Exosat observations of the ring nebula NGC 6888 and HD 192163

A 25-hr exposure of the ring nebula NGC 6888 was obtained with the Exosat X-ray observatory. X-ray emission of the nebula was not found. Taking all instrumental effects and the large nebular area into account, a conservative upper limit of 1 x 10 to the -12th erg/s per sq cm is derived. This is abou...

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Veröffentlicht in:	Astrophysics and space science 1987-07, Vol.135 (1), p.105-109
Hauptverfasser:	KÄHLER, H, ULE, T, WENDKER, H. J
Format:	Artikel
Sprache:	eng
Schlagworte:	Astronomy Earth, ocean, space Exact sciences and technology Quasars. Active or peculiar galaxies, objects, and systems Stellar systems. Galactic and extragalactic objects and systems. The universe
Online-Zugang:	Volltext
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Zusammenfassung:	A 25-hr exposure of the ring nebula NGC 6888 was obtained with the Exosat X-ray observatory. X-ray emission of the nebula was not found. Taking all instrumental effects and the large nebular area into account, a conservative upper limit of 1 x 10 to the -12th erg/s per sq cm is derived. This is about an order of magnitude less than predicted from braking the stellar wind of the central star HD 192163. Two point sources were serendipitously found in the field, HD 192163 and HD 192020. (Author)
ISSN:	0004-640X 1572-946X
DOI:	10.1007/BF00644465