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 [FeII] 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 [FeII] 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. Taken with γ-ray observations of the 44Ti decay chain, this nickel mass is broadly consistent with the solar 44Ca/56Fe ratio.
Original language | English (US) |
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Pages (from-to) | 29-36 |
Number of pages | 8 |
Journal | Astrophysical Journal |
Volume | 697 |
Issue number | 1 |
DOIs | |
State | Published - 2009 |
Keywords
- Abundances
- Dust
- Extinction
- Nuclear reactions
- Nucleosynthesis
- Supernova remnants
- Supernovae: individual (SN1680)
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science