Microwave investigation of the trifid nebula and its surrounding environment
Journal Article
·
· Astrophys. J., v. 199, no. 3, pp. 647-659
The M20 gaseous nebula and the nearby environment in which it resides have been studied extensively at microwave wavelengths. New maps of thermal bremsstrahlung radiation are used to delineate the full extent of the ionized gas relative to the partially obscuring matter of an adjacent molecular cloud. Extensive observations of the 110$alpha$ recombination-line set are combined with the continuum radio emission to estimate several bulk nebular parameters: n/sube/ approx. =100 cm$sup -3$, EMapprox. =10$sup 4$$.$$sup 7$ pc cm$sup -6$, Mapprox. =210 M/sub sun/, L/subc/approx. =10$sup 48$$.$$sup 8$ photons s$sup -1$, T/sube/ approx. =8150 K, n (He)/n (H) approx. =0.095, and v/subt/approx. =8.5 km s$sup -1$. The distribution of derived neubular properties in many respects shows closer agreement with what is theoretically expected of galactic nebulae than does perhaps any other H ii region investigated to date by radio techniques: normal helium abundance, subsonic turbulence, considerable symmetry about the exciting star, and T/sube/ values that agree well with those found by optical techniques and that suggest a positive thermal gradient with nebular radius.
- Research Organization:
- Center for Astrophysics, Harvard College Observatory, Cambridge, MA
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-33-001650
- OSTI ID:
- 4188765
- Journal Information:
- Astrophys. J., v. 199, no. 3, pp. 647-659, Journal Name: Astrophys. J., v. 199, no. 3, pp. 647-659; ISSN ASJOA
- Country of Publication:
- United States
- Language:
- English
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