Molecules, dust, and protostars in NGC3503

N.U. DURONEA; J. VASQUEZ; GISELA A. ROMERO; C. CAPPA; L. BRONFMAN; R. BARBÁ

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2014 vol. 565 p. 1 - 10

0004-6361

Aims. We are presenting here a follow-up study of the molecular gas and dust in the environs of the star forming region NGC3503.This study aims at dealing with the interaction of the Hii region NGC3503 with its parental molecular cloud, and also with the starformation in the region, that was possibly triggered by the expansion of the ionization front against the parental cloud.Methods. To analyze the molecular gas we use CO (J=2→1), 13CO (J=2→1), C18O (J=2→1), and HCN (J=3→2) line data obtainedwith the on-the-fly technique from the APEX telescope. To study the distribution of the dust, we make use of unpublished imagesat 870 μm from the ATLASGAL survey and IRAC-GLIMPSE archival images. We use public 2MASS and WISE data to search forinfrared candidate YSOs in the region.Results. The new APEX observations allowed the substructure of the molecular gas in the velocity range from ∼ −28 to −23 km s−1to be detailed imaged. The morphology of the molecular gas close to the nebula, the location of the PDR, and the shape of radiocontinuum emission suggest that the ionized gas is expanding against its parental cloud, and confirm the ?champagne flow? scenario.We have identified several molecular clumps and determined some of their physical and dynamical properties such as density, excitationtemperature, mass, and line width. Clumps adjacent to the ionization front are expected to be affected by the Hii region, unlikethose that are distant to it. We have compared the physical properties of the two kind of clumps to investigate how the moleculargas has been affected by the Hii region. Clumps adjacent to the ionization fronts of NGC3503 and/or SFO62 have been heated andcompressed by the ionized gas, but contrary to what were expected their turbulence is not different to those that are too distant to theionization fronts. We identified several candidate YSOs in the region. Their spatial distribution suggests that stellar formation mighthave been boosted by the expansion of the nebula.We discard the ?collect and collapse? scenario and propose alternative mechanismssuch as radiatively driven implosion or small-scale Jeans gravitational instabilities.