Deep VLT spectroscopy of the blue compact dwarf galaxies Tol 1214–277 and Tol 65 ^*,**,***

¹ Main Astronomical Observatory, Ukrainian National Academy of Sciences, 27 Zabolotnoho str., Kyiv 03680, Ukraine
² Universitäts – Sternwarte, Geismarlandstraße 11, 37083 Göttingen, Germany
³ Astronomy Department, University of Virginia, Charlottesville, VA 22903, USA

Corresponding author: Y. I. Izotov, izotov@mao.kiev.ua

Received: 11 December 2003
Accepted: 29 March 2004

Abstract

We present VLT spectroscopic observations with different spectral resolutions and different slit orientations of the two metal-deficient blue compact dwarf (BCD) galaxies Tol 1214–277 and Tol 65. The oxygen abundances in the brightest H ii regions of Tol 1214–277 and Tol 65 are found to be and , or /24. The nitrogen-to-oxygen abundance ratios in the two galaxies are log N/O = – and – and lie in the narrow range found for other most metal-deficient BCDs. The helium mass fraction derived in several H ii regions in both galaxies is consistent with a high primordial helium mass fraction, . We confirm the detection of the high-ionization forbidden emission line [Fe v] λ4227 in the spectrum of Tol 1214–277.
Additionally, weak [Ne iv] λ4725, [Fe vi] λ5146, λ5177, and [Fe vii] λ5721, λ6087 emission lines are detected in the high-resolution spectrum of Tol 1214–277. The detection of these lines implies the presence of hard radiation with photon energy in the range ~4–8 Ryd. Emission lines are detected in the spectra of eight galaxies in the fields of Tol 1214–277 and Tol 65. Seven of these galaxies are background objects, while one galaxy has a redshift close to that of Tol 1214–277. Situated at a projected distance of ~14.5 kpc from Tol 1214–277, this galaxy is probably a companion of the BCD.