NOAO > Observing Info > Approved Programs > 2010B-0335
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NOAO > Observing Info > Approved Programs > 2010B-0335 |
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PI: Robert A. Fesen, Dartmouth College, Robert.A.Fesen@dartmouth.edu
Address: Physics Department, 6127 Wilder Laboratory, Hanover, NH 03755, USA
CoI: Dan Milisavljevic, Dartmouth College
Title: Spectra of Cas A's Highest Velocity Ejecta
Abstract:
The young age and close distance of the Galactic supernova remnant
Cassiopeia A (Cas A) make it perhaps our best case study and clearest
look at the explosion dynamics of a core-collapse supernova (CCSN).
Interestingly, Cas A exhibits two nearly opposing streams of high
velocity ejecta or `jets' in its NE and SW regions racing outward at
speeds more than twice that of the main shell. The nature of these
jets, however, and their possible association with an aspherical
supernova explosion mechanism is controversial.
A handful of existing low-resolution spectra of outer knots in the
NE jet display chemical abundances hinting at an origin from the S-Si-Ca-
Ar rich layer deep inside the progenitor. If these abundances could be
firmly established in both the NE and SW jets, it would be very strong
evidence in support of a highly asymmetrical explosion engine for Cas
A's progenitor and, in turn, for CCSNe in general.
We request KPNO 4m telescope + MARS time to obtain high quality
multi-object spectroscopy of Cas A's highest velocity ejecta to measure
their nitrogen, sulfur, oxygen, calcium, and argon abundances. These
spectra will be analyzed with the metal-rich shock models of J. Raymond
and then compared to current sets of CCSN models paying particular
attention to knot composition vs. ejection velocity and ejecta mixing.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2010B-0335 |
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