DETECTION OF C-2, CN, AND NAID ABSORPTION IN THE AGB REMNANT OF HD-56126

We present the detection of molecular absorption lines in the optical spectrum of the post-AGE star HD 56126. The C-2 Phillips A(1) Pi(u) - X(1) Sigma(g)(+) (1,0), (2,0), and (3,0); Swan d(3) Pi(g) - a(3) Pi(u) (0,0) and (1,0); and CN Red system A(2) Pi - X(2) Sigma(+) (1,0), (2, 0), (3,0), and (4,0) bands have been identified. From the identificati on of the molecular bands we find an expansion velocity of 8.5 +/- 0.6 km s(-1) independent of excitation condition or molecular specie. On the basis of the expansion velocity, rotational temperatures, and mole cular column densities we argue that the line-forming region is the AG E remnant. This is in agreement with the expansion velocity derived fr om the CO lines. We find column densities of log N-C2 = 15.3 +/- 0.3 c m(-2) and log N-CN = 15.5 +/- 0.3 cm(-2), and rotational temperatures of T-rot = 242 +/- 20 K and T-rot = 24 +/- 5 K respectively for C-2 an d CN. By studying molecular line absorption in optical spectra of post -AGE stars we have found a new tracer of the AGE remnant. From compari son with the results of CO and IR observations it is possible to obtai n information on non-spherical behavior of the AGE remnant. Using diff erent molecules with different excitation conditions it should be poss ible to study the AGE remnant as a function of the distance to the sta r, and thus as a function of the evolutionary status of the star on th e AGE.