A New Molecular Perspective of the Planetary Nebulae M1-59, Na2, Hu1-1, and M4-17

Recent observations have revealed the presence of a variety of polyatomic species in over 30 planetary nebulae (PNe). These results have challenged prevailing chemical models which predict that PN are chemically depleted via ultraviolet radiation. In order to further investigate the molecular inventory of PNe, additional observations have been conducted towards four objects: Hu 1-1, M4-17, M1-59, and Na2. For these measurements, the Arizona Radio Observatory (ARO) Submillimeter Telescope, at 1mm in wavelength, and the Institut de radioastronomie millimétrique (IRAM) 30m antenna telescope at 2mm, were employed. The nebulae, selected for their known HCO⁺ and/or HCN content, exhibit diverse aspherical morphologies and ages. For example, Hu1-1 is elliptical while M4-17 is bipolar; Na2 is very old at ~ 28,000 years old. These observations have led to the first detections of CS: J = 3 →2 and J = 5 → 4, CCH: N_J = 2_5/2 →1_3/2, and CN: N_J = 2_5/2 → 1_3/2 towards Hu1-1, M1-59 and M4-17. Furthermore, c-C₃H₂ J_Ka,Kc = 3_1,2 →2_2,1 was observed towards both Hu1-1 and M4-17. These detections are further indications of complex chemistry in PNe. The fractional abundances of CS were determined to be f ~ 5.2×10^-9, relative to H₂, in Hu1-1, and 1.0×10^-8 and 8.0×10^-9 in M4-17 and M1-59 respectively- a factor of ten less than the abundance of HCO⁺ and HCN in these sources. In contrast, for CCH, fractional abundances are 2.7×10^-7, 7.9×10^-7, and 3.1×10^-7 in M1-59, Hu1-1, and M4-17 respectively. This data along with isotope ratios and additional molecular abundances will be presented.