Proper motion and distances of stars in NGC 457. Left panel: Gaia EDR3 proper motion of stars in the open cluster NGC 457. Stars marked with small red dots or red circles are subject to selection criteria and are excluded from the histogram in the right panel. Massive stars are marked by open circles. In addition to the massive stars, we included stars with a membership probability ≥ 70% according to the WEBDA database. Right panel: Distribution of the Gaia DRЗ distances, computed from the inversion of the parallaxes. The sample star BD +57 247 (ID#10) is marked by a square.