Barium-rich G stars in the nuclei of the planetary nebulae Abell 35 and LoTr5.
Abstract
A spectroscopic analysis of the G-star located at the centre of Abell 35 leads to a surface gravity logg=3.7+/-0.5 and an effective temperature T_eff_=5300+/-200K, which are typical of a G8IV spectral type. We estimate a projected rotational velocity of 55+/-10km/s and deduce a radius 1.5<=R_G_<=3.5Rsun_ in agreement with the subgiant luminosity class: the star is rapidly rotating, near the break-up as for LoTr5 (Jasniewicz et al. 1996A&A...307..200J). For both late-type central stars of Abell 35 and LoTr5, we show a photospheric enhancement of the barium element which can be understood as caused by the transfer of s-process-overabundant material from the former AGB star which is now the hot star of the binary. These G-stars could be pre-barium stars in detached binary systems.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 1997
- Bibcode:
- 1997A&A...320..913T
- Keywords:
-
- PLANETARY NEBULAE: INDIVIDUAL: ABELL 35;
- PN LOTR 5;
- STARS: BINARIES;
- STARS: ABUNDANCES;
- STARS: CHEMICALLY PECULIAR