Short-Period BLG delta Scuti

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

P. Pietrukowicz, M. Ratajczak, I. Soszyński, A. Udalski, M.K. Szymański, K. Ulaczyk, R. Poleski, S. Kozłowski, J. Skowron, D.M. Skowron, P. Mróz, K. Rybicki, P. Iwanek, M. Wrona, and M. Gromadzki
Acta Astronomica, 72, 161 (arXiv:2212.07355)

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 and 54 min whose type could not have been unambiguously established based on photometry only. A low-resolution spectroscopic follow-up has shown that all the objects are main sequence A/F-type stars. Thus, all the variables are delta Sct-type pulsators. We have added them to the OGLE-IV Collection of Variable Stars.

short-period delta Sct spectra
Phased OGLE I-band light curves (left column), V-I color vs I magnitude diagrams (middle column), and EFOSC2/NTT low-resolution spectra (right column) of 6 (out of 24) discovered δ Sct stars.
short-period delta Sct HR
Positions of the 24 observed stars in the Teff vs. logg plane. All the objects are located in the area for main sequence stars of spectral type A and early F.

OGLE photometric data are available to the astronomical community from the OGLE Internet Archive and interactive on-line inteface OCVS (OGLE Collection of Variable Stars) search form.

PLEASE cite the following paper when using the data or referring to these OGLE results:
Pietrukowicz et al., 2022, Acta Astronomica, 72, 161 (arXiv:2212.07355)

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