Binary CSPN and PN abundances
Adam Frankowski
IAA ULB, Bruxelles

The evolutionary scheme considered:

star 1 star 2

MS MS

RGB MS

AGB MS	mass loss & transfer,	pollution of star 2 by AGB	processed matter

PN MS	first PN in the system

WD MS

WD RGB (Ba star)

WD E-AGB (Tc-poor S star)

WD TP-AGB	mass loss & transfer,	accretion disc,	bipolar shaping

WD PN	bipolar!

WD WD

Bipolar PNe are often associated with high mass objects because of their metallicity. But there are exceptions (as many as 1/3 of all bipolars!)

On the other hand, it seems that the main requirement for this morphology is a binary companion.

I try to connect these exceptions to a specific binary evolution path:

In binaries it is possible to form a planetary nebula (PN) twice - first, when the initially more massive star departs from its AGB stage and for the second time - when the initially less massive component does so.

If the system was close enough for mass transfer during the first component's AGB, then the elemental abundances of the second PN should bear traces of the mass transfer event.

2005-06-29T13:44:04