Quantitative Characterization of Tori in Evolved Stars – A possible observational project on evolved stars with ALMA Tatsuhiko Hasegawa (ASIAA) 2010 February ALMA-T Users Workshop
1.Summary 2.An evolution scenario for (post-)AGB stars and (pre-)planetary nebulae 3.Evidence of torus and jet developments at the end of AGB phase. 4.Difficulties for quantitative descriptions of the torus developments. 5.Straw man target list. Observing line. 6.Detection feasibility of expanding tori. Demonstrations of detections with SMA. 7.Dynamical times of tori and jets – This is the best we have. We need more points with better angular resolutions. 8.List of theoretical explanations.
Summary Resolving the torus structures in 20 – 30 (post-)AGB stars and (pre-)planetary nebulae in the CO(2-1 or 3-2) line with a 0.1 – 0.01 arcsecond resolution with ALMA to determine the basic physical parameters of the tori [R_in, R_out, h_z, V(expansion), M(torus), dynamical time ]. Quantitatively describing the formation and evolution of the torus structures in the evolved stars from the sample. Taking a census of deviations from the axial symmetry and radial expansion of the torus-like structures. How common are the tori among the evolved stars ? Providing constraints to the theorists.
Fong et al (ApJ, 652, 1626) – Evolved stars, Pre-planetary nebulae, and Planetary nebulae in HR diagram
CO, H2 HI, C+, OI H+, C+, O+ AGB phase (Mira variables) C/O > 1 (carbon stars) C/O < 1 (M type stars) C/O ~ 1 (S stars) Pre-Planetary Nebula Young Planetary Nebula Evolved Planetary Nebula M* (main seq) = 0.8 – 8 M_sun V(expansion) ~ 15 km/s
R 2 = 20,000 AU = 0.1 pc R 1 = 250 AU R * = 2.5 AU Circumstellar Envelope Transition Zone Glassgold 1996, ARAA, 34, 241. Omont 1991, NATO ASI, p171. Interstellar UV radiation V exp V exp = 15 km/s 1'' d = 200 pc case Photosphere Tk =500 K 2000 K 10 K
Planetary Nebula NGC 6302 HST image 30’’
Planetary Nebula NGC 7027 Central star HII region ( R = 5 ” ) Molecules (CO, R = 35 ” ) Dust
Zhang & Kwok 1998 ApJS, 117, 341
Fong et al. (2006) BIMA CO(1-0) vs HST and mid-IR Kwok et al (ApJ, 544, L149) IRAS –3046
O-rich starsD (pc) C-rich starsD (pc) R Dor 70 IRC pc HD kpcCIT 6380 pc IRC ?Y Cvn300 pc RW Lmi390 pc RX Boo ?1.7 kpc R Leo –3046 TX Cam (SMA obs) I K Tau VY CMa VX Sgr –3224 NML Cyg 3400 ?17441–2411 Mira HD ?1 kpcTT Cyg Her1 kpcCL Mon770 Provisional list of evolved stars for a torus survey with ALMA
–10 km/s channel map +10 km/s channel map 0 km/s channel map RA DEC RA DEC Velocity RA
NGC HCO+(3–2). SMA. Huang et al. (2010, submitted)
Gruis CO(2–1) SMA Chiu et al ApJ, 645, 605
Huggins 2007, ApJ, 663, 342 Torus ejection periodJet launch SMA
TABLE 2 Jet-Torus Scenarios (Huggins 2007, ApJ, 663, 342) Magnetic wind from single star ……………………… Jets and torus ? Primary mass loss + companion accretion disk O Discrete torus ejection ? Companion accretion disk + CE ejection ………………… Wrong sequence Common Envelope ejection + magnetic polar wind O Jet lag ? (Common Env.) magnetic polar + equatorial explosion O Jet lag ? (CE) primary accretion disk + late nebula ejection ……… Wrong sequence Common Env. partial ejection + primary accretion disk O Jet lag ? CE ejection + post-CE primary accretion disk (RLOF) Timescale too long ?