The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Comparative Chemistry of Planetary Nebulae: Jessica L. Edwards Lucy M. Ziurys The University of Arizona Departments of Chemistry and Astronomy The Role of the Carbon to Oxygen Ratio

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 What is a Planetary Nebula? Planetary Nebulae (PNe) are one of the final stages of a star’s life As stars age, nucleosynthesis becomes more unstable causing these evolved stars to experience significant mass loss Creates molecule-rich circumstellar envelope Carbon-rich (C/O>1), Oxygen-rich (C/O<1), or in between (C≈O), depending on the stellar mass Not this

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 What is a Planetary Nebula? Carbon-rich stars (C/O>1) are formed via the triple- alpha process More massive (≈4-8 M ʘ ) stars can undergo hot- bottom burning which activates the CNO cycle and lowers the C/O ratio to near 1, or even convert the star back to an Oxygen-rich object (C/O<1)

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 What is a Planetary Nebula? The C/O ratio determines the types of molecules observed in these circumstellar envelopes Circumstellar envelope detaches, material flows outward, and becomes a planetary nebula (UV radiation) This!

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Molecular Studies of PNe Photo courtesy: Dave Harvey Every frequency range available on both of the Arizona Radio Observatory Telescopes from 65 GHz – 720 GHz >2,500 hours of observing time ARO Band 9 Receiver

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 “It’s the ciiiiiirrrcle of liiiiiife!”

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 ALMA Prototype Antenna!!!

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Molecular Studies of PNe The New Arizona Radio Observatory 12-meter!

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Planetary Nebulae Studied Multiple transitions of CO, CS, and HCO + in K4-47, NGC 6537, M2-48, NGC 6720 (The Ring), and NGC 6853 (The Dumbbell) More in depth studies of NGC 6537 (The Red Spider) and M2-48 Map of HCO + J = 1  0 across NGC 6853 Maps of CO J = 4  3 and J = 3  2 in NGC 6537

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Spectra! ISMS 2010, WG04 ISMS 2011, TF11 ISMS 2012, WH09

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Edwards, Cox, & Ziurys 2014, ApJ, in print HCN,CN, HNC CS HCO + CO Redman et al. 2003

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 More in depth investigations… Finally starting to delve further into the chemistry of PNe beyond archetypical molecules like CO, CN, HCN, HCO + Beginning to see a more complex chemical inventory When comparing these inventories, we found something interesting: Carbon-rich, Oxygen-rich, and intermediate PNe, based off of their molecular inventory

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 A Carbon-rich Planetary Nebula One of the best studied PNe is carbon- rich NGC 7027 (700 years) ARO telescopes CO, CN, CCH, C 3 H 2, HCN, HCO +, HC 3 N, N 2 H + (Zhang et al. 2008) LACK of CS and HNC

NGC 6537 (The Red Spider) High excitation, C/O ~0.95 (1,600 years old) The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 An Intermediate Planetary Nebula Edwards & Ziurys 2013, ApJ, 770, L5

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 CO, CN, HCN, HNC, CCH, CS, SO, H 2 CO, HCO +, N 2 H + and numerous 13 C isotopologues An Intermediate Planetary Nebula Edwards & Ziurys 2013, ApJ, 770, L5 NGC 6537 (The Red Spider) High excitation, C/O ~0.95 (1,600 years old)

M2-48, Middle-aged at ~4,800 years, C/O ? The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 An Oxygen-rich Planetary Nebula? Edwards & Ziurys, in preparation ISMS 2013, FA04

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 M2-48, Middle-aged at ~4,800 years, C/O ? CO, CN, HCN, HNC, CS, SO, SO 2, SiO, HCO +, N 2 H + and numerous 13 C isotopologues An Oxygen-rich Planetary Nebula? ISMS 2013, FA04 Edwards & Ziurys, in preparation

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Abundances Models don’t predict this amount of chemical content Now we are beginning to have enough information to see some chemical trends Seeing fossil molecules from the AGB phase Molecular Abundances in Planetary Nebulae MoleculeM2-48Red SpiderNGC 7027 CO 1.0 x × CO 8.3 × × C 18 O 1.5 × × CN 3.8 x × × CN 1.9 x × … HCN 1.2 x × × H 13 CN 4.0 x × × HNC 4.7 x × < 4.1 × HN 13 C 1.8 x × … CCH × × CS 2.7 x × < 5.5 × SO 2.0 x × … H 2 CO × < 1.3 × HCO x × × SiO2.4 x SO x N2H+N2H+ 9.8 x × × c-C3H2c-C3H2 -< 1.1 × × 10 -9

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Insight into the Progenitor Star? Initial PPN chemistry, then freezout? C>O C≈O C<O

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Insight into the Progenitor Star? Use molecular abundances to determine isotope ratios M2-48 CNO equilibrium abundance value (~3.4) of 12 C/ 13 C are along with high nitrogen content are indicative of hot- bottom burning

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Insight into the Progenitor Star? Use molecular abundances to determine isotope ratios CNO equilibrium abundance value (~3.4) of 12 C/ 13 C are along with high nitrogen content are indicative of hot- bottom burning NGC 6537

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Insight into the Progenitor Star? NGC 6537  12 C/ 13 C from HCN and HNC are 3.5 and 2.4, respectively M2-48  12 C/ 13 C from HCN, HNC, and HCO + are 3.0, 2.6 and 4.5, respectively Observational evidence of HBB HBB occurs in stars with >4 M ʘ so the combination of these things may also help ascertain progenitor star mass! (CNO equilibrium abundance value ~3.4)

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Conclusions Planetary Nebulae are rich in molecular content Use molecular observations to help classify the progenitor star Carbon/Oxygen ratio Nucleosynthetic pathways (HBB) Stellar Mass

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Acknowledgements Dr. Ziurys The rest of the Ziurys Group ARO Engineers, Operators, Staff NASA and NSF for funding

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014 Table 2. Molecular Abundances in M2-48 MoleculeT Kin (K)n(H 2 ) (cm -3 )N(cm -2 ) a f(X) a,b CO c × × × CN55 d 2.9 × 10 5 e 1.7 × × CN55 d 2.9 × 10 5 e 8.7 × × HCN55 d 5.6 × × × H 13 CN55 d 5.5 × × × HNC55 d 3.3 × × × HN 13 C55 d 4.4 × × × SiO559.0 × × × SO55 d 3.1 × × × SO 2 55 d 9.5 × × × CS c × × × HCO + c 55 d 1.3 × × × H 13 CO + 55 d 1.3 × 10 5 f 1.1 × × N2H+N2H+ 55 d 5.6 × 10 5 g 4.4 × × CCH55 d 2.9 × 10 5 e < 3.2 × < 7.1 × SiS55 d 2.9 × 10 5 e < 3.8 × h < 8.4 × H 2 CO55 d 2.9 × 10 5 e < 7.7 × h,i < 1.7 × a Assuming a source size of ~20''×30''; see text b Assuming CO/H 2 ~ ; see text c From Edwards, Cox, & Ziurys (2014) d Fixed to value from CS and SiO fit e Fixed to value from CS fit f Fixed to value from HCO + fit g Fixed to value from HCN fit h Assuming ΔV 1/2 ~33 km/s i Assuming an ortho to para ratio of ~3

The 69 th International Symposium on Molecular Spectroscopy June 19, 2014