Green Bank Telescope Observations of 3He+: HII Regions

Understand

During the era of primordial nucleosynthesis the light elements 2H, 3He, 4He, and 7Li were produced in significant amounts and these abundances have since been modified primarily by stars.

• Observations of 3He+ in HII regions located throughout the Milky Way disk reveal very little variation in the 3He/H abundance ratio---the "3He Plateau"---indicating that the net effect of 3He production in stars is negligible.
• This is in contrast to much higher 3He/H abundance ratios found in some planetary nebulae.
• This discrepancy is known as the "3He Problem".