Discovery of SiCSi in IRC+10216: A missing link between gas and dust carriers of SiC bonds

TL;DR

This paper reports the first detection of SiCSi in space, revealing its role as a key SiC-bonded molecule in dust formation around the star CWLeo, bridging gas-phase chemistry and dust grain development.

Contribution

It presents the first astrophysical detection of SiCSi, with detailed spectroscopic analysis and implications for dust formation processes in carbon-rich stars.

Findings

112 spectral lines detected in CWLeo

SiCSi abundance comparable to SiC2

Emission originates from a 6 arcsecond region

Abstract

We report the discovery in space of a disilicon species, SiCSi, from observations between 80 and 350 GHz with the IRAM 30m radio telescope. Owing to the close coordination between laboratory experiments and astrophysics, 112 lines have now been detected in the carbon-rich star CWLeo. The derived frequencies yield improved rotational and centrifugal distortion constants up to sixth order. From the line profiles and interferometric maps with the Submillimeter Array, the bulk of the SiCSi emis- sion arises from a region of 6 arcseconds in radius. The derived abundance is comparable to that of SiC2. As expected from chemical equilibrium calculations, SiCSi and SiC2 are the most abundant species harboring a SiC bond in the dust formation zone and certainly both play a key role in the formation of SiC dust grains.