evolution  mass of the White Dwarfs Update of the photometrical analysis of these stars up to 40 um (beyond 20 um this might require new detectors). The future class of IR telescopes at Dome C can do studies like those shown here for the Local Group. Dome C might become THE place where stellar evolution gets clarified. Optical and Infrared Wide-Field Astronomy in Antarctica

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