Infrared polarisation study of Lynds 1340: A case of RNO 8

Abstract

This paper describes the polarisation study of a Lynds cloud, LDN 1340, \(\alpha = 2\)h32m and \(\delta = 73^{\circ } 00^\prime \) corresponding to galactic coordinates of \(\ell = 130^{\circ }.07\) and \(b=\) 11\(^{\circ }.6\), with emphasis on the RNO 8 area. The cloud has been observed using the 1.2 m telescope at Mt. Abu Infrared Observatory, in the infrared wavelength band using the Near-Infrared Camera, Spectrograph and Polarimeter instrument. The polarimetric observations were used to map the magnetic field geometry around the region. We combined our measurements with archival data from the 2MASS and WISE surveys. The Gaia EDR3 and DR3 data for the same region were used for distance, proper motion, and other astrophysical information. The analysis of the data reveals areas with ordered polarisation vectors in the region of RNO 8. The position angle measurements reveal polarisation due to dichroic extinction which is consistent with the Galactic magnetic field. The magnetic field strength was calculated for the RNO 8 region using the Chandrashekhar–Fermi method and the value estimated is \(\sim \)42 \(\mu \)G.