Limits on Turbulent H I Fluctuations toward PSR B0329+54 on Scales between 0.0025 and 12.5 AU

We have measured the H I absorption toward pulsar B0329+54 using the Green Bank Telescope during 18 epochs between 2002 June 30 and 2003 October 10. Three observing epochs consisted of a continuous period of 20 hr each, while 15 epochs were 1-2 hr each. We calculate the structure function of H I abs...

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Bibliographic Details
Published in:The Astrophysical journal 2005-09, Vol.631 (1), p.376-380
Main Authors: Minter, Anthony H, Balser, Dana S, Kartaltepe, Jeyhan S
Format: Article
Language:English
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Summary:We have measured the H I absorption toward pulsar B0329+54 using the Green Bank Telescope during 18 epochs between 2002 June 30 and 2003 October 10. Three observing epochs consisted of a continuous period of 20 hr each, while 15 epochs were 1-2 hr each. We calculate the structure function of H I absorption variations toward the pulsar on timescales of 10 minutes to 16 months, which using the proper motion of 95 km s super(-1) and the parallactic distance of 1.03 kpc measured toward B0329+54 (Brisken et al.), corresponds to angular scales of 0.37 kas to 23.8 mas and samples structures between 0.0025 and 12.5 AU, assuming H I gas halfway to the pulsar and ignoring scintillation effects. We find no evidence for any turbulent H I absorption fluctuations toward B0329+54, with the following upper limits on tau for various absorption features: 0.026 at -31, -21, -18, and +4 km s super(-1); 0.12 at -11 km s super(-1); and 0.055 at -1 km s super(-1).
ISSN:0004-637X
1538-4357
DOI:10.1086/432367