Астрофизический семинар ИНАСАН № 202 (2 сентября 2010 г., 11:00)

Опубликовано: 02/09/2010

Докладчик: Jianrong Shi (National Astronomical Observatories, Chinese Academy of Sciences, Beijing)

Название доклада: “Si abundances in nearby metal-poor stars”

Краткое содержание доклада:
The statistical equilibrium of neutral and ionized silicon in the atmospheres of nearby metal-poor stars is discussed. Non-local thermodynamic equilibrium (NLTE) effects are investigated and the silicon abundances are determined. It is found that NLTE effects for two strong Si I lines are important for metal-poor stars, in particular for warm metal-poor stars, the NLTE abundance correction reaches ~0.2 dex relative to standard LTE calculations, while NLTE effects for Si II optical lines are important for warm metal-rich stars. They depend on the effective temperatures. Our results show that the Si abundances of thin and thick disk stars show distinct trends, such as in the case of the Mg. [Si/Fe] gradually increases with a decrease in [Fe/H] for thin disk stars, it is around at [Si/Fe] ~ +0.25 dex for thick disk stars; while halo stars show slightly larger scatter around the value of [Si/Fe] ~ +0.30 dex.