Multiply-deuterated species in prestellar cores^*

¹ Physics Department, The University, Durham DH1 3LE, UK
² IAS, Université de Paris-Sud, 92405 Orsay Cedex, France
³ LUTH, Observatoire de Paris, 92195 Meudon Cedex, France
⁴ INAF, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy

Received: 14 June 2004
Accepted: 5 August 2004

Abstract

We have studied the ortho, para, and, in the case of D, meta forms of the multiply-deuterated isotopes of H, under physical conditions believed to be appropriate to pre-protostellar cores. As deuterons have integral nuclear spin, , Bose-Einstein statistical laws apply. Having extended the network of chemical reactions used in our previous study (Walmsley et al. [CITE]), we have calculated the population densities of ortho- and para-D₂H⁺ and of ortho- and meta-D. In the former case, comparison is made with the recent observations of para-D₂H⁺ in the prestellar core 16293E (Vastel et al. [CITE]). Using radiative transition probabilities computed by Ramanlal & Tennyson ([CITE]), we have predicted the intensities of the near infrared vibrational transitions of the deuterated isotopes of H. Many of these transitions can be observed, in absorption, only from above the Earth's atmosphere, but some might be detectable through atmospheric windows.