Discovery of two new magnesium-bearing species in IRC+10216: MgC3N and MgC4H
Journal article, 2019

We report on the detection of two series of harmonically related doublets in IRC +10216. From the observed frequencies, the rotational constant of the first series is B = 1380.888 MHz and that of the second series is B = 1381.512 MHz. The two series correspond to two species with a (2)Sigma electronic ground state. After considering all possible candidates, and based on quantum chemical calculations, the first series is assigned to MgC3N and the second to MgC4H. For the latter species, optical spectroscopy measurements support its identification. Unlike diatomic metal-containing molecules, the line profiles of the two new molecules indicate that they are formed in the outer layers of the envelope, as occurs for MgNC and other polyatomic metal-cyanides. We also confirm the detection of MgCCH that was previously reported from the observation of two doublets. The relative abundance of MgC3N with respect to MgNC is close to one while that of MgC4H relative to MgCCH is about ten. The synthesis of these magnesium cyanides and acetylides in IRC +10216 can be explained in terms of a two-step process initiated by the radiative association of Mg+ with large cyanopolyynes and polyynes followed by the dissociative recombination of the ionic complexes.

stars: carbon

line: identification

stars: individual: IRC+10216

circumstellar matter


molecular data


J. Cernicharo

Spanish National Research Council (CSIC)

C. Cabezas

Spanish National Research Council (CSIC)

J. R. Pardo

Spanish National Research Council (CSIC)

M. Agundez

Spanish National Research Council (CSIC)

C. Bermudez

Spanish National Research Council (CSIC)

Luis Velilla Prieto

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

F. Tercero

Ctr Desarrollos Tecnol

J. Lopez Perez

Ctr Desarrollos Tecnol

J. D. Gallego

Ctr Desarrollos Tecnol

J. P. Fonfria

Spanish National Research Council (CSIC)

G. Quintana-Lacaci

Spanish National Research Council (CSIC)

M. Guelin

Institut de Radioastronomie Millimétrique (IRAM)

Y. Endo

National Chiao Tung University

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 630 L2

Subject Categories

Astronomy, Astrophysics and Cosmology





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