Informace o publikaci
Searching for shell stars in LAMOST DR4 by probing the Fe 42 multiplet lines
| Autoři | |
|---|---|
| Rok publikování | 2022 |
| Druh | Článek v odborném periodiku |
| Časopis / Zdroj | Monthly Notices of the Royal Astronomical Society |
| Fakulta / Pracoviště MU | |
| Citace | |
| www | |
| Doi | http://dx.doi.org/10.1093/mnras/stac2978 |
| Klíčová slova | techniques: spectroscopic; stars: chemically peculiar; circumstellar matter; stars: variables: general |
| Popis | Shell stars, in particular the cooler ones, often do not show conspicuous Balmer-line emission and may consequently be missed in surveys that specifically search for emission signatures in the H alpha line. This work is aimed at identifying stars with shell-signatures via a search for strong Fe ii multiplet 42 lines at lambda lambda 4924, 5018, 5169 angstrom in archival LAMOST spectra. Candidates were selected by probing the Fe ii (42) lines in the spectra of a sample of colour-preselected early-type stars using a modified version of the MKCLASS code and then categorized by visual inspection of their spectra. We identified 75 stars showing conspicuous shell features, 43 Am/CP1 stars, 12 Ap/CP2 stars, and three objects with composite spectra. Spectral types and equivalent width measurements of the Fe ii (42) lines are presented for the sample of shell stars. Except for three objects, all shell stars appear significantly removed from the ZAMS in the colour-magnitude diagram, which is likely due to extinction by circumstellar material. We find a correlation between the equivalent width of the lambda 5169 angstrom line and the distance to the locus of the main-sequence stars (the larger the IR-excess, the stronger the lambda 5169 angstrom line) and studied the variability of the shell star sample using Transiting Exoplanet Survey Satellite data, identifying a very high proportion of double stars. All but 14 shell stars are new discoveries, which highlights the efficiency of the here presented novel approach to identify stars with subtle shell features. This study may be used as a blueprint for discovering these objects in massive spectral data bases. |