The Origem Loop
Abstract
Context. The Origem Loop in the Galactic anticentre was discovered in 1970s. It has been suggested that it is a large supernova remnant. One later argument is that it is a chance superposition of unrelated radio sources.
Aims: We attempt to understand the properties of the Origem Loop.
Methods: Available multi-frequency radio data were used to determine the radio spectra of different parts of the Origem Loop and the polarization properties of the loop.
Results: Newly available sensitive observations show that the Origem Loop is a loop of more than 6° 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 λ6 cm, revealing tangential magnetic fields. The arc has a brightness-temperature spectral index of β = -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.
Conclusions: 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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 2013
- DOI:
- 10.1051/0004-6361/201219805
- arXiv:
- arXiv:1212.1523
- Bibcode:
- 2013A&A...551A..16G
- Keywords:
-
- ISM: supernova remnants;
- radio continuum: ISM;
- ISM: individual objects: Origem Loop;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 8 pages, 7 figures, accepted by A&