G141.2+5.0, A NEW PULSAR WIND NEBULA DISCOVERED IN THE CYGNUS ARM OF THE MILKY WAY

Abstract

We report the discovery of the new pulsar wind nebula (PWN) G141.2+5.0 in data observed with the Dominion Radio Astrophysical Observatory's Synthesis Telescope at 1420 MHz. The new PWN has a diameter of about 3.5', which translates at a distance of 4.0 kpc to a spatial extent of about 4 pc. It displays a radio spectral index of $\alpha\approx -0.7$, similar to the PWN G76.9+1.1. G141.2+5.0 is highly polarized up to 40% with an average of 15% in the 1420 MHz data. It is located in the centre of a small spherical HI bubble, which is expanding at a velocity of 6 km/s. The bubble's systemic velocity is -53 km/s and could be the result of the progenitor star's mass loss or the shell-type SNR created by the same supernova explosion in a highly advanced stage. The systemic velocity of the bubble shares the velocity of HI associated with the Cygnus spiral arm, which is seen across the 2nd and 3rd quadrants and an active star-forming arm immediately beyond the Perseus arm. A kinematical distance of 4+/-0.5 kpc is found for G141.2+5.0, similar to the optical distance of the Cygnus arm (3.8+/-1.1 kpc) and its kinematic HI distance (4.4+/-0.6 kpc). G141.2+5.0 represents the first radio PWN discovered in 17 years and the first SNR discovered in the Cygnus spiral arm, which is in stark contrast with the Perseus arm's overwhelming population of shell-type remnants.