Spectroscopic Study of IRAS 19285+0517 (PDS 100): A Rapidly Rotating Li-Rich K Giant
Abstract
We report on photometry and high-resolution spectroscopy for IRAS 19285+0517. The spectral energy distribution based on visible and near-infrared photometry and far-infrared fluxes shows that the star is surrounded by dust at a temperature of Td~250 K. Spectral line analysis shows that the star is a K giant with a projected rotational velocity of vsini=9+/-2 km s-1. We determined the atmospheric parameters: Teff=4500 K, logg=2.5, ξt=1.5 km s-1, and [Fe/H]=0.14 dex. The LTE abundance analysis shows that the star is Li-rich [logɛ(Li)=2.5+/-0.15], but with essentially normal C, N, O, and metal abundances. Spectral synthesis of molecular CN lines yields the carbon isotopic ratio 12C/13C=9+/-3, a signature of post-main-sequence evolution and dredge-up on the red giant branch (RGB). Analysis of the Li resonance line at 6707 Å for different 6Li/7Li ratios shows that the Li profile can be best fitted with a predicted profile for pure 7Li. Far-infrared excess, high Li abundance, and rapid rotation suggest that a planet has been swallowed or, perhaps, that an instability in the RGB outer layers triggered a sudden enrichment of Li and caused mass loss.
- Publication:
-
The Astronomical Journal
- Pub Date:
- April 2002
- DOI:
- 10.1086/339310
- arXiv:
- arXiv:astro-ph/0112259
- Bibcode:
- 2002AJ....123.1993R
- Keywords:
-
- Stars: Abundances;
- stars: individual (IRAS 19285+0517);
- Astrophysics
- E-Print:
- To appear in AJ