An Observational Investigation of the Identity of B11244 (l-C3H+/C3H-)

Brett A. Mcguire (1) , P. Brandon Carroll (1) , P. Gratier (2, 3) , Viviana Guzman Veloso (3) , Jerome Pety (3, 2) , Evelyne Roueff (4, 2) , Maryvonne Gerin (2) , Geoffrey A. Blake (1) , Anthony J. Remijan (5)

1 CALTECH - California Institute of Technology
2 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
3 IRAM - Institut de RadioAstronomie Millimétrique
4 LUTH (UMR_8102) - Laboratoire Univers et Théories
5 NRAO - National Radio Astronomy Observatory

Pety et al. have reported the detection of eight transitions of a closed-shell, linear molecule (B11244) in observations toward the Horsehead photodissociation region (PDR), which they attribute to the l-C3H+ cation. Recent high-level ab initio calculations have called this assignment into question; the anionic C3H- molecule has been suggested as a more likely candidate. Here, we examine observations of the Horsehead PDR, Sgr B2(N), TMC-1, and IRC+10216 in the context of both l-C3H+ and C3H-. We find no observational evidence of Ka = 1 lines, which should be present were the carrier indeed C3H-. Additionally, we find a strong anticorrelation between the presence of known molecular anions and B11244 in these regions. Finally, we discuss the formation and destruction chemistry of C3H- in the context of the physical conditions in the regions. Based on these results, we conclude there is little evidence to support the claim that the carrier is C3H-.

Mots clés: ISM: molecules; ISM: individual objects: Sagittarius B2(N) TMC-1 Horsehead PDR IRC+10216; astrochemistry; ISM: clouds

Domaines: Astrophysique galactique [astro-ph.GA]

Brett A. Mcguire, P. Brandon Carroll, P. Gratier, Viviana Guzman Veloso, Jerome Pety, et al.. An Observational Investigation of the Identity of B11244 (l-C3H+/C3H-). The Astrophysical Journal, 2014, 783, pp.36. ⟨10.1088/0004-637X/783/1/36⟩. ⟨hal-00992471⟩