High Angular Resolution Determination of Extinction in the Orion Nebula
Abstract
The optical appearance of the Orion Nebula is significantly altered by the presence of interstellar extinction. Since Orion is high above the Galactic plane and is nearby, most of this extinction is due to material immediately in front of the associated star cluster. This extinction fundamentally alters the optical appearance of the Orion Nebula. We have quantitatively determined the extinction correction by comparing the surface brightness of the nebula at a resolution of about 1.7" in the radio continuum and the Hα emission line. The results compare well with new determinations made from Hα and Hβ line ratios. Extinction-corrected optical images are generated and discussed. The most important extinction feature, the dark bay that obscures the east side of the nebula, has a mass of about 3 Msolar and possesses numerous small knots of material in addition to a feature that appears to be a shock. We also find that the thin main emitting layer on the front of the parent Orion molecular cloud is marked by numerous walls and plateaus. Only one such structure had been previously known, the one that produces a bright bar across the southeast portion of the nebula. The sharpest structure is associated with the complex of molecular outflow and infrared sources near the region called Orion-S and is likely to be the result of uncollimated outflow from an imbedded young star. Based in part on observations with the Very Large Array of the National Radio Astronomy Observatory, which is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
- Publication:
-
The Astronomical Journal
- Pub Date:
- July 2000
- DOI:
- 10.1086/301429
- Bibcode:
- 2000AJ....120..382O
- Keywords:
-
- ISM: Dust;
- Extinction;
- ISM: General;
- ISM: individual (Orion Nebula)