The Chemical Abundances of Tycho G in Supernova Remnant 1572

J. I. González Hernández (1, 2) , Pilar Ruiz-Lapuente (3) , Alexei V. Filippenko (4) , Ryan J. Foley (4) , Avishay Gal-Yam (5) , Joshua D. Simon (5)

1 GEPI - Galaxies, Etoiles, Physique, Instrumentation
2 CIFIST - Cosmological Impact of the First Stars
3 Departament d'Astronomia, Universitat de Barcelona
4 Department of Astronomy, University of California
5 CALTECH - California Institute of Technology, Department of Astronomy

We present an analysis of the chemical abundances of the star Tycho G in the direction of the remnant of supernova (SN) 1572, based on Keck high-resolution optical spectra. The stellar parameters of this star are found to be those of a G-type subgiant with T _eff = 5900 ± 100 K, log(g/cms²) = 3.85 ± 0.30 dex, and [Fe/H] = -0.05 ± 0.09. This determination agrees with the stellar parameters derived for the star in a previous survey for the possible companion star of SN 1572 (Ruiz-Lapuente et al.). The chemical abundances follow the Galactic trends, except for Ni, which is overabundant relative to Fe, [Ni/Fe] = 0.16 ± 0.04. Co is slightly overabundant (at a low significance level). These enhancements in Fe-peak elements could have originated from pollution by the SN ejecta. We find a surprisingly high Li abundance for a star that has evolved away from the main sequence. We discuss these findings in the context of companion stars of SNe.

Domaines: Astrophysique [astro-ph]

J. I. González Hernández, Pilar Ruiz-Lapuente, Alexei V. Filippenko, Ryan J. Foley, Avishay Gal-Yam, et al.. The Chemical Abundances of Tycho G in Supernova Remnant 1572. The Astrophysical Journal, 2009, 691, pp.1-15. ⟨10.1088/0004-637X/691/1/1⟩. ⟨hal-03743002⟩