Variable Blue Straggler Stars in the Open Cluster NGC 6819 Observed in the Kepler “Superstamp” Field

0571209 - ASÚ 2024 RIV US eng J - Článek v odborném periodiku
Guzik, J. A. - Baran, A.S. - Sanjayan, S. - Németh, Péter - Hedlund, A. M. - Jackiewicz, J. - Dauelsberg, L. R.
Variable Blue Straggler Stars in the Open Cluster NGC 6819 Observed in the Kepler “Superstamp” Field.
Astronomical Journal. Roč. 165, č. 5 (2023), č. článku 188. ISSN 0004-6256. E-ISSN 1538-3881
Grant CEP: GA ČR(CZ) GA22-34467S
Institucionální podpora: RVO:67985815
Klíčová slova: Delta Scuti variable stars * asteroseismology * blue straggler stars
Obor OECD: Astronomy (including astrophysics,space science)
Impakt faktor: 5.3, rok: 2022
Způsob publikování: Open access

We present light curves and pulsation frequency analyses derived from custom photometric reductions for five confirmed cluster members-four blue stragglers and one star near the main-sequence turnoff. Two of these stars show a rich spectrum of delta Scuti pulsation modes, with 236 and 124 significant frequencies identified, respectively, while two stars show mainly low-frequency modes, characteristic of gamma Doradus variable stars. The fifth star, a known active X-ray binary, shows only several harmonics of two main frequencies. For the two delta Scuti stars, we use a frequency separation-mean density relation to estimate their mean densities, and then use these values along with their effective temperature to derive their stellar masses and radii. For the two stars showing low frequencies, we searched for period-spacing sequences that may be representative of gravity-mode or Rossby-mode sequences, but found no clear sequences. The common age for the cluster members, considered along with the frequencies, will provide valuable constraints for asteroseismic analyses, and may shed light on the origin of the blue stragglers.
Trvalý link: https://hdl.handle.net/11104/0342483