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Late Type stars

PACS-ST Workshop, Jan 28/29, 2003, MPE Garching. Late Type stars. Franz Kerschbaum for the UNIVIE PACS team. AGB-Mass Loss Scenario. Kolenberg (1998) after Sedlmayr (1990). Fields of special interest. Physics/chemistry of the inner parts of nearby circumstellar envelopes (CSE)

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Late Type stars

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  1. PACS-ST Workshop, Jan 28/29, 2003, MPE Garching Late Type stars Franz Kerschbaum for the UNIVIE PACS team

  2. AGB-Mass Loss Scenario Kolenberg (1998) after Sedlmayr (1990) PACS-ST Workshop, Jan. 2003

  3. Fields of special interest • Physics/chemistry of the inner parts of nearby circumstellar envelopes (CSE) • chemistry, cooling(, dynamics by HIFI) • Mass loss mineralogy • Mass loss history • Detailed structure of spatially resolved nearby circumstellar envelopes (supp. by SPIRE) • Surveys for fossile shells in different environments PACS-ST Workshop, Jan. 2003

  4. Physics/chemistry of the inner parts of CSEs 2 • Molecular transitions sample different parts of CSEs because of different chemistry and excitation requirements • CSEs provide wide ranges of density, kin. temperature and radiation environments • Example of a 10-5 M/yr CSE: CO(1-0) samples typically a radius of 1017 cm, CO (5-4), (10-9), and (15-14) sample 61015, 21015, and 71014cm, respectively IRAM PdB PACS-ST Workshop, Jan. 2003

  5. Physics/chemistry of the inner parts of CSEs 2 • PACS (+SPIRE/HIFI) offer acomplete info about the physical conditions of the inner ML zones • (e.g. important coolants CO, H2O for O-rich and CO and HCN in C-rich CSEs) • For low resolution spectra PACS will have a much higher sensitivity than ISO, which was limited to high ML and/or very nearby objects • HIFIs high resolution spectra will allow studies of the dynamics of these (partially ML driving) zones Barlow et al. 1997 PACS-ST Workshop, Jan. 2003

  6. Mass loss mineralogy 1 • ISO caused a revolution in the field of astro-mineralogy of both low- and high-MLR objects • But most of these findings were in the SWS and not the LWS range! What to expect from PACS? Posch et al. 2002 PACS-ST Workshop, Jan. 2003

  7. Mass loss mineralogy 2 Features expected: • Forsterite (Mg2SiO4) at 69mm(sharp, dust thermometer!) • Calcite CaCO3 at 92.6mm • Crystalline water-ice at 61mm(broad, high S/N needed) • 62-63mm feature (Cands: Dolomite, Ankerite, Diopsid) • CaAl12O19 feature at 78mm Most ISO observation were really suffering S/N problems (esp. for the interesting low MLR-objects). The sensitivity of Herschel would be crucial but the short wave-length end of PACS is the clear limitation in this field! Sylvester et al. 1999 Bowey et al. 2002 Kemper 2002 PACS-ST Workshop, Jan. 2003

  8. Quantitative results:Spectroscopy (for mineralogy) • Low/intermediate-MLR objects in the solar neighbourhood: R Cas: 1.5h for 60-130µm at S/N>20 • High-MLR objects out to 1 kpc IRC+10216 like: 6h for 60-130µm at S/N>20 PACS-ST Workshop, Jan. 2003

  9. Mass loss history 1 • Currently it is not clear if AGB-ML is mainly a continuous process or episodic on timescales of ~103 yrs as a still small number of observations suggest • There may be interrelations between the ML history and the ML geometry • For Herschel PACS (+SPIRE) two main strategies seem interesting: • Observations of spatially resolved nearby circumstellar envelopes • Surveys for fossile shells in different environments Balick et al. 2000 PACS-ST Workshop, Jan. 2003

  10. Mass loss history 2 Izumiura et al. 1997 Olofsson et al. 2000 Sahai et al. 1998 Spatially resolved nearby detached envelopes • For the nearest objects PACS (+SPIRE) will deliver the detailed structures of the detached envelopes (resolving timescales of less than 1000 years) • Even very low ML episodes should be detectable (incl. ML modulations) • At 1 kpc the largest shells are still more or less filling the FOV. • PACS will (just) resolve some shells even at GC distances (beam at 85µm)! PACS-ST Workshop, Jan. 2003

  11. Quantitative results:Imaging (resolved) • Typ. cases: 75µm, S/N>20 r t (h) t10 (h) y. DSO: R Scl (350pc) 12" 0.07 0.08 o. DSO: TT Cyg (500pc), 35" 0.7 58 • The largest objects to expect have sizes of up to 10'! (U Ant (250pc), r=200" • SPIRE will allow for a extension towards longer wavelengths. PACS-ST Workshop, Jan. 2003

  12. Mass loss history 3 Surveys in different environments • PACS will detect most detached shell objects at GC distances • PACS (+SPIRE) should reach high ML stars in the MCs • The (relatively) large FOVs will allow mini-surveys in areas already covered by ISO at shorter wavelengths (GC, Bulge, LMC, SMC) • Combined CC-Diagrams allow to separate cold CSEs from e.g. molecular clouds • Such (quite expensive) mini-surveys have a multidisciplinary use! Cobe 1999 AURA 2000 PACS-ST Workshop, Jan. 2003

  13. Quantitative results:Imaging pointsources 1 PACS-ST Workshop, Jan. 2003

  14. Quantitative results:Imaging of pointsources 2 PACS-ST Workshop, Jan. 2003

  15. Quantitative results:Imaging of pointsources 3 • "normal" AGB stars feasible only out to GC, and at the shortest wavelengths • High-MLR AGB stars relatively easy out to MCs in full PACS range • Detached shell objects easy at GC and some possible at MCs at short wavelengths • Always only in combination with ISO-Surveys! PACS-ST Workshop, Jan. 2003

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