Issue |
Astron. Astrophys. Suppl. Ser.
Volume 126, Number 3, December II 1997
|
|
---|---|---|
Page(s) | 385 - 391 | |
DOI | https://doi.org/10.1051/aas:1997272 | |
Published online | 15 December 1997 |
Wind variability in central stars of planetary nebulae. II.
1
GNA/CNR, c/o Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy
2
Dipartimento di Astronomia e Scienza dello Spazio, Universitá di Firenze, Largo E. Fermi 5, I-50125 Firenze, Italy
Send offprint request to: M. Perinotto
Received:
14
May
1996
Accepted:
8
April
1997
New high resolution IUE spectra of central stars of the planetary nebulae
(CSPN) NGC 40, NGC 6543, NGC 6826, and BD +30 3639 have been obtained
between August 1994 and September 1995 to explore the variability of their
P Cygni profiles.
The data have been analyzed together with
previous observations of the same stars.
Significant changes in the profiles of several of the
typical wind lines of the N v, O iv, O v, Si
iv, C iv, and N iv ions have been
revealed in all the observed stars.
By combining these results with the ones obtained in a previous
paper of this series (Patriarchi & Perinotto 1995; Paper I),
it is found that half of the fourteen observed CSPN
exhibit changes in the shape of their P
Cygni profiles up to levels of in timescales of years,
analogous to similar timescale variations exhibited by
hot stars of population I. They are: NGC 40, NGC 1535, NGC 2392,
NGC 6543, NGC 6826, IC 4593 and
3639. The ones for which
changes have not been detected are: NGC 246, NGC 6210, NGC 6572,
NGC 7009, IC 418, IC 2149 and Lo 8.
The present paper completes the
survey of this type (at least 2-3 well separated high resolution
good exposures for each star) that could have been done in
central stars of planetary nebulae using the IUE satellite.
In a typical case (NGC 1535) we estimate that the changes
in the physical properties of the wind, resulting from the
observed changes in the P Cygni profiles, amount for
to a factor of
.
Key words: planetary nebulae: general / stars: mass loss
© European Southern Observatory (ESO), 1997