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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 198543.0, MPI für Astronomie / Publikationen_mpia
Knots in planetary nebulae
Authors:O'dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; Burkert, A.
Date of Publication (YYYY-MM-DD):2003
Title of Journal:Revista Mexicana DE Astronomia y Astrofisica. Conference Series
Journal Abbrev.:Revista Mexicana de Astronomia y Astrofisica. Conference Series
Volume:15
Start Page:29
End Page:33
Review Status:not specified
Audience:Not Specified
Abstract / Description:We have studied the closest bright planetary
nebulae with the Hubble Space Telescope's WFPC2
in order to characterize the dense knots already
known to exist in NGC 7293. We find knots in all
of the objects, arguing that knots are common,
simply not always observed because of distance.
The knots appear to form early in the life cycle
of the nebula, probably being formed by an
instability mechanism operating at the nebula's
ionization front. As the front passes through the
knots they are exposed to the photoionizing
radiation field of the central star, causing them
to be modified in their appearance. This would
then explain as evolution the difference of
appearance like the lacy filaments seen only in
extinction in IC 4406 on the one extreme and the
highly symmetric ``cometary" knots seen in NGC
7293. The intermediate form knots seen in NGC
2392, NGC 6720, and NGC 6853 would then represent
intermediate phases of this evolution.
Free Keywords:ISM: Planetary Nebulae
External Publication Status:published
Document Type:Article
Version Comment:Automatic journal name synchronization
Communicated by:N. N.
Affiliations:MPI für Astronomie
External Affiliations:Tennessee, USA.), AB(University of Washington,
Seattle, Washington, USA.), AC(US Naval
Observatory, Washing, DC, USA), AD(Instituto de
Astronom iacute;a, UNAM, Morelia,
M eacute;xico), AE(Max Planck Inst. for
Astronomy, Heidelberg, Germany)
Identifiers:URL:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi... [ID No:1]
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