Title: The Lagoon Nebula and its Vicinity Authors: N. F. H. Tothill (U. Exeter, UK), Marc Gagné (West Chester U., USA), B. Stecklum (Tautenburg, Germany), M. A. Kenworthy (U. Arizona, USA)
The Lagoon Nebula is an HII region in the Sagittarius Arm, about 1.3 kpc away, associated with the young (1-3 Myr) open cluster NGC 6530, which contains several O stars and several dozen B stars. Lower-mass cluster members, detected by X-ray and H-alpha emission, and by near-IR excess, number more than a thousand. Myr-old star formation is traced by the optically-visible HII region and cluster; observations of infrared and submillimetre-wave emission, and of optical emission features, indicate ongoing star formation in several locations across the Lagoon. The most prominent of these are the Hourglass Nebula and M8E. Submillimetre-wave observations also reveal many clumps of dense molecular gas, which may form the next generation of stars. The complex structure of the region has been shaped by the interaction of the underlying molecular gas with multiple massive stars and episodes of star formation. NGC 6530 is the oldest component, with the newest stars found embedded in the molecular gas behind the cluster and at its southern rim. A degree to the east of the Lagoon, Simeis 188 is a complex of emission and reflection nebulae, including the bright-rimmed cloud NGC 6559; the presence of H-alpha emission stars suggests ongoing star formation.
Title: Geysers in the Lagoon: new Herbig-Haro objects in M8 Authors: Rodolfo H. Barbá (1), Julia I. Arias (1,2) ((1) Departamento de Física, Universidad de La Serena, Chile (2) Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Argentina)
Aims: We search for direct evidence of ongoing star formation by accretion in the Lagoon Nebula (M8), using optical wide-field narrow-band imaging obtained at La Silla Observatory. Methods: We examine [SII] and Halpha images for line-emission features that could be interpreted as signatures of outflow activity of the exciting sources. Results: We discover five new Herbig-Haro objects, study in detail their morphology and attempt to identify their potential driving sources among the population of T Tauri stars and embedded sources in the surroundings. Conclusions: The results reported here conclusively demonstrate the existence of very young stars going through the accreting phase in the M8 region.
The Lagoon Nebula also known as M8, is visible even without binoculars towards the constellation of Sagittarius. The energetic processes of star formation create not only the colours but the chaos.
The red-glowing gas results from high-energy starlight striking interstellar hydrogen gas. The dark dust filaments that lace M8 were created in the atmospheres of cool giant stars and in the debris from supernovae explosions. This spectacular portion of the Lagoon Nebula was created in scientifically-assigned colours from light emitted in very specific colours by hydrogen, silicon, and oxygen. The light from M8 we see today left about 5000 years ago. Light takes about 50 years to cross this section of M8.