(Oxford University Press (OUP), 2000) Scappini, F.; Cecchi-Pestellini, C.; Codella, C.; Dalgarno, Alexander
HCO+ has been detected for the first time towards the star Cygnus OB2 No. 12 through emission of the 1−0 rotational transition at 89GHz. The CO(J=2−1) transition has also been observed. The observations are consistent with a model of dense regions embedded in a low-density clump gas. If actually present, the dense component would have an aggregate size L⩾1300au, in agreement with estimates of small-scale density fluctuations observed along diffuse lines of sight.
