Detection of the CCP (X 2  r ) Radical in IRC+10216: A New Interstellar Phosphorus-Containing Species DeWayne T. Halfen Steward Observatory, Arizona Radio Observatory, University of Arizona Dennis Clouthier Department of Chemistry, University of Kentucky Lucy M. Ziurys Departments of Chemistry and Astronomy, Steward Observatory, Arizona Radio Observatory, University of Arizona June 20, 2008

The Importance of Phosphorus Phosphorus key component of RNA, DNA (replication), ATP (metabolism), phospholipids (structure) Cosmically rare – 18 th most abundant element Concentrated in biology – 5 th most abundant Found in meteorites in the form of schreibersite (Fe,Ni) 3 P (Pasek & Lauretta 2005) DNA

CSE models also predict that P condenses into schreibersite (Fe,Ni) 3 P (Lodders & Fegley 1999)

In diffuse clouds, atomic measurements show that phosphorus not depleted onto grains (Lebouteiller et al. 2005) However in dense clouds, only one phosphorus-bearing species found – PN (Ziurys 1987; Turner & Bally 1987) Until very recently, only one phosphorus-containing species confirmed in circumstellar envelopes – CP (Guélin et al. 1990) PN: J = 2  1 Orion-KL Ziurys 1987 Milam et al Phosphorus in the ISM

In the last year, HCP and PN observed in IRC and CRL 2688 (Agúndez et al. 2007; Milam et al. 2008), and tentatively PH 3 (Tenenbaum & Ziurys 2008; Agúndez et al. 2008) –AGB star (IRC+10216) and Protoplanetary nebula (PPN: CRL 2688) Phosphorus Species in Carbon-rich Envelopes Milam et al PH 3 J K = 1 0  0 0 Tenenbaum & Ziurys 2008

In the last year, PO and PN detected in VY CMa (Tenenbaum, Woolf, & Ziurys 2007; Milam et al. 2008) Tenenbaum, Woolf, & Ziurys 2008 Are there more? Milam et al Phosphorus Species in Oxygen-rich Envelopes

–MW, MMW, and submm data –  = 1/2 and 3/2 spin-orbit ladders, e and f lambda-doublets recorded –Phosphorus hyperfine I(P) = 1/2 observed in MW and MMW regions Halfen, Sun, Clouthier, Ziurys 2008 Recent Laboratory Measurements of CCP CCP (X 2  r ) rotational spectrum measured by Halfen et al. (2008; FC02)

Spectroscopic Constants for CCP ParameterMMW B (18) D (35) H5.0(2.0) x p+2q50.018(17) (p+2q) D (11) (p+2q) H 5.93(82) x h (40) hDhD 0.834(16) d (27) rms0.036 Selected Rotational Frequencies of CCP (X 2  r :  = 1/2) JJ JFF F Parity obs obs - calc 1.5  2  1e  0e  1f  0f   2e  1e  2f  1f   10e  9e  10f  9f  20.5 a e a f  a e a f Rotational spectrum for  = 1/2 state measured down to 2 mm and at cm wavelengths Can very accurately predict 3 mm spectrum as well Accuracy: 1 part in

Why IRC ? –CP, HCP, PN, and tentatively PH 3 all found in this source –Many carbon-chain species, up to C 8 –Multiple analogous carbide molecules: SiC, SiC 2, CS, CCS Search for CCP in IRC Searched for CCP with ARO 12m on Kitt Peak at 2 and 3 mm KP 12m

Searched for four rotational transitions –Each transition split by lambda-doubling –Each transition observed for hours –Reached 3  noise level of mK –Lines only mK –Five out of the eight possible lines cleanly detected –Three other lines blended with known species –P hyperfine not resolved CCP conclusively detected Six P-bearing species in space Halfen, Clouthier, Ziurys 2008

Based on observed spectra, used model of Bieging & Tafalla (1993) to determine the abundance and distribution of HCP, PN, CP, and CCP in IRC (Milam et al. 2008; Halfen et al. 2008) Abundances and Distribution in IRC HCP and PN formed under equilibrium conditions near the star CP and CCP found in outer shell of the envelope –CCP less abundant, even further from star than CP

In CSEs, HCP parent species of CP and possibly CCP HCP + hv  CP + H CP + CCH  CCP + CH CP + C 3 H  CCP + CCH Outer envelope chemistry may be dominated by ion-molecule reactions CCP could also be formed from P + and HCCH P + predicted in outer envelope of IRC (Agúndez et al. 2007) P + + HCCH  HCCP + + H HCCP + + e   CCP + H CCP Formation in Circumstellar Envelopes

Richer phosphorus chemistry than in molecular clouds –Still only PN detected in dense gas Most of P could be depleted onto grains, i.e. in schreibersite –Contradicts results from diffuse clouds More P-containing molecules to be discovered in ISM & CSE Now 5 P-bearing species detected in the CSE of IRC % total phosphorus in IRC in molecules –Based on cosmic P abundance of 3 x IRC Molecule  s (″) N tot (cm -2 )f (X/H 2 ) PN361 x x HCP221 x x PH 3 41 x x CP26(shell)1 x x CCP80 (shell)1 x x Total9 x Summary of Phosphorus Molecules in IRC+10216

With new technology, more molecules could be found New ALMA Band 3 receiver at 3mm recently installed on the ARO 12m ~10 fold increase in sensitivity vs. old 3mm receiver 1.4 mK (3  ) after 15 hours New Discoveries with ALMA technology

Lucy Ziurys Dennis Clouthier Emmy Tenenbaum Ming Sun Robin Pulliam Lindsay Zack Jessica Dodd Gilles Adande NASA Astrobiology Institute NSF Astronomy and Astrophysics Postdoctoral Fellowship Acknowledgements