Astronomy and Astrophysics – Astronomy
Scientific paper
Oct 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995apj...452..286s&link_type=abstract
Astrophysical Journal v.452, p.286
Astronomy and Astrophysics
Astronomy
29
Ism: Planetary Nebulae: General, Ism: Structure, Stars: Agb And Post-Agb, Stars: Evolution
Scientific paper
A homogeneous sample of 24 elliptical multiple-shell planetary nebulae (EM PNs) have been studied together with their central stars in order to disclose possible correlations between the stellar and nebular aspects and to find the evolutionary paths yielding to these observed configurations. We propose a finer classification for EM PNs, depending on the appearance of the outer halo, based on detailed Hα surface brightness maps. We define detached-halo (DH), attached-halo (AH), and attached-halo/irregulars (AH/I) PNs. The evolutionary paths examined in comparison to the observations were (1) multiple ejection at the thermal pulsating asymptotic giant branch phase (TP-AGB), including wind and superwind; (2) shell ejection during the postasymptotic giant branch (post-AGB) cooling phase; and (3) asymmetric shell expansion.
Our analysis indicates that
1. DH and AH PNs have different intrinsic nature, they show distinct galactic distributions, and they seem to originate through different evolutionary paths. DH PNs are round, while AH PNs often show marked ellipticity.
2. DH PNs might originate from multiple shell-ejection at the TP-AGB or from a "born again" episode, which is indicated by the spectral type of the central star.
3. Most AH PNs owe their shapes to dynamical processes due to winds interaction, mostly asymmetrical.
4. One AH/I and two AH PNs are probably projected bipolars, as their chemistry suggests.
Pasquali Anna
Stanghellini Letizia
No associations
LandOfFree
Evolutionary Paths in Multiple-Shell Planetary Nebulae does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Evolutionary Paths in Multiple-Shell Planetary Nebulae, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Evolutionary Paths in Multiple-Shell Planetary Nebulae will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1352841