Interaction of hot stars and the interstellar medium. IX. Morphology, excitation and kinematics of SH 2-158 (NGC 7538), a bright high excitation galactic nebula.
Abstract
The presented study covers several properties displayed at optical wavelengths, including morphology, excitation, reddening, electron density, and kinematics of the nebula. The region was selected for detailed study because it is an optical region excited by a relatively hot star (spectral type O 7 or earlier) which is neither a Wolf-Rayet star nor a member of a rich stellar cluster (in contrast for instance with M8, M17, and many others). A description is provided of monochromatic photographs, low-dispersion spectra obtained at a number of positions in the nebula, and data on embedded stars. The velocity field obtained from H-alpha interferograms is considered, taking into account radio recombination or molecular lines. The brightness and electron density distributions, obtained from moderate dispersion spectra are also considered and attention is given to the excitation, reddening, density, and localization in a complex of molecular clouds.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1979
- Bibcode:
- 1979A&A....71..151D
- Keywords:
-
- Astrophysics;
- Hot Stars;
- Hydrogen Clouds;
- Nebulae;
- Visual Observation;
- Astronomical Photography;
- Density Distribution;
- Electron Density (Concentration);
- H Alpha Line;
- H Beta Line;
- Interstellar Extinction;
- Interstellar Gas;
- Interstellar Masers;
- Luminous Intensity;
- Radial Velocity;
- Wolf-Rayet Stars;
- Astrophysics;
- Electron Densities:H II Regions;
- H II Regions:Exciting Stars;
- H II Regions:Infrared Sources;
- H II Regions:Kinematics;
- H II Regions:Photometry;
- H II Regions:Structure