SIMBAD references

2005A&A...429..993P - Astronomy and Astrophysics, volume 429, 993-998 (2005/1-3)

High-resolution spectroscopic observations of the D'-type symbiotic stars HD 330036 and AS 201.


Abstract (from CDS):

We present high-resolution spectroscopic analyses of two stars classified as D'-type symbiotic stars, HD 330036 and AS 201. These two stars display both rapid rotation and enhancements of the s-process elements that are synthesized via slow neutron captures during stellar evolution along the asymptotic giant branch (AGB). Both characterisitics of rapid rotation and s-process overabundances have also been discovered recently in another D'-type symbiotic, S190. The stellar parameters derived here for HD 330036 are Teff=6200K and logg=2.4, while AS 201 has Teff=6000K and log g=2.3. Resulting luminosity and distance estimates are 650L and 2.3kpc for HD 330036, and 700L and 4.3kpc for AS 201. Both HD 330036 and AS 201 have evolved away from the main sequence and are approaching the base of the red-giant branch. These stars have near-solar abundances of iron and calcium, but substanial enhancements (by about +0.9dex for HD 330036 and +1.7dex for AS 201) of the s-process element barium. The observed barium overabundances in the current cool-star members of these two binary systems probably resulted from mass-transfer when the current white dwarf was an AGB star. The rapid rotation found in the cool stars may also be due to mass-transfer, with the mass-gaining stars being spun up with the transfer of angular momentum from the AGB winds. As only a few (six) D'-type symbiotics are known, the fact that the 3 studied to date at high-spectral resolution all display rapid rotation and s-process elemental overabundances may indicate that these two traits are signatures of these rare binary systems.

Abstract Copyright:

Journal keyword(s): stars: binaries: symbiotic - stars: abundances

Simbad objects: 10

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