Abstract:
In this work, we study the magnetic field morphology of selected star-forming clouds spread over the galactic
latitude (b) range −10° to 10°. The polarimetric observations of clouds CB24, CB27 and CB188 are conducted to
study the magnetic field geometry of those clouds using the 104 cm Sampurnanand Telescope (ST) located at
ARIES, Manora Peak, Nainital, India. These observations are combined with those of 14 further low latitude
clouds available in the literature. Most of these clouds are located within a distance range 140–500 pc except for
CB3 (∼2500 pc), CB34 (∼1500 pc), CB39 (∼1500 pc) and CB60 (∼1500 pc). Analyzing the polarimetric data of
17 clouds, we find that the alignment between the envelope magnetic field ( B
env q ) and galactic plane (GP) (θGP) of
the low-latitude clouds varies with their galactic longitudes (l). We observe a strong correlation between the
longitude (l) and the offset ( off B
env q = - ∣ ∣ q qGP ) which shows that B
env q is parallel to the GP when the clouds are
situated in the region 115° < l < 250°. However, B
env q has its own local deflection irrespective of the orientation of
θGP when the clouds are at l < 100° and l > 250°. To check the consistency of our results, the stellar polarization
data available in the Heiles catalog are overlaid on the DSS image of the clouds having mean polarization vector of
field stars. The results are almost consistent with the Heiles data. A systematic discussion is presented in the paper.
The effect of turbulence in the cloud is also studied which may play an important role in causing the misalignment
phenomenon observed between B
env q and θGP. We have used Herschel (Herschel is an ESA space observatory with
science instruments provided by European-led Principal Investigator consortia and with important participation
from NASA.) SPIRE 500 μm and SCUBA 850 μm dust continuum emission maps in our work to understand the
density structure of the clouds.
