Scappini, F.Cecchi-Pestellini, C.Codella, C.Dalgarno, Alexander2017-02-222000Scappini, F., C. Cecchi-Pestellini, C. Codella, and A. Dalgarno. 2000. “Detection of HCO+ Towards Cygnus OB2 No. 12.” Monthly Notices of the Royal Astronomical Society 317 (1) (September 1): L6–L10. doi:10.1046/j.1365-8711.2000.03799.x.0035-8711http://nrs.harvard.edu/urn-3:HUL.InstRepos:30410804HCO+ 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.en-USstars: individual: Cygnus OB2 No. 12ISM: abundancesISM: cloudsISM: moleculesJournal Article2017-02-2210.1046/j.1365-8711.2000.03799.x