Discovery of two metallic cyanoacetylides in IRC+10216: HMgCCCN and NaCCCN;

We report on the detection of a series of six lines in the ultra-deep Q-band integration towards IRC +10216 carried out with the Yebes 40 m telescope, which are in harmonic relation with integer quantum numbers J(u) from 12 to 18. After a detailed analysis of all possible carriers, guided by high-level quantum chemical calculations, we conclude that the lines belong to HMgCCCN, named hydridomagnesium cyanoacetylide. The rotational temperature and column density derived for HMgCCCN are 17.1 +/- 2.8 K and (3.0 +/- 0.6) x 10(12) cm(-2), respectively. The observed abundance ratio between MgCCCN and HMgCCCN is approximately three. In addition, we report the discovery in space, also towards IRC +10216, of sodium cyanoacetylide, NaCCCN, for which accurate laboratory data are available. For this species we derived a rotational temperature of 13.5 +/- 1.7 K and a column density of (1.2 +/- 0.2) x 10(11) cm(-2).

Automated summary

We detected a series of six lines in the ultra-deep Q-band integration towards IRC +10216, which are in harmonic relation with quantum numbers J(u) from 12 to 18. The lines are identified as HMgCCCN based on quantum chemical calculations. The rotational temperature and column density of HMgCCCN are determined as 17.1 +/- 2.8 K and (3.0 +/- 0.6) x 10(12) cm(-2) respectively. Additionally, we discovered sodium cyanoacetylide, NaCCCN, in space towards IRC +10216, and determined the rotational temperature and column density as 13.5 +/- 1.7 K and (1.2 +/- 0.2) x 10(11) cm(-2).