Interstellar Ti II Observations Toward Southern Galactic Halo Stars
Session 54 -- MW, Galactic Structure
Oral presentation, Wednesday, 10:30-12:00, Dwinelle 155 Room

## [54.07] Interstellar Ti II Observations Toward Southern Galactic Halo Stars

C. E. Albert (USNA), B. Y. Welsh (NASA Headquarters), L. Danly (ST ScI)

We present observations of interstellar absorption in the galactic halo by the $\lambda$3384 line of Ti II toward distant southern OB stars. The data were obtained with the CTIO 1.5 m telescope and increase significantly the number of Ti II detections toward halo stars located more than one kiloparsec from the galactic plane. Since singly ionized Titanium is the dominant ionization stage in H I regions and since the $\lambda$3384 line is generally unsaturated, this species provides a unique opportunity to trace the extent and depletion of neutral gas in the halo. Preliminary results indicate that the projected column density, N(Ti II)sin(b), continues to increase out to the most distant star in our sample, at z=8.7: kpc. Observations toward extragalactic sources are needed to determine the scale height of neutral halo gas.