# 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.

## Key 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.

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Source: https://tomesphere.com/paper/1902.01059