Interstellar C-2 toward X Persei (HD 24534)

Interstellar C-2 bands D-X (2313 Angstrom) and F-X (1342 Angstrom) in the s pectrum of X Per were detected in the archive echelle spectra acquired by t he Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Tele scope. The population of C-2 rotational levels was determined from the rota tional lines in the D-X band to obtain kinetic temperature T-k = 45 +/- 15 K. The total C-2 column density N(C-2) = (3.4 +/- 0.5) x 10(13) cm(-2) was calculated using the D-X band with f-value of 0.0545. The analysis of F-X b and with an adopted f-value of 0.1 gave different population of rotational levels of C-2. Possible reasons of this discrepancy are discussed. The FWHM of the C-2 line profile was estimated to be Delta V = 2.7 +/- 1.0 km/s.