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

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F23%3A00571209" target="_blank" >RIV/67985815:_____/23:00571209 - isvavai.cz</a>
Result on the web
<a href="https://hdl.handle.net/11104/0342483" target="_blank" >https://hdl.handle.net/11104/0342483</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.3847/1538-3881/acc0f0" target="_blank" >10.3847/1538-3881/acc0f0</a>

Result language
angličtina
Original language name
Variable Blue Straggler Stars in the Open Cluster NGC 6819 Observed in the Kepler “Superstamp” Field
Original language description
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.
Czech name
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Czech description
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Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10308 - Astronomy (including astrophysics,space science)

Project
<a href="/en/project/GA22-34467S" target="_blank" >GA22-34467S: Binary interaction on the red giant branch: Hot subdwarfs as a test case.</a><br>
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2023
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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