Iron Depletion in the Hot Bubbles in Planetary Nebulae
Abstract
We have searched for the emission from [Fe X] λ6374 and [Fe XIV] λ5303 that is expected from the gas emitting in diffuse X-rays in BD +30°3639, NGC 6543, NGC 7009, and NGC 7027. Neither line was detected in any object. Models that fit the X-ray spectra of these objects indicate that the [Fe X] λ6374 emission should be below our detection thresholds, but the predicted [Fe XIV] λ5303 emission exceeds our observed upper limits (1 σ) by factors of at least 3.5-12. The best explanation for the absence of [Fe XIV] λ5303 is that the X-ray plasma is depleted in iron. In principle, this result provides a clear chemical signature that may be used to determine the origin of the X-ray gas in either the nebular gas or the stellar wind. At present, although various lines of evidence appear to favor a nebular origin, the lack of atmospheric and nebular iron abundances in the objects studied here precludes a definitive conclusion.
Based on observations obtained at the Observatorio Astronómico Nacional in San Pedro Mártir, Baja California, Mexico. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2006
- DOI:
- 10.1086/499218
- arXiv:
- arXiv:astro-ph/0511681
- Bibcode:
- 2006ApJ...639..185G
- Keywords:
-
- ISM: Planetary Nebulae: Individual: Alphanumeric: BD +30°3639;
- ISM: Planetary Nebulae: Individual: NGC Number: NGC 6543;
- ISM: Planetary Nebulae: Individual: NGC Number: NGC 7009;
- ISM: Planetary Nebulae: Individual: NGC Number: NGC 7027;
- Stars: Winds;
- Outflows;
- X-Rays: ISM;
- Astrophysics
- E-Print:
- 23 pages, 4 figures