We used the VLA to search for ^ { 3 } { He } ^ { + } emission from two Galactic planetary nebulae ( PNe ) : NGC 6572 and J 320 .
Standard stellar models predict that the ^ { 3 } { He } / { H } abundance ratios for PNe should be 1–2 orders of magnitude higher than the primordial value ( ^ { 3 } { He } / { H } \sim { 10 ^ { -5 } } by number ) determined from Galactic H \scriptstyle { II } region abundances and confirmed by WMAP cosmic microwave background results .
Chemical evolution models suggest that fewer than 5 % of all PNe enrich the interstellar medium ( ISM ) with ^ { 3 } { He } at the level of standard stellar models .
Our target PNe are therefore anomalous in that they were selected from a sample deliberately biased to contain objects with properties that maximized the likelihood of a ^ { 3 } { He } detection by the VLA .
We have detected the 8.665 { GHz } hyperfine ^ { 3 } { He } ^ { + } transition in J 320 at the 4 \sigma level .
The ^ { 3 } { He } / { H } abundance ratio is { 1.9 \times 10 ^ { -3 } } with roughly a factor of two uncertainty .
For NGC 6572 we find an upper limit of ^ { 3 } { He } / { H } \lesssim { 10 ^ { -3 } } .
This detection of ^ { 3 } { He } in J 320 makes it the second PN known to have an anomalously high ^ { 3 } { He } abundance confirming that at least some low-mass stars produce significant amounts of ^ { 3 } { He } that survives to the PN stage and enriches the ISM .