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Core-halo structures in the 12CO emission of CIT 6, AFGL 618 and IRAS 21282+5050

Published online by Cambridge University Press:  25 May 2016

M. Meixner
Affiliation:
1University of Illinois, Urbana-Champaign
M.T. Campbell
Affiliation:
1University of Illinois, Urbana-Champaign
W. J. Welch
Affiliation:
2University of California, Berkeley
L. Likkel
Affiliation:
3University of Wisconsin, Eau Claire
M. Tafalla
Affiliation:
4Harvard-Smithsonian C.f.A

Extract

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We present full synthesis 12CO J= 1–0 line emission images of three carbon rich evolved stars: CIT 6, AFGL 618 and IRAS 21282+5050. Each of these objects represents a different stage of evolution: CIT 6 is a carbon star still on the AGB, AFGL 618 is a transition object, and IRAS 21282+5050 is a young planetary nebula. Common to all three sources, we find what appears to be two mass loss components: a bright “core” located at the center of the source and a fainter “halo” surrounding the core (see Table below for observed characteristics). We speculate that the bright core was created by a more recent and higher mass loss rate wind than the fainter surrounding halo. However, concrete support for this idea awaits radiative transfer modelling of the 12CO that we are currently pursuing. Our full synthesis data are combined from millimeter interferometry using the Berkeley–Illinois–Maryland millimeter array (BIMA) and single dish maps using the NRAO 12m. We find that full-synthesis imaging, which combines the sensitivity of single dish and the spatial resolution of interferometry, is the only means to reveal such core-halo structures.

Type
V. From AGB to Planetary Nebulae
Copyright
Copyright © Kluwer 1997