Letter to the Editor

The rotational spectrum of protonated sulfur dioxide, HOSO⁺

¹ Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 USA
e-mail: vlattanzi@cfa.harvard.edu
² School of Engineering & Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138, USA
³ I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany

Received: 21 July 2011
Accepted: 19 August 2011

Abstract

Aims. We report on the millimeter-wave rotational spectrum of protonated sulfur dioxide, HOSO⁺.

Methods. Ten rotational transitions between 186 and 347 GHz have been measured to high accuracy in a negative glow discharge.

Results. The present measurements improve the accuracy of the previously reported centimeter-wave spectrum by two orders of magnitude, allowing a frequency calculation of the principal transitions to about 4 km s^-1 in equivalent radial velocity near 650 GHz, or one linewidth in hot cores and corinos.

Conclusions. Owing to the high abundance of sulfur-bearing molecules in many galactic molecular sources, the HOSO⁺ ion is an excellent candidate for detection, especially in hot cores and corinos in which SO₂ and several positive ions are prominent.