We separately assess elemental abundances in active galactic nuclei's (AGNs) broad and
narrow emission line regions (BLR and NLR), based on a critical assessment of published …

Stars are likely to form or to be captured in active galactic nucleus (AGN) discs. Their mass
reaches an equilibrium when their rate of accretion is balanced by that of wind. If the …

Modern cosmology is broadly based on the Cosmological principle, which assumes
homogeneity and isotropy as its foundational pillars. Thus, there is not much debate about …

Population III stars were the first stars to form after the Big Bang and are believed to have
made the earliest contribution to the metal content of the universe beyond the products of the …

We present a reassessment of the radial abundance gradients of He, C, N, O, Ne, S, Cl, and
Ar in the Milky Way using the deep optical spectra of 42 H ii regions presented in Arellano …

Using a new sample of extremely metal poor systems, the EMPRESS survey has recently
reported a primordial helium abundance that is 3 σ smaller than the prediction from the …

ABSTRACT The theory of Big Bang nucleosynthesis, coupled with an estimate of the
primordial deuterium abundance (D/H) pr, offers insights into the baryon density of the …

For the first time, the helium abundance relative to hydrogen (He/H), which relied on direct
measurements of the electron temperature, has been derived in the narrow line regions …

We revisit the state of the light element abundances from big bang nucleosynthesis in early
2024 with particular focus on the derived baryon abundance. We find that the largest …

Context. In stars, metallicity is usually traced using Fe, while in nebulae, O serves as the
preferred proxy. Both elements have different nucleosynthetic origins and are not directly …