INTENSE MOLECULAR-EMISSION FROM THE LAGOON NEBULA, M8

The discovery is reported of the second strongest source of mm and sub mm wavelength CO line emission, towards M8, the Lagoon Nebula in Sagit tarius. The similar to 31 M. molecular core has dimensions similar to 0.2 x 0.3 pc and is centred on the O7V star Herschel 36 (H36), near th e Hourglass Nebula in the core of M8. Emission from the CO line wings extends to the north and south of the Hourglass, although a lack of ne ar-IR H-2 emission indicates that outflow activity is much less promin ent than in many active star-formation regions, and suggests that the CO line wings may trace the expanding edge of a cavity around H36. The molecular line data are compared with new near-IR narrow-band, contin uum-subtracted images in He I, H-2, and H+ (Br gamma) lines and archiv al HST emission-line images in H alpha, [OIII], and [SII]. The optical and near-IR data are found to be broadly consistent with previous pho to-ionisation models of the Hourglass, which is excited by H36. Howeve r, there are variations in the He I/Br gamma line ratio which are diff icult to explain.