The Distances of Planetary Nebulae: A Scale Based upon Nearby Sources
2002; Institute of Physics; Volume: 139; Issue: 1 Linguagem: Inglês
10.1086/338028
ISSN1538-4365
Autores Tópico(s)History and Developments in Astronomy
ResumoThe statistical distances of planetary nebulae (PNe) are known to be notoriously uncertain, differing from each by factors approaching ∼2, and also from more reliable distances based upon trigonometric and spectroscopic parallaxes, expansion distances, and so forth. We point out that many of these problems arise from the use of inappropriate relations between surface brightness and nebular radius; of incomplete samples of standard sources; and the use of indirect (and/or inaccurate) methods for the evaluation of distances. Many of these problems can be side-stepped, however, where the standard sources are confined to nearby nebulae; planetaries whose distances are less than ∼0.7 kpc or so.
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