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

## TL;DR

This study investigates the magnetic field structure of Lynds 1340, especially RNO 8, using infrared polarimetry combined with archival data, revealing ordered magnetic fields and estimating their strength.

## Contribution

It provides the first detailed infrared polarimetric mapping of Lynds 1340's magnetic field, integrating multiple data sources for comprehensive analysis.

## Key findings

- Magnetic field strength in RNO 8 is approximately 42 microgauss.
- Polarisation vectors indicate an ordered magnetic field aligned with the galactic field.
- Dichroic extinction causes the observed polarisation, consistent with galactic magnetic field models.

## Abstract

This paper describes the polarisation study of a Lynds cloud, LDN 1340, $\alpha$ = 2h32m & $\delta$ = $73^{\circ} 00^\prime$ corresponding to galactic coordinates of $\ell=$ 130$^{\circ}$.07 $b=$ 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 & Polarimeter (NICSPol) 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 & 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.