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Nächste Seite: Misclassified PNe Aufwärts: Elementary Statistics Vorherige Seite: Planetary nebulae in clusters

X-ray sources

Using the data of recent x-ray satellites (EXOSAT, Einstein, ASCA, ROSAT) 16 PNe were identified as X-ray sources. X-ray emissions can in principle appear
1) as point sources originating in the photospheres or possibly in the coronal regions of hot central stars (T $ \geqq$ 100000 K), and
2) as extended (diffuse) sources showing the existence of very hot (T $ \geqq$ 10$ ^{6}$ K) nebular plasma and fast stellar winds.
Both emisssions together are sometimes called ``two-component model''.

The evidence for extended emission is completely unclear and some detections reported earlier may be spurious (see Chu et al., 1993; Chu, Ho, 1955). The aim of the following summary is to motivate further research of the X-ray emissions of PNe which can be very useful for our understanding of the origin of PNe.


List of X-ray sources

REFERENCES:

  1. Conway G.M., Chu Y.-H., 1997, IAU Symp. No.180, 214 (poster).
  2. Kreysing H.C., Diesch C., Zwiegle J. et al., 1992, A&A 264, 623 (IAU Symp. No.155, 197; 1993).
  3. Tarafdar S.P., Apparao K.M.V., 1988, ApJ 327, 342.
  4. de Korte P.A.J., Claas J.J., Jansen F.A., McKechnie S.P., 1984, in X-Ray Astronomy '84 (eds. M. Oda, R. Giacconi), p.35. (see also Ref.3)
  5. Leahy D.A., Zhang C.Y., Kwok S., 1994, ApJ 422, 205.
  6. Arnaud K., Borkowski K.J., Harrington J.P., 1996, ApJ Lett. 462, L75.
  7. Chu Y.-H., Ho Ch.-H., 1995, ApJ Lett. 448, L127.
  8. Leahy D.A., Zhang C.Y., Volk K., Kwok S., 1996, ApJ 466, 352.
  9. Chu Y.-H., Gruendl R.A., Conway G.M., 1998, ApJ 116, 1882.
  10. Chu Y.-H., Kwitter K.B., Kaler J.B., 1993, AJ 106, 650.
  11. Hoare M.G., Barstow M.A., Werner K., Fleming T.A., 1995, MNRAS 273, 812.
  12. Chu Y.-H., Chang T.H., Conway G.M., 1997, ApJ 482, 891.
  13. Leahy D., Kwok S., Yin D., 1998, Bull. AAS 30, 895. (192th Meeting)
  14. Apparao K.M.V., Tarafdar S.P., 1989, ApJ 344, 826.
  15. Apparao K.M.V., Berthiaume G.D., Nousek J.A., 1992, ApJ 397, 534.
  16. Werner K., Motch C., Pakull M., 1993, IAU Symp.155 (eds. R. Weinberger, A. Acker), 496.


next up previous
Nächste Seite: Misclassified PNe Aufwärts: Elementary Statistics Vorherige Seite: Planetary nebulae in clusters
Lubos Kohoutek
2001-04-02