Parsec-scale Variations in the 7Li/6Li Isotope Ratio Toward IC 348 and
  the Per OB 2 Association
  Measurements of the lithium isotopic ratio in the diffuse interstellar medium
from high-resolution spectra of the LiI {\lambda}6708 resonance doublet have
now been reported for a number of lines of sight. The majority of the results
for the 7Li/6Li ratio are similar to the Solar System ratio of 12.2 but the
line of sight toward o Per, a star near the star-forming region IC 348, gave a
ratio of about 2, the expected value for gas exposed to spallation and fusion
reactions driven by cosmic rays. To examine the association of IC 348 with
cosmic rays more closely, we measured the lithium isotopic ratio for lines of
sight to three stars within a few parsecs of o Per. One star, HD 281159, has
7Li/6Li ~ 2 confirming production by cosmic rays. The lithium isotopic ratio
toward o Per and HD 281159 together with published analyses of the chemistry of
interstellar diatomic molecules suggest that the superbubble surrounding IC 348
is the source of the cosmic rays.
