Unknown wavelength splitting of the N V 4945 Å multiplet

Determine the wavelength splitting of the N V (nitrogen V) 4945 Å multiplet to enable accurate modeling of the N V 4945 Å emission feature in the O(He) star Gaia DR3 and similar hot hydrogen-deficient pre-white dwarfs.

Background

In the analysis of the O(He) star Gaia DR3, the nitrogen abundance was constrained using N V lines, but the modeled emission strength of the N V 4945 Å feature did not match the observations. The authors attribute this mismatch to missing atomic data: the wavelength splitting of the 4945 Å N V multiplet is not known, which prevents reliable spectral modeling and abundance determination.

Accurate knowledge of the multiplet’s wavelength splitting is essential for reproducing the observed emission and for robust atmospheric parameter inference in hot hydrogen-deficient stars.