| Issue |
A&A
Volume 387, Number 1, May III 2002
|
|
|---|---|---|
| Page(s) | L1 - L5 | |
| Section | Letters | |
| DOI | https://doi.org/10.1051/0004-6361:20020330 | |
| Published online | 15 May 2002 | |
Letter to the Editor
Diffuse X-ray emission from the planetary nebula NGC 7009*
Astronomy Department, University of Illinois, 1002 W. Green Street, Urbana, IL 61801, USA
Corresponding author: M. A. Guerrero, mar@astro.uiuc.edu
Received:
7
February
2002
Accepted:
1
March
2002
XMM-Newton EPIC observations of the planetary nebula (PN)
NGC 7009, the Saturn Nebula, have detected extended X-ray emission
in its central cavity.
The diffuse X-ray emission must originate in the shocked fast
stellar wind.
The spectra show that the temperature of the hot gas is
K.
The rms density derived from the volume emission measure is a few tens
H-atom cm-3.
The hot gas does not appear over-pressurized with respect to the
nebular shell.
NGC 7009 represents an evolutionary stage at which the
influence of the hot gas in the PN interior starts to decline
due to the diminishing strength of the fast stellar wind and the
expansion of the central cavity.
Key words: ISM: planetary nebulae: general / ISM: planetary nebulae: individual: NGC 7009 / stars: winds, outflows / X-rays: ISM
© ESO, 2002
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