Spatial Structure of the Interstellar Gas toward the Globular Cluster M22
Abstract
High-resolution spectra of Na I interstellar lines are presented for 14 stars in the globular cluster M22. The interstellar gas foreground to the cluster at distance about 2.6 kpc occurs essentially in two velocity ranges. There is a low-velocity component which is quite uniform across the cluster. This gas feature is likely to be a part of the extensive and nearby H I cloud first mapped in the radio region. There is also gas at higher velocities detected between +25 and 60 km/s which is observed with both a single- and a multi-component structure. Significant profile variations for this gas occur on a scale less than 1 arcmin. The location of this gas is not known but it may be associated with the Sagittarius arm. Spectra of the K I interstellar line for a nearby star roughly 1.3 deg from the cluster and for two cluster members provide useful estimates for the column densities of the gas components.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1991
- DOI:
- 10.1086/185996
- Bibcode:
- 1991ApJ...371L..37B
- Keywords:
-
- Globular Clusters;
- Interstellar Gas;
- Stellar Spectra;
- Flow Velocity;
- Gas Flow;
- High Resolution;
- Line Spectra;
- Astrophysics;
- CLUSTERS: GLOBULAR;
- INTERSTELLAR: MATTER;
- LINE PROFILES