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Late Type stars

The PACS-ST Workshop held in Garching on January 28-29, 2003, focused on the physics and chemistry of circumstellar envelopes (CSE) of late-type stars, particularly regarding mass loss phenomena. This workshop presented observational strategies and results concerning the detailed structure and dynamics of nearby CSEs using PACS and SPIRE instruments. Key topics included mass loss mineralogy, historical patterns of mass loss, and the implications of these processes on our understanding of AGB stars. The findings are essential for advancing the field of astro-mineralogy and the study of stellar evolution.

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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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