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Jinhua He ( 何金华 ) Yunnan Astronomical Observatory (YNAO) Collaborators ：

Jinhua He ( 何金华 ) Yunnan Astronomical Observatory (YNAO) Collaborators ： Prof . Ryszard Szczerba, Copernicus Astrnomical Center, Poland (NCAC) Dr. Tatsuhiko Hasegawa, ASIAA, Taipei Dr. Miroslaw Schmidt, Copernicus Astrnomical Center, Poland (NCAC).

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Jinhua He ( 何金华 ) Yunnan Astronomical Observatory (YNAO) Collaborators ：

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  1. Jinhua He (何金华) Yunnan Astronomical Observatory (YNAO) Collaborators： Prof. Ryszard Szczerba,Copernicus Astrnomical Center, Poland (NCAC) Dr. Tatsuhiko Hasegawa, ASIAA, Taipei Dr. Miroslaw Schmidt,Copernicus Astrnomical Center, Poland (NCAC) 2011-11-07, The Hong Kong Workshop on Evolved Stars and Astrophysical Masers CO and dust relation observed in post-AGB stage (preliminary) YNAO NCAC ASIAA

  2. Physical conditions in the circumstellar envelope during post-AGB evolution dust+gas (CO) UV ρd,ave Dust: M ρCO,ave CO gas: M τd TdM_ave Td(r) Tex,CO(r) τCO(r) TK(r) FIR ? ? Heating: dust-drag, ... Cooling: CO, ... lines, expansion, ... UV FCO2-1 ? ? log(r) How does (FCO2-1/FIR) ratio evolve with time? It is even more uncertain. But, study of it may tell us more about the post-AGB CSE evolution.

  3. The observation and results CO J=2-1: AROSMT 10m (2008) 58 high galactic latitude (|b|>15o) post-AGB stars available to SMT (Torun catalog of post-AGB stars, v.1). Detected 6 objects (rms~15mK @ d=1 MHz)。 DY Aql 19437-1104 19500-1709 V814 Her 17436+5003 Frosty Leo 09371+1212 07430+1115 89 Her 17534+2603 10/9/2014 3

  4. Data analysis Dust emission: IRAS12，25，60，100um。 Gas emission: CO 2-1. We do not estimate mass loss rate, but use RCO12=FCOint/F12μ；RCO25=FCOint/F25μ; C23= 2.5 log(F60μ/F25μ)→ T_dust Advantages： avoid the uncertainties in the mass loss formulae; avoid the uncertainties in distance. 10/9/2014 4

  5. CO/dust flux ratio of hgl post-AGB stars Fint(CO21) = ------------ F(25um) = 2.5 log(F60um/F25um) 10/9/2014 5

  6. Result-1 Except Frosty Leo and V887 Her, the other post-AGB stars tend to have RCO25≈const (?). To verify the constant RCO25, we resort to literature CO 2-1 data to form a larger post-AGB star sample. 10/9/2014 6

  7. CO/dust flux ratio of all post-AGB stars log(RCO25)=C23 Fint(CO21) = ------------ F(25um) = 2.5 log(F60um/F25um) 10/9/2014 7

  8. Result-2 Literature CO 2-1 data of more post-AGB stars support what we found in h.g.l. samples: RCO25≈const (group-I). Meanwhile, someother post-AGB stars seem to folow a log-linear trend: log(RCO25)=C23 (group-II)...Is it true? To confirm the log-linear trend, we propose to attest it in the context of AGB→post-AGB→PN evolutionary sequence. Literature CO 2-1 data of some AGB and PNe are compiled... 10/9/2014 8

  9. CO/dust flux ratio of AGB stars and PNe Fint(CO21) = ------------ F(25um) log(RCO25)=C23/10 = 2.5 log(F60um/F25um) 10/9/2014 9

  10. CO/dust flux ratio of AGB, post-AGB stars and PNe Fint(CO21) = ------------ F(25um) = 2.5 log(F60um/F25um) 10/9/2014 10 log(RCO23)=C23

  11. 25 60 12 RCO12→trace the post-AGB evolution trends Fint(CO21) = ------------ F(12um) 10/9/2014 11

  12. Result-3 C-stars have larger RCO25than O-rich AGB stars (AGB and SR, Lb); Redder PNe have larger RCO25; Early post-AGB stars (group I): RCO25≈ const, which is close to the dividing line between C- and O-rich AGB stars; Late-stage post-AGB stars (group II):log-linear relation log(RCO25)=C23, in accord with the trend of PNe. 10/9/2014 12

  13. Discussions The RCO25-C23 plot is a useful tool to reveal fast CO-dust co-evolution in post-AGB stage. group-I post-AGB stars: How do stars evolve from the large range of RCO25on AGB into the narrow range of RCO25on early post-AGB? group-II post-AGB stars: Why does the RCO25 ratio increase so much during post-AGB and PN stages? (over nearly 5 orders of magnitude!) ...however, ... Big issue: Selection effects of the samples?! 10/9/2014 13

  14. Completeness of the h.g.l. sample • In Torun Catalog of post-AGB stars (v.2) • Likely: all=212, h.g.l.=34, h.g.l.(SMT)=26 (76%) • RVTau: all=112, h.g.l.=22, h.g.l.(SMT)=20 • RCrB/eHe/LTP: all=72, h.g.l.=12, h.g.l.(SMT)=9 • Our 58 h.g.l. observed objects (selected from v.1) • Likely: all=25, detected=5; d_rate≈19% • RVTau: all=19, detected=0; d_rate=0% • RCrB/eHe/LTP: all=8, detected=0; d_rate=0% • Possible post-AGB: 6 (all non-det.) • Is the Torun Catalog complete? No answer.

  15. A complete compilation of literature CO 2-1 data of post-AGB stars • 174 entries of CO 2-1 observations (including non-detections) are found for 87 post-AGB stars. (up to Oct. 26, 2011) • 116 detection entries • 58 nondetection entries • 43/87 objects have CO 2-1 line detected. (compared with 49 literature data entries of 29 post-AGB stars in previous plots.) • By-product: also collected 930 entries of CO 2-1 line for 620 AGB, PNe, etc. • Analysis is going on...

  16. Dust+CO radiation transfer model Central star: 3 Msun, Bloecker (1995) Dust: Cir-sil, MRT code (Ryszard Szczerba) CO 2-1: thermal code + LVG code (Mirosloaw Schmidt) CSE: spherical AGB + post-AGB two-shell model. Mlr(pAGB) = Mlr(AGB) / 103

  17. Thanks! 谢谢！ 10/9/2014 17

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