Preprint article · Journal article
The Distribution of Radioactive 44ti In Cassiopeia A
California Institute of Technology1
Astrophysics and Atmospheric Physics, National Space Institute, Technical University of Denmark2
Lawrence Livermore National Laboratory3
ASI Science Data Center4
Columbia University5
Hiroshima University6
SLAC National Accelerator Laboratory7
Ohio State University8
National Institute for Astrophysics9
Johns Hopkins University10
NASA Goddard Space Flight Center11
Los Alamos National Laboratory12
University of California at Berkeley13
West Virginia Wesleyan College14
Naval Research Laboratory15
University of North Carolina at Chapel Hill16
Durham University17
Université Fédérale Toulouse Midi-Pyrénées18
National Space Institute, Technical University of Denmark19
...and 9 moreThe distribution of elements produced in the innermost layers of a supernova explosion is a key diagnostic for studying the collapse of massive stars. Here we present the results of a 2.4 Ms NuSTAR observing campaign aimed at studying the supernova remnant Cassiopeia A (Cas A). We perform spatially resolved spectroscopic analyses of the 44Ti ejecta, which we use to determine the Doppler shift and thus the three-dimensional (3D) velocities of the 44Ti ejecta.
We find an initial 44Ti mass of (1.54 ± 0.21) × 10−4 M ⊙, which has a present-day average momentum direction of 340° ± 15° projected onto the plane of the sky (measured clockwise from celestial north) and is tilted by 58° ± 20° into the plane of the sky away from the observer, roughly opposite to the inferred direction of motion of the central compact object.
We find some 44Ti ejecta that are clearly interior to the reve0rse shock and some that are clearly exterior to it. Where we observe 44Ti ejecta exterior to the reverse shock we also see shock-heated iron; however, there are regions where we see iron but do not observe 44Ti. This suggests that the local conditions of the supernova shock during explosive nucleosynthesis varied enough to suppress the production of 44Ti by at least a factor of two in some regions, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium.
Language: | English |
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Publisher: | American Astronomical Society |
Year: | 2016 |
Pages: | 19 |
ISSN: | 15384357 , 0004637x , 15384365 and 00670049 |
Types: | Preprint article and Journal article |
DOI: | 10.3847/1538-4357/834/1/19 |
ORCIDs: | Christensen, Finn Erland , Hornstrup, Allan , Westergaard, Niels Jørgen Stenfeldt , 0000-0002-1984-2932 , 0000-0003-2624-0056 , 0000-0003-2992-8024 , 0000-0002-3362-7040 , 0000-0002-5365-5444 , 0000-0002-5896-6313 , 0000-0002-0393-9190 , 0000-0003-1252-4891 , 0000-0002-8074-4186 , 0000-0002-2734-7835 , 0000-0003-1703-8796 , 0000-0003-2686-9241 and 0000-0001-8952-676X |