The QSO B234 and the irregular galaxy NGC 4861 - Examples of isolated extragalactic H II regions with low helium abundances
Line fluxes are presented for the QSO B234 and for the nucleus of the peculiar galaxy NGC 4861 and are used to derive physical parameters for the excited gas and abundances of helium, oxygen, nitrogen, neon, and sulfur relative to hydrogen. The values derived are found to be similar to those of typical "isolated extragalactic H II regions" (IEHRs) and well below what is considered to be normal. The helium abundance of both objects is below the average for the IEHRs and close to the primordial value derived by French in his study of these objects.The line profiles and line ratios of B234 are typical of IEHRs and at variance with those of QSOs. Although the luminosity of B234 is high for an H II-region-type object, it is not excessively so. We therefore conclude that B234 is, in fact, a luminous, distant IEHR rather than a QSO. The stellar appearance of B234 on the Palomar Sky Survey does not offer serious problems for this interpretation.