12CO and 13CO J=3-2 observations toward N11 in the Large Magellanic Cloud

CELIS PEÑA, M.; PARON, S.; RUBIO, M.; HERRERA, C. N.; ORTEGA, M. E.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2019

0004-6361

After 30 Doradus, N11 is the second largest and brightest nebula in theLMC. This large nebula has several OB associations with bright nebulaeat its surroundings. N11 was previously mapped at the lowest rotationaltransitions of 12CO J=1-0 and 2-1, and in some particularregions pointings of the 13CO J=1-0 and 2-1 lines were alsoperformed. Using ASTE we mapped the whole extension of the N11 nebula inthe 12CO J=3-2 line, and three sub-regions in the 13CO J=3-2line. The regions mapped in the 13CO J=3-2 were selected based onthat they may be exposed to the radiation at different ways: a regionlying over the nebula related to the OB association LH10 (N11B), anotherone that it is associated with the southern part of the nebula relatedto the OB association LH13 (N11D), and finally a farther area at thesouthwest without any embedded OB association (N11I). We found that themorphology of the molecular clouds lying in each region shows somesignatures that could be explained by the expansion of the nebulae andthe action of the radiation. Fragmentation generated in a molecularshell due to the expansion of the N11 nebula is suggested. Theintegrated line ratios 12CO/13CO show evidences of selectivephotodissociation of the 13CO, and probably other mechanisms suchas chemical fractionation. The CO contribution to the continuum at 870 microns was directly derived. The distribution of the integrated lineratios 12CO J=3-2/2-1 show hints of stellar feedback in N11B andN11D. The ratio between the virial and LTE mass M_vir/M_LTE is higher than unity in all analyzed molecular clumps, whichsuggests that the clumps are not gravitationally bounded and may besupported by external pressure. A non-LTE analysis suggests that we aremapping gas with densities about a few 10^3 cm^-3.