Age and metallicity of a globular cluster in the dwarf spheroidal galaxy DDO 78

¹ Special Astrophysical Observatory, Russian Academy of Sciences, N.Arkhyz, KChR, 369167, Russia
² Isaac Newton Institute, Chile, SAO Branch
³ Sternberg Astronomical Institute, Universitetskij Prospect 13, 119992 Moscow, Russia
⁴ Isaac Newton Institute, Chile, Moscow Branch

Corresponding author: M. E. Sharina, sme@luna.sao.ru

Received: 22 May 2002
Accepted: 5 September 2002

Abstract

We present the results of moderate resolution spectroscopy for a globular cluster in the M81 group dwarf spheroidal galaxy DDO 78. The DDO 78 globular cluster, 4 Milky Way globular clusters, spectroscopic and radial velocity standards were observed with the Long-slit spectrograph of the 6-m telescope (SAO RAS, Russia). Lick spectrophotometric indices were determined in the bandpasses adopted by Burstein et al. (1984). We have derived the mean metallicity of the globular cluster in DDO78 to be [Fe/H]  dex by taking the weighted mean of metallicities obtained from the strength of several absorption features. We have estimated an age for the globular cluster of 9–12 Gyr similar to that found for the Galactic globular cluster NGC 362, which resembles the DDO 78 cluster in its chemical abundance and integrated spectrophotometric properties.