Oxygen and nitrogen abundances in cold H II regions from SLOAN Digital Sky Survey

Zinchenko, IA, Pilyugin, LS
Kinemat. fiz. nebesnyh tel (Online) 2011, 27(6):3-17
Start Page: Extragalactic Astronomy
Language: Russian
Abstract: 

The oxygen and nitrogen abundances for a sample of 113 607 cold objects from the Sloan Digital Sky Survey (SDSS) spectra are derived. The values of oxygen abundances 12+lg(O/H) are obtained using three parametric N calibrations one of which is developed in this work. The values of ntirogen abundances 12+lg(N/H) are found with two N calibrations. The values of oxygen abundances which are derived using three parametric N calibrations are consistent within 0.05 dex for the vast majority of the objects. It is not improbable that there are systematic differences between the values of oxygen abundances which do not exceed 0.05 dex. The differences between the values of nitrogen abundances which are obtained using the ON and NS calibrations reach 0.1 dex. It is shown that the vast majority of cold SDSS objects are in the same area of the diagram O/H — N/O that cold HII regions of nearby galaxies, oxygen and nitrogen abundances for which are derived through the Te-method. This is indirect evidence that the values of oxygen and nitrogen abundances which are found with parametric N calibrations are reliable.

Keywords: cold H II region, nitrogen abundance, oxygen abundance