The Missing Link of Sulfur Chemistry in TMC-1: The Detection of <i>c</i>-C<sub>3</sub>H<sub>2</sub>S from the GOTHAM Survey
Anthony J. Remijan, P. Bryan Changala, Ci Xue, Eric Yuan, Miya Duffy, Haley N. Scolati, Christopher N. Shingledecker, Thomas H. Speak, Ilsa R. Cooke, Ryan A. Loomis, Andrew M. Burkhardt, Zachary T. P. Fried, Gabi Wenzel, Andrew Lipnicky, Michael McCarthy, Brett A. McGuire
Abstract
Abstract We present the spectroscopic characterization of cyclopropenethione in the laboratory and detect it in space using the Green Bank Telescope Observations of TMC-1: Hunting Aromatic Molecules survey. The detection of this molecule—the missing link in understanding the C 3 H 2 S isomeric family in TMC-1—completes the detection of all three low-energy isomers of C 3 H 2 S, as both CH 2 CCS and HCCCHS have been previously detected in this source. The total column density of this molecule ( N T of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>5.7</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.61</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.65</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> </mml:msup> </mml:math> cm −2 at an excitation temperature of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>4</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>1.3</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> K) is smaller than both CH 2 CCS and HCCCHS and follows nicely the relative dipole principle (RDP), a kinetic rule of thumb for predicting isomer abundances that suggests that, all other chemistry among a family of isomers being the same, the member with the smallest dipole ( μ ) should be the most abundant. The RDP now holds for the astronomical abundance ratios of both the S-bearing and O-bearing counterparts observed in TMC-1; however, CH 2 CCO continues to elude detection in any astronomical source.