EARLY ASTEROSEISMIC RESULTS FROM KEPLER: STRUCTURAL AND CORE PARAMETERS OF THE HOT B SUBDWARF KPD 1943+4058 AS INFERRED FROM g-MODE OSCILLATIONS

摘要: We present a seismic analysis of the pulsating hot B subdwarf KPD 1943+4058 (KIC 005807616) on basis long-period, gravity-mode pulsations recently uncovered by Kepler. This is first time that g-mode seismology can be exploited quantitatively for stars extreme horizontal branch, all previous successful analyses having been confined so far to short-period, p-mode pulsators. demonstrate current models subdwarfs quite well explain observed periods, while being consistent with independent constraints provided spectroscopy. identify 18 retained in our as low-degree (l = 1 and 2), intermediate-order (k –9 through –58) g-modes. The periods (frequencies) are recovered, average, at 0.22% level, which comparable best results obtained infer following structural core parameters (formal fitting uncertainties only): T eff 28,050 ± 470 K, log g 5.52 0.03, M * 0.496 0.002 ☉, (M env/M *) –2.55 0.07, (1 – core/M –0.37 0.01, X core(C+O) 0.261 0.008. additionally derive age star since zero-age extended branch 18.4 1.0 Myr, radius R 0.203 0.007 luminosity L 22.9 3.13 absolute magnitude MV 4.21 0.11, reddening index E(B V) 0.094 0.017, distance d 1180 95 pc.