NML Cyg The ARO 1 mm Survey of the Oxygen-rich Envelope of Supergiant Star NML Cygnus Jessica L. Edwards, Lucy M. Ziurys, and Nick J. Woolf The University of Arizona Departments of Chemistry and Astronomy The 66th Ohio State University International Symposium on Molecular Spectroscopy

Motivation Only one survey of an oxygen-rich circumstellar shell, VY Canis Majoris – Tenenbaum et al. 2010, ApJL, 720, L102 – Tenenbaum et al. 2010, ApJSS, 190, 348 Compare chemistries of similar objects, start determining what controls the molecular production in these envelopes NML Cyg is also a supergiant star, further, possibly higher mass loss rate

Observations Arizona Radio Observatory Sub-Millimeter Telescope 1.3 mm ALMA Type Receiver GHz Filterbanks, 1 GHz bandwidth, dual polarization 1σ r.m.s. noise level ~3 mK Variable IF from 4-8 GHz to avoid image contamination NML Cyg is up from 15-3 LST Total survey time ~ 840 hrs

NML Cygnus Oxygen rich supergiant, 40 M ʘ Distance ~1.7 kiloparsecs Mass loss rate x M ʘ yr -1 Similar to VY CMa, possibly higher mass loss rate Non-spherical CSE Schuster, Humphreys, & Marengo AJ 131, 603

215 SO 2 SO 217 SiO H2SH2S 216 SiO v=1 34 SO 217 H2SH2S SiO SiS v=1 SO 2 Na 37 Cl NML Cyg

254 SO 2 30 SiO SiS NS 282 SO 2 PN SO 2 Si 18 O + Si 34 S SO CN CS U 30 SiS NaCl v=1

Velocity Structure HCN SO 2 CS SiS and 30 SiO

Velocity Structure Pulliam, Edwards, and Ziurys, ApJ, submitted

VY CMa SO 2 PN SO 2 Si 18 O + Si 34 S NML Cyg Comparison with VY CMa NS SiS 30 SiO SO 2 NML Cyg VY CMa SO NML Cyg 13 CO Can not make direct comparisons yet, but there are clearly relative differences Weaker lines in NML Cyg for most molecules, exceptions SiS, 12 CO, 13 CO

CO NML Cyg SO 13 CO NML Cyg VY CMa Comparison with VY CMa

Molecular Inventory Molecules Detected in VY Canis Majoris COCSPNH2SH2SHCO + SiOCNPOHCNU-lines SiSNSAlOHNCH2OH2O SONaClAlOHSO 2 OH Molecules Detected in NML Cyg (so far) COCSPNH2SH2SHCO + SiOCNHCNU-lines SiSNSH2OH2O SONaClSO 2 OH HST image of VY CMa. Credit: NASA, ESA, and R. Humphreys Schuster, Humphreys, & Marengo 2006 AJ 131, 603

Results The survey is approximately 30% finished Species observed so far: 12 CO, 13 CO, 12 CN, 13 CN, SO, 34 SO, SO 2, SiS, 30 SiS, Si 34 S, SiO, 30 SiO, Si 18 O, H 2 S, NaCl, Na 37 Cl, CS, NS, PN 12 molecules, 1 unidentified line Complex velocity structure, varies for different molecules

Future Directions Finish the survey! (Fall 2011) Full molecular inventory Higher resolution observations, outflows Use a radiative transfer analysis to model abundances for NML Cyg and VY CMa Compare chemistry, investigate possible causes: mass loss, photodissociation regions, CO, mixing? Supergiants vs. AGB stars

Acknowledgements Dr. Ziurys, Dr. Woolf Dr. Emily Tenenbaum, Lindsay Zack The rest of the Ziurys Group Arizona Radio Observatory Engineers, Operators NASA and NSF for funding