The molecular environment of the pillar-like features in the H ii region G46.5–0.2

ORTEGA, M. E.; RUBIO, M.; CELIS PEÑA, M.; PETRIELLA, A.; CELIS PEÑA, M.; PETRIELLA, A.; PARON, S.; FARIÑA, C.; ASHLEY, R. P.; PARON, S.; FARIÑA, C.; ASHLEY, R. P.; ORTEGA, M. E.; RUBIO, M.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2017 vol. 470 p. 4662 - 4670

0035-8711

At the interface of H ii regions and molecular gas, peculiar structuresappear, some of them with pillar-like shapes. Understanding their originis important for characterizing triggered star formation and the impactof massive stars on the interstellar medium. In order to study themolecular environment and influence of radiation on two pillar-likefeatures related to the H ii region G46.5-0.2, we performed molecularline observations with the Atacama Submillimeter Telescope Experimentand spectroscopic optical observations with the Isaac Newton Telescope.From the optical observations, we identified the star that is excitingthe H ii region as spectral type O4-6. The molecular data allowed us tostudy the structure of the pillars and an HCO+ cloud lyingbetween them. In this HCO+ cloud, which has no well-defined12CO counterpart, we found direct evidence of star formation:two molecular outflows and two associated near-IR nebulosities. Theoutflow axis orientation is perpendicular to the direction of theradiation flow from the H ii region. Several Class I sources are alsoembedded in this HCO+ cloud, showing that it is usual thatyoung stellar objects (YSOs) form large associations occupying a cavitybounded by pillars. On the other hand, it was confirmed that theradiation-driven implosion (RDI) process is not occurring in one of thepillar tips.