2006ApJ...643L.107M

We present the results of a new, wide-field, and broad-ranging survey for ¹²CO (1-0) emission regions in the nearest and brightest tidal structure: the Magellanic Bridge. We have detected seven sites of ¹²CO (1-0) emission using the NANTEN telescope in addition to the one detected previously. The integrated CO brightness for these detections ranges between 30 and 140 mK km/s, corresponding to an estimated molecular mass of (1-7)x10³ M_☉ [assuming the CO-to-H₂conversion factor (X-factor) of ∼1.4x10²¹/cm2 (K km/s)^–1]. The positions of the CO emission regions are generally coincident with sites of bright 100 µm emission, where I_100µm>2.6 MJy/sr, and have narrow line widths of ≲2 km/s, indicating gas in a cold and rather quiescent state. The velocity centroids of the CO spectra are generally consistent with those of the H I spectra, and we suggest that CO clouds are formed after the tidal encounter, rather than being extracted from the SMC. This is supported by the small typical lifetime of CO clouds, which is as short as ∼10⁷ yr and much less than the estimated 200 Myr age of the Bridge itself.