On the metallicities of UM 133, UM 283 and UM 382

Special Astrophysical Observatory, Nizhnij Arkhyz, Karachai-Circessia, 357147, Russia

We present the results of spectrophotometry of two Blue Compact Galaxies (BCG) known from earlier studies as very metal-poor objects. Well measured [O III] line $\lambda$ 4363 Å allows to deduce the temperature in H II regions and get reliable abundances of chemical elements. O-abundance of UM 133 is 12+log(O/H) = 7.65 $\pm$ 0.04, close to the claimed earlier value of 7.63. In its spectrum we detected also the blue bump characteristic of WR galaxies. Its H $\alpha$ velocity curve indicates the range close to that derived from H I 21 cm data. The data is inconsistent with NED information on two components with discrepant radial velocities. UM 382, according to our data, is significantly more metal-rich: its 12+log(O/H) = 7.76 $\pm$ 0.07 in comparison to the cited earlier value 7.45. UM 283 seems have got its low 12+log(O/H) = 7.59 due to a misprint. We used its earlier published emission line intensities and derived instead the value of 7.95. Thus the latter two galaxies should NOT be considered as extremely metal-poor BCGs.

galaxies: abundances - galaxies: photometry - galaxies: individual (UM 133, UM 283, UM 382)

On the metallicities of UM 133, UM 283 and UM 382

Abstract: