Line identification and photometric history of the hot post-AGB star Hen 3−1013 (IRAS 14331−6435)

Abstract

We present a study of the high-resolution optical spectrum for the hot post-asymptotic giant branch (post-AGB) star, Hen 3−1013, identified as the optical counterpart of the infrared source IRAS 14331−6435. For the first time, the detailed identifications of the observed absorption and emission features in the wavelength range 3700–9000 Å is carried out. Absorption lines of H I, He I, C I, N I, O I, Ne I C II, N II, O II, Si II, S II, Ar II, Fe II, Mn II, Cr II, Ti II, Co II, Ni II, S III, Fe III, and S IV were detected. From the absorption lines, we derived heliocentric radial velocities of Vr = −29.6 ± 0.4 km s−1. We have identified emission permitted lines of O I, N I, Fe II, Mg II, Si II, and Al II. The forbidden lines of [N I], [Fe II], [Cr II], and [Ni II] have been identified also. Analysis of [Ni II] lines in the gaseous shell gives an estimate for the electron density Ne ∼ 107 cm−3 and the expansion velocity of the nebula Vexp = 12 km s−1. The mean radial velocity as measured from emission features of the envelope is Vr = −36.0 ± 0.4 km s−1. The Balmer lines H Α, H Β, and H Γ show P Cyg behaviour which indicate ongoing post-AGB mass loss. Based on ASAS and ASAS-SN data, we have detected rapid photometric variability in Hen 3−1013 with an amplitude up to 0.2 mag in the V band. The star’s low-resolution spectrum underwent no significant changes from 1994 to 2012. Based on archival data, we have traced the photometric history of the star over more than 100 yr. No significant changes in the star brightness have been found.