Laboratory and space spectroscopy of DCO⁺

¹ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy e-mail: caselli@arcetri.astro.it
² Dipartimento di Chimica “G. Ciamician”, Università di Bologna, via Selmi 2, 40126 Bologna, Italy e-mail: luca.dore@unibo.it

Received: 5 October 2004
Accepted: 16 December 2004

Abstract

The rotational spectra of and its two isotopomers and , produced in a negative glow discharge cell, have been recorded in the 137–792 GHz region, which includes lines from up to . The determined rotational and centrifugal distortion constants allow to predict the rotational spectrum up to 1000 GHz with an accuracy of 1 part in 10⁸ or better. This is important for kinematic studies of dense molecular cloud cores and for future far–infrared observations. We also report on the first detection of the hyperfine structure of the (1–0) line made at the IRAM 30 m antenna, toward the quiescent starless cloud core L1512, in the Taurus Molecular Cloud. We point out that this is the first observation of the hyperfine splitting due to the deuteron. This allowed us to quantify the effects of the hyperfine splitting on the line width determination; if the hyperfine structure is not taken into account in the line fit, the (1–0) line width is overestimated by a significant factor (2).