Magnetic fields in cometary globules - IV. LBN 437

Abstract

We present results of our $R-$band polarimetry of a cometary globule, LBN 437 (Gal96-15, $\ell$ $=$ 96$\degree$, \textit{b} $=-15\degree$), to study magnetic field geometry of the cloud. We estimated a distance of $360\pm65$ pc to LBN 437 (also one additional cloud, CB 238) using near-IR photometric method. Foreground contribution to the observed polarisation values was subtracted by making polarimetric observations of stars that are located in the direction of the cloud and with known distances from the Hipparcos parallax measurements. The magnetic field geometry of LBN 437 is found to follow the curved shape of the globule head. This could be due to the drag that the magnetic field lines could have experienced because of the ionisation radiation from the same exciting source that caused the cometary shape of the cloud. The orientation of the outflow from the Herbig A4e star, LkH$\alpha$ 233 (or V375 Lac), located at the head of LBN 437, is found to be parallel to both the initial (prior to the ionising source was turned on) ambient magnetic field (inferred from a star HD 214243 located just in front of the cloud) and the Galactic plane.