A 3D kinematic study of the northern ejecta `jet' of the Crab nebula
Abstract
We present moderate resolution [O III] λλ4959, 5007 line emission spectra of the Crab nebula's northern ejecta jet. These data along with an [O III] image of the Crab nebula were used to build three-dimensional kinematic maps of the jet and adjacent remnant nebulosity to better understand the jet's properties and thus its likely origin. We find the jet's systemic velocity to be +170 ± 15 km s-1 with radial velocities ranging from -190 to +480 km s-1. Our data indicate that the jet consists of thin filamentary walls (Vexp ≃ 40-75 km s-1), is virtually hollow in [O III] emission, and elliptical and funnel-like in shape rather than a straight cylindrical tube as previously thought. Examination of the Crab's 3D filamentary structure along the jet's base reveals a large and nearly emission-free opening in the remnant's thick outer ejecta shell. The jet's blueshifted and redshifted sides are surprisingly well defined and, like the jet's sharp western limb, appear radially aligned with the remnant's centre of expansion. These alignments, along with the opening in the nebula at the jet's base and proper motions indicating an expansion age in line with the 1054 supernova event, suggest a direct connection between the jet's formation and the Crab's radial expansion. While our analysis supports the scenario that the jet may simply represent the highest velocity material of the remnant's N-S bipolar expansion, the nature of this expansion asymmetry remains unclear.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2015
- DOI:
- 10.1093/mnras/stu2641
- arXiv:
- arXiv:1412.3122
- Bibcode:
- 2015MNRAS.447.2540B
- Keywords:
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- supernova remnant;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 11 pages, 8 figures, 2 tables