SBS 0335-052E W: deep VLT-FORS UVES spectroscopy of the pair of the lowest-metallicity blue compact dwarf galaxies - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




SBS 0335-052E W: deep VLT-FORS UVES spectroscopy of the pair of the lowest-metallicity blue compact dwarf galaxies - Astrophysics > Cosmology and Nongalactic Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: abridged We present deep archival VLT-FORS1+UVES spectroscopic observationsof the system of two blue compact dwarf BCD galaxies SBS 0335-052E and SBS0335-052W. Our aim is to derive element abundances in different HII regions ofthis unique system of galaxies and to study spatial abundance variations. Wedetermine abundances of helium, nitrogen, oxygen, neon, sulfur, chlorine, argonand iron. The oxygen abundance in the brighter eastern galaxy varies in therange 7.11 to 7.32 in different HII regions supporting previous findings andsuggesting the presence of oxygen abundance variations on spatial scales of~1-2 kpc. The oxygen abundance in the brightest region No.1 of SBS 0335-052W is7.22+-0.07, consistent with previous determinations.Three other HII regionsare much more metal-poor with an unprecedently low oxygen abundance of12+logO-H=7.01+-0.07 region No.2, 6.98+-0.06 region No.3, and 6.86+-0.14region No.4. These are the lowest oxygen abundances ever derived inemission-line galaxies. Helium abundances derived for the brightest HII regionsof both galaxies are mutually consistent. We derive weighted mean He massfractions of 0.2485+-0.0012 and 0.2514+-0.0012 for two different sets of HeIemissivities. The N-O abundance ratio in both galaxies is slightly higher thanthat derived for other BCDs with 12+logO-H<7.6. This implies that the N-O inextremely metal-deficient galaxies could increase with decreasing metallicity.



Autor: Y.I. Izotov 1 and 2, N.G. Guseva 1 and 2, K.J. Fricke 3 and 2, P. Papaderos 4 and 5 1 Main Astronomical Observatory, Kyiv, Ukrain

Fuente: https://arxiv.org/







Documentos relacionados