4He Abundances: Optical vs Radio Dana S' Balser

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4He Abundances Optical vs RadioDana S. Balser
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Collaborators
Tom Bania
Bob Rood
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Radio Recombination Lines

• Sensitivity
• Spectral Baselines
• Departures from LTE
• Ionization Structure
• Density Structure

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4He/H RRLs with the 140 Foot Telescope
Peimbert et al. (1992)
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Green Bank Telescope Observations
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Planetary Nebulae
NGC 3242
NGC 6543
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Balick et al.
NGC 7009
NGC 6826
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GBT PNe Radio Recombination Lines
NGC 3242
NGC 6543
NGC 7009
NGC 6826
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HII Regions M17
Radio Continuum (9GHz)
Optical (Halpha)
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60
Maddalena et al.
MacQuarrie
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HII Regions S206
Optical (Halpha)
Radio Continuum (9 GHz)
Pismis Mampaso (1991)
Balser (2006)
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GBT HII Region Radio Recombination Lines
M17N
S206
S206
M17N
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4He/H Planetary Nebulae
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4He/H HII Regions
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Summary

• 4He/H differences as large as 20 between Optical
  and Radio
• Galactic dY/dZ 1 (M17, S206)

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Future Work

• Explore 4He/H with n
• Models of PNe and HII Regions
• EVLA

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Extra Slides
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Expanded View M17N
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Expanded View S206
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M17S
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Expanded View M17S