The Origem Loop
  The Origem Loop in the Galactic anticentre was discovered in 1970s and
suggested to be a large supernova remnant. It was argued later to be a chance
superposition of unrelated radio sources. We attempt to understand the
properties of the Origem Loop. Available multi-frequency radio data were used
for the determination of radio spectra of different parts of the Origem Loop
and the polarization properties of the loop. Newly available sensitive
observations show that the Origem Loop is a loop of more than 6 deg in
diameter. It consists of a large non-thermal arc in the north, which we call
the Origem Arc, and several known thermal H II regions in the south. Polarized
radio emission associated with the arc was detected at 6 cm, revealing
tangential magnetic fields. The arc has a brightness temperature spectral index
of \beta = -2.70, indicating its non-thermal nature as a supernova remnant. We
estimate the distance to the Origem Arc to be about 1.7 kpc, similar to those
of some H II regions in the southern part of the loop. The Origem Loop is a
visible loop in the sky, which consists of a supernova remnant arc in the north
and H II regions in the south.
