Elemental abundance determination of 17 HgMn stars

SAFFE CARLOS; NUÑEZ NATALIA; GONZÁLEZ JORGE FEDERICO; GONZALEZ ELIZABETH JOHANA

Salta

Congreso; Reunión Anual de la Asociación Argentina de Astronomía; 2010

Instituto de Astronomía Teórica y Experimental

We aim to derive abundances for a sample of 17 HgMn field stars, to de-termine a possible dependence with the rotational velocity and to searchcandidate to variable HgMn stars within the sample. Effective temperature and gravity were estimated by Strömgren photometry, and then refined by fitting a synthetic spectra to the Hbeta and Hγ regions. We derived the abundances using equivalent width measurements together with ATLAS9 model atmospheres and the WIDTH9 program. We derive for the first time the metallic abundances for 11 HgMn stars for 23 different species. For the HgMn group, there is an agreement between fundamental parameters derived using the Hbeta and Hγ regions separately. Our preliminar result suggest that the variability could be common between HgMn stars, adopting 30% as a lower limit. A comparison of Teff vs Mn II abundances for the sample of HgMn stars shows that the envelope of the values seems to increase with temperature, as resulted in previous works. The LTE abundances of C II, S II and Xe II probably decrease with T eff , however the values may change in NLTE and should be taken with caution. The observed range in vsini cover 14-35 km/s, and we completed with literature stars up to 85 km/s. In this work we report a poor tendence in which the overabundances of Mn II and Hg II seem to diminish with vsini. We expect to increase the number of HgMn stars studied to verify this trend.