Magnetic fields in cometary globules – IV. LBN 437

Abstract

We present results of our R-band polarimetry of a cometary globule, LBN 437 (Gal 96-15, ℓ = 96◦, b = −15°), to study the magnetic field geometry of the cloud. We estimated a distance of 360 ± 65 pc to LBN 437 (also one additional cloud, CB 238) using a near-IR photometric method. The foreground contribution to the observed polarization 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 ionization radiation from the same exciting source that caused the cometary shape of the cloud. The orientation of the outflow from the Herbig A4e star, LkHα 233 (or V375 Lac), located at the head of LBN 437, is found to be parallel to both the initial (prior to the ionizing source was turned on) ambient magnetic field (inferred from a star HD 214243 located just in front of the cloud) and the Galactic plane.