The Reddening Toward Cassiopeia A's Supernova: Constraining the 56Ni Yield
Abstract
We present new reddening measurements toward the young supernova remnant Cassiopeia A using two techniques not previously applied to this object. Our observations of the near-infrared [Fe II] 1.257 μm and 1.644 μm lines show the extinction to be highly variable across the remnant, increasing toward the west and the south, consistent with previous radio and X-ray observations. While the absolute value of AV as determined by the [Fe II] lines is uncertain due to conflicting calculations and observations of their intrinsic flux ratio, parts of the remnant without previous optical measurements show comparatively higher reddening. We find AV = 6.2 ± 0.6 from the broadband shape of the infrared synchrotron emission of a knot within 13'' of the expansion center. Given this reddening, the apparent faintness of the nascent supernova, and iron mass constraints from X-ray observations, we estimate an ejected mass of 56Ni of 0.058-0.16 M sun. Taken with γ-ray observations of the 44Ti decay chain, this nickel mass is broadly consistent with the solar 44Ca/56Fe ratio.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2009
- DOI:
- 10.1088/0004-637X/697/1/29
- arXiv:
- arXiv:0902.4029
- Bibcode:
- 2009ApJ...697...29E
- Keywords:
-
- dust;
- extinction;
- nuclear reactions;
- nucleosynthesis;
- abundances;
- supernova remnants;
- supernovae: individual: SN1680;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 8 pages, 6 figures, accepted for publication in The Astrophysical Journal