A young stellar cluster within the RCW41 HII region: deep NIR photometry
  and Optical/NIR polarimetry
  The RCW41 star-forming region is embedded within the Vela Molecular Ridge,
hosting a massive stellar cluster surrounded by a conspicuous HII region.
Understanding the role of interstellar magnetic fields and studying the newborn
stellar population is crucial to build a consistent picture of the physical
processes acting on this kind of environment. We have carried out a detailed
study of the interstellar polarization toward RCW41, with data from an optical
and near-infrared polarimetric survey. Additionally, deep near-infrared images
from the NTT 3.5m telescope have been used to study the photometric properties
of the embedded young stellar cluster, revealing several YSO's candidates. By
using a set of pre-main sequence isochrones, a mean cluster age in the range
2.5 - 5.0 million years was determined, and evidence of sequential star
formation were revealed. An abrupt decrease in R-band polarization degree is
noticed toward the central ionized area, probably due to low grain alignment
efficiency caused by the turbulent environment and/or weak intensity of
magnetic fields. The distortion of magnetic field lines exhibit a dual
behavior, with the mean orientation outside the area approximately following
the borders of the star-forming region, and directed radially toward the
cluster inside the ionized area, in agreement with simulations of expanding HII
regions. The spectral dependence of polarization allowed a meaningful
determination of the total-to-selective extinction ratio by fittings of the
Serkowski relation. Furthermore, a large rotation of polarization angle as a
function of wavelength is detected toward several embedded stars.
