Correlating the interstellar magnetic field with protostellar jets and its sources

TL;DR

This study investigates the relationship between interstellar magnetic fields and protostellar jets using polarimetric data, revealing alignment in early star formation stages and correlations with magnetic field dispersion and extinction.

Contribution

It provides new polarimetric observations and statistical analysis linking magnetic field properties with protostellar object classes and environmental factors.

Findings

Alignment between jets and magnetic fields is significant for Classes 0 and I.

Regions with T Tauri stars show larger magnetic field dispersion.

Interstellar polarization peaks at A(V)=5 and correlates inversely with magnetic field dispersion.

Abstract

This article combines new CCD polarimetric data with previous information about protostellar objects in a search for correlations involving the interstellar magnetic field. Specifically, we carried out an optical polarimetric study of a sample of 28 fields of 10 X 10 arcmin^2 located in the neighborhood of protostellar jets and randomly spread over the Galaxy. The polarimetry of a large number of field stars is used to estimate both the average and dispersion of the interstellar magnetic field (ISMF) direction in each region. The results of the applied statistical tests are as follows. Concerning the alignment between the jet direction and the interstellar magnetic field, the whole sample does not show alignment. There is, however, a statistically significant alignment for objects of Classes 0 and I. Regarding the interstellar magnetic field dispersion, our sample presents values slightly larger for regions containing T Tauri objects than for those harboring younger protostars. Moreover the ISMF dispersion in regions containing high-mass objects tends to be larger than in those including only low-mass protostars. In our sample, the mean interstellar polarization as a function of the average interstellar extinction in a region reaches a maximum value around 3% for A(V) = 5, after which it decreases. Our data also show a clear correlation of the mean value of the interstellar polarization with the dispersion of the interstellar magnetic field: the larger the dispersion, the smaller the polarization. Based on a comparison of our and previous results, we suggest that the dispersion in regions forming stars is larger than in quiescent regions.