Elemental abundance determination of 17 HgMn stars

SAFFE, CARLOS; NUÑEZ, NATALIA; GONZALEZ, FEDERICO; GONZALEZ, ERIC

Salta

Congreso; 53 Reunión de la Asociación Argentina de Astronomía; 2010

Univ. Nac. de Salta conjuntamente con IATE (Cordoba, CONICET)

We aim to derive abundances for a sample of 17 HgMn field stars, to determine a possible dependence with the rotational velocity and to search candidate to variable HgMn stars within the sample. Effective temperature and gravity were estimated by Stromgren photometry, and then refined by fitting a synthetic spectra to the H and H 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 H and H regions separately. Our preliminar result suggest that the variability could be common between HgMn stars, adopting 30% as a lower limit. A comparison of Teffvs 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 Teff, 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.and H 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 H and H regions separately. Our preliminar result suggest that the variability could be common between HgMn stars, adopting 30% as a lower limit. A comparison of Teffvs 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 Teff, 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.