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

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 to a spatial extent of about 4 pc at a distance of 4.0 kpc. It displays a radio spectral index of alpha approximate to -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 center of a small spherical Hi bubble, which is expanding at a velocity of 6 km s(-1) at a systemic velocity of upsilon(LSR) = -53 km s(-1). The bubble could be the result of the progenitor star's mass loss or the shell-type supernova remnant (SNR) created by the same supernova explosion in a highly advanced stage. The systemic LSR velocity of the bubble shares the velocity of Hi associated with the Cygnus spiral arm, which is seen across the second and third 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). 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.