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Paper: The Instability Strip of RRab Stars From LAMOST-Gaia Data
Volume: 529, RR Lyrae/Cepheid 2019: Frontiers of Classical Pulsators
Page: 147
Authors: Luo, C.; Liu, C.; Zhang, X.; Chen, X.; Sun, W.; Zhang, X.; Li, Y.; Zhang, C.; Tian, H.
Abstract: We compile 995 RRab samples from various literature and cross-match them with LAMOST to identify the boundaries of instability strip (IS) at red and blue edges and to associate them with metallicity. We find a significant gap at [Fe/H]=–0.5 dex, which separates the RRab stars into metal-poor and metal-rich groups. For the metal-poor group, the IS moves toward cooler Teff with declining [Fe/H]. The slopes, dTeff/d[Fe/H], are 192±19 K/dex and 354±51 K/dex for red and blue edges, respectively. For the metal-rich group, the blue edge of IS moves toward hotter Teff with declining [Fe/H], while the red edge is nearly independent on [Fe/H]. A similar trend is also confirmed in Teff–luminosity diagram. By comparing with various theoretical models of RRab stars, we find the correlation between IS and metallicity is not consistent with the theoretical model.
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