Examinando por Autor "Bonatto, Charles J"

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    The Gaia Parallax Discrepancy for the Cluster Pismis 19 and Separating δ Scutis from Cepheids
    (Institute of Physics, 0025) Majaess, Daniel; Bonatto, Charles J; Turner, David G.; Saito, Roberto K.; Minniti, Dante; Moni Bidin, Christian; González-Díaz, Danilo; Alonso-Garcia, Javier; Bono, Giuseppe k; Braga, Vittorio F. l;; Navarro, Maria G; Carraro, Giovanni
    Pre-Gaia distances for the open cluster Pismis 19 disagree with Gaia parallaxes. A Two Micron All Sky Survey (2MASS) JKs red clump distance was therefore established for Pismis 19 (2.90 ± 0.15 kpc), which reaffirms that zero-point corrections for Gaia are required. OGLE GD-CEP-1864 is confirmed as a member of Pismis 19 on the basis of DR3 proper motions and its 2MASS+Vista Variables in the Vía Láctea color-magnitude position near the tip of the turnoff. That 0.3 day variable star is likely a δ Scuti rather than a classical Cepheid. The case revealed a pertinent criterion to segregate those two populations in tandem with the break in the Wesenheit Leavitt Law (≃0.5 day). Just shortward of that period discontinuity are δ Scutis, whereas beyond the break lie first overtone classical Cepheids mostly observed beyond the first crossing of the instability strip. © 2025. The Author(s). Published by the American Astronomical Society.