Kepler and TESS Observations of PG 1159-035

• Autores: Oliveira da Rosa, Gabriela; Kepler, S. O.; Corsico, Alejandro Hugo; Costa, J. E. S.; Hermes, J. J.; Kawaler, S. D.; Bell, Keaton J.; Montgomery, M. H.; Provencal, J. L.; Winget, D. E.; Handler, G.; Dunlap, Bart; Clemens, J. C.; Uzundag, Murat
• Año de publicación: 2022
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Pulsating variable stars; White dwarf stars; Asteroseismology
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

PG 1159-035 is the prototype of the PG 1159 hot (pre-)white dwarf pulsators. This important object was observed during the Kepler satellite K2 mission for 69 days in 59 s cadence mode and by the TESS satellite for 25 days in 20 s cadence mode. We present a detailed asteroseismic analysis of those data. We identify a total of 107 frequencies representing 32 ℓ = 1 modes, 27 frequencies representing 12 ℓ = 2 modes, and eight combination frequencies. The combination frequencies and the modes with very high k values represent new detections. The multiplet structure reveals an average splitting of 4.0 ± 0.4 μHz for ℓ = 1 and 6.8 ± 0.2 μHz for ℓ = 2, indicating a rotation period of 1.4 ± 0.1 days in the region of period formation. In the Fourier transform of the light curve, we find a significant peak at 8.904 ± 0.003 μHz suggesting a surface rotation period of 1.299 ± 0.002 days. We also present evidence that the observed periods change on timescales shorter than those predicted by current evolutionary models. Our asteroseismic analysis finds an average period spacing for ℓ = 1 of 21.28 ± 0.02 s. The ℓ = 2 modes have a mean spacing of 12.97 ± 0.4 s. We performed a detailed asteroseismic fit by comparing the observed periods with those of evolutionary models. The best-fit model has T eff = 129, 600 ± 11 100 K, M * = 0.565 ± 0.024M ⊙, and log g = 7.41 − 0.54 + 0.38 , within the uncertainties of the spectroscopic determinations. We argue for future improvements in the current models, e.g., on the overshooting in the He-burning stage, as the best-fit model does not predict excitation for all of the pulsations detected in PG 1159-035.
Fil: Oliveira da Rosa, Gabriela. Universidade Federal do Rio Grande do Sul; Brasil
Fil: Kepler, S. O.. Universidade Federal do Rio Grande do Sul; Brasil
Fil: Corsico, Alejandro Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina
Fil: Costa, J. E. S.. Universidade Federal do Rio Grande do Sul; Brasil
Fil: Hermes, J. J.. Boston University; Estados Unidos
Fil: Kawaler, S. D.. University of Iowa; Estados Unidos
Fil: Bell, Keaton J.. University Of Washington; Estados Unidos
Fil: Montgomery, M. H.. University of Texas at Austin; Estados Unidos
Fil: Provencal, J. L.. University Of Delaware; Estados Unidos
Fil: Winget, D. E.. University of Texas at Austin; Estados Unidos
Fil: Handler, G.. Nicolaus Copernicus Astronomical Center Of The Polish Academy Of Sciences; Polonia
Fil: Dunlap, Bart. Mcdonald Observatory; Estados Unidos. University of Texas at Austin; Estados Unidos
Fil: Clemens, J. C.. University of North Carolina; Estados Unidos
Fil: Uzundag, Murat. Universidad de Valparaíso; Chile