Correlating the Interstellar Magnetic Field With Protostellar Jets and Its Sources

Abstract

This paper combines new CCD polarimetric data with previous information about protostellar objects in a search for correlations involving the interstellar magnetic field (ISMF). Specifically, we carried out an optical polarimetric study of a sample of 28 fields of 10 × 10 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 ISMF direction in each region. The results of the applied statistical tests are as follows. Concerning the alignment between the jet direction and the ISMF, the whole sample does not show alignment. There is, however, a statistically significant alignment for objects of Classes 0 and I. Regarding the ISMF 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 ISMF: 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.

Distortion of Magnetic Fields in BHR 71

“…There are many relatively small polarization vectors around the south-east corner and the south-west corner of the image, flowing from north-west to south-east. Reflecting this, the histogram of θ H for all sources has a peak fitted with a Gaussian function with a peak angle of 111 • ± 4 • (Figure 2), which is consistent with the optical polarimetry results (Targon et al 2011).…”

“…In this study, we use the value provided by Yang et al (2017). Targon et al (2011) conducted optical (R C band) polarimetry around the BHR 71 core. The obtained polarization angle (measured from north to east) was 102 • , indicating that the direction of the global magnetic fields is roughly parallel to the elongation axis of BHR 71 (∼ 130 • , see Figure 1, showing the elongation of the opaque region of BHR 71).…”

Bok globule CB 17: polarization, extinction and distance

“…whereas misalignment between the same has also been reported in several studies (e.g., Wolf et al 2003;Ménard and Duchéne 2004;Targon et al 2011;Krumholz et al 2013;. Based on MHD simulations, Matsumoto and Tomisaka (2004) and Matsumoto et al (2006) found that the alignment between the magnetic field direction and outflow direction depends on the strength of the magnetic field, i.e., stronger the magnetic field, better the alignment.…”

Magnetic field geometry of the large globule CB 34

“…Some study shows a good alignment of globule's magnetic field with outflow axis (e.g., Cohen et al (1984); Vrba et al (1986); Jones & Amini (2003)), whereas misalignment of magnetic field direction and outflow axis have been also reported (e.g. Wolf et al (2003); Ménard & Duchéne (2004); Hull et al (2013); Targon et al (2011);Soam et al (2015)). Soam et al (2015) reported that in IRAM 04191, the outflow is oriented almost perpendicular (∼ 84…”