CRL 2688 and CRL 618: proto-planetary nebulae
2.6-mm CO J + 1 to 0 emission has been detected from the peculiar infrared objects CRL 2688 (the Egg Nebula) and CRL 618. The observed parabolic line-shape can be interpreted as optically thick emission from a uniformly expanding molecular envelope with a size smaller than the telescope beam. The line-width indicates an expansion velocity on the order of 20 km/s. Other molecular lines similar to those observed in the envelope of the carbon star IRC+10216 are also observed in CRL 2688, even though the central star in CRL 2688 has a relatively early spectral type (F5Ia). In CRL 618, the existence of an expanding molecular envelope around a central star with spectral type B0 implies that the central star has evolved within a very short time (<10,000 years) from a cool, perhaps carbon-rich, star. The presence of mass-loss and the rapid evolution of the central stars suggest that CRL 2688 and CRL 618 may be proto-planetary nebulae. (GRA)
- Research Organization:
- Owens Valley Radio Observatory, Pasadena, Calif. (USA)
- OSTI ID:
- 7342668
- Report Number(s):
- AD-A-020805
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMISTRY
COSMOCHEMISTRY
EMISSION SPECTRA
INFRARED SPECTRA
NEBULAE
OXIDES
OXYGEN COMPOUNDS
PLANETARY NEBULAE
SPECTRA
STAR EVOLUTION