Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Methyltriacetylene (Ch3C6H) Toward TMC-1: Presently, the Largest Detected Symmetric Top



A Remijan, J M. Hollis, Lewis E. Snyder, P R. Jewell, Francis J. Lovas


We report the detection of a new interstellar methylpolyyne, CH3C6H (methyltriacetylene) with the 100-m Green Bank Telescope (GBT). Ten spectral lines of this species were detected toward TMC-1: the K=0 and K=1 components of the 12,K-11,K, 13,K-12,K, 14,K-13,K, 15,K-14,K, and 16,K-15,K transitions. Also observed were the K=0 and K=1 components of the 6,K-5,K transition of CH3C4H. For both methylpolyynes, no higher energy K components were detected which is consistent with the 10 K kinetic temperature of the TMC-1 dark cloud. Moreover, radio spectral line data of the cyanopolyyne, methycyanopolyyne, and methylpolyyne carbon-chain sequences were studied and strong correlation were found among the values of the three different carbon-chain slopes when total column densities of sequence members are plotted against the number of carbon atoms in the carbon-chain. This result suggests that the formation chemistry for all these carbon-chain sequences is common and, as a consequence, successive carbon addition on grains is likely. The total column density of the next larger, undetected species in each of the three carbon chain sequences is predicted.
Astrophysical Journal


abundances, interstellar cloud, interstellar molecule, methyltriacetylene, microwave spectrum, radio astronomy


Remijan, A. , Hollis, J. , Snyder, L. , Jewell, P. and Lovas, F. (2006), Methyltriacetylene (Ch<sub>3</sub>C<sub>6</sub>H) Toward TMC-1: Presently, the Largest Detected Symmetric Top, Astrophysical Journal (Accessed April 21, 2024)
Created April 27, 2006, Updated October 12, 2021