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Shell stars, in particular the cooler ones, often do not show conspicuousBalmer-line emission and may consequently be missed in surveys thatspecifically search for emission signatures in the Halpha line. The presentwork is aimed at identifying stars with shell-signatures via a search forstrong FeII multiplet 42 lines at 4924, 5018, 5169A in archival LAMOST spectra.Candidates were selected by probing the FeII 42 lines in the spectra of asample of colour-preselected early-type stars using a modified version of theMKCLASS code and then categorised by visual inspection of their spectra. Weidentified 75 stars showing conspicuous shell features, 43 Am/CP1 stars, 12Ap/CP2 stars, and three objects with composite spectra. Spectral types andequivalent width measurements of the FeII 42 lines are presented for the sampleof shell stars. Except for three objects, all shell stars appear significantlyremoved from the ZAMS in the colour-magnitude diagram, which is likely due toextinction by circumstellar material. We find a correlation between theequivalent width of the 5169A line and the distance to the locus of themain-sequence stars (the larger the IR-excess, the stronger the 5169A line) andstudied the variability of the shell star sample using TESS data, identifying avery high proportion of double stars. All but 14 shell stars are newdiscoveries, which highlights the efficiency of the here presented novelapproach to identify stars with subtle shell features. This study may be usedas a blueprint for discovering these objects in massive spectral databases.

Searching for shell stars in LAMOST DR4 by probing the Fe 42 multiplet lines