Interstellar absorption-line evidence for high-velocity expanding structures in the Carina Nebula foreground

The extreme, high-velocity interstellar absorption-line profiles toward η Carinae and 16 neighboring stars in Trumpler 16 are examined, including several new sight lines observed in the ultraviolet with the Hubble Space Telescope or in the optical from the Magellan and European Southern Observatories. No two sight lines are identical, but many velocity components are in common. When the velocity scale is shifted to a standard of rest defined by the Carina Nebula emission lines, the symmetries between negative and positive velocities are striking; at least 15 distinct "shells" can be recognized. This circumstance suggests that the complex expanding structures are predominantly in front of the ionizing cluster. There may be a relationship to indications of a supernova remnant in this direction, including a recent Chandra X-Ray Observatory image. Interpretations in terms of high-energy phenomena generated by ongoing star formation possibly on the near side of the giant H II region are also discussed.