A Spectroscopic Study of Weak Metallic Emission Lines in a B3V Star iota Her

TL;DR

This study catalogs weak emission lines in the B3V star iota Her using high-resolution spectroscopy, identifying new lines and comparing them with another star to explore abundance differences and spectral line behaviors.

Contribution

It provides the first identification of certain emission lines in normal B-type stars and compares spectral features with a chemically peculiar star to understand abundance effects.

Findings

Identified 207 weak emission lines in iota Her.

First detection of C II, N I, Cr II, Mn II, Ni II emission lines in normal B stars.

Differences in emission line presence reflect abundance variations between stars.

Abstract

We present a list of weak emission lines (WELs) observed in a sharp-lined B3 V star {\iota} Her (HD 160762) using high resolution (R = 65000) and high SN (~1300) spectral data. The list covers a spectral region between 4900A and 10000A. We register 207 WELs in this star and identified 190 lines including ten ions (nine elements). Emission lines of C II, N I, Cr II, Mn II, and Ni II have been identified among normal B-type stars for the first time. 17 emission lines remain unidentified. We compare our list with the published list of WELs for 3 Cen A (Wahlgren and Hubrig 2004) and found that numbers of detected emission lines reflect differences in abundance between these two stars. We detect 13 C I emission lines in iota Her (normal in C), while only one C I emission line is found in 3 Cen A (deficient in C). Many emission lines of P II and Cu II have been detected in 3 Cen A (overabundant in both P and Cu), while no emission line of these ions has been found in {\iota} Her. Many emission lines of Fe II are visible in the shorter wavelength side of 6000 A in iota Her, while these emission lines are missing in 3 Cen A. Close inspections of spectral data of 3 Cen A reveal that apparently missing Fe II lines appear as absorption lines in this star. Because these two stars have nearly the same atmospheric parameters (Teff and log g), a physical interpretation which is independent on these two parameters is needed to account for this observation.