DETECTION OF A LOCAL HIGH-VELOCITY ABSORPTION-LINE SYSTEM TOWARD HD-93721

High-resolution spectroscopic observations of the star HD 93721, which is located near the IRAS cloud DBB 414, reveal the presence of at least 10 components of Ca II absorption, ranging in velocity from v(lsr) = -65 km s-1 to v(lsr) = +75 km s-1, for a total velocity range of 140 km s-1. Interstellar Ca II components with N(Ca II) ranging from 6 x 10(10) to 9.0 x 10(11) cm-2 are observed, while spectroscopic observations of Na I absorption show a total of five interstellar components ranging in velocity from -58 to -13 km s-1, with a total N(Na I) = 7.0 x 10(11) cm-2. Low-resolution spectra for the star HD 93721 provide a spectral type of B9.5 III, which when combined with new photometry places the star at a distance of d = 410 +/- 50 pc. Additional observations of the star HD 94724, a B9.0 III star at d = 210 pc, reveals only very weak interstellar absorption lines, placing the main absorbing cloud at a distance of 200 pc < d < 450 pc. An examination of Ca I/Ca II ratios toward HD 93721 reveals that the Ca in the absorption system is almost completely ionized, with values of n(e) < 2.5(T(cloud)/70 K)0.5 cm-3. N(Ca II)/N(Na I) values range from 2.2 to greater than 20.0, indicating the presence of a wide range of disruption in the sightline. The observed column density N(H I) toward the region is 2.4 x 10(20) cm-2, and using the ratio N(Na I)/N(H I), we derive a value of n(H) = 4.1 +/- 0.5 cm-3. Spectroscopic observations at the wavelengths of CH+, and CH were taken for both stars, resulting in upper limits of N(CH) < 1.2 x 10(12) cm-2 , and N(CH+) < 1.7 x 10(12) cm-2. Examination of both optical and infrared sky-survey plates reveals the location of the cloud at the edge of an extended filament which may be associated with the interaction of a high-velocity cloud with the local interstellar medium in the vicinity of the Gum Nebula.