New Short-Period δ Scuti Stars in OGLE-IV Fields toward the Galactic Bulge

We report the classification of 24 puzzling short-period variable stars located in OGLE-IV Galactic bulge fields. The stars are low-amplitude (<0.05 mag) multi-periodic objects with dominant periods between 22 min and 54 min whose type could not have been unambiguously established based on photometry only. A low-resolution spectroscopic follow-up observations have shown that all the objects are main sequence A/F-type stars. Thus, all the variables are δ Sct-type pulsators. We have added them to the OGLE-IV Collection of Variable Stars.