2010ApJ...718L..97V -
Astrophys. J., 718, L97-L101 (2010/August-1)
Early asteroseismic results from Kepler: structural and core parameters of the hot b subdwarf KPD 1943+4058 as inferred from g-mode oscillations.
VAN GROOTEL V., CHARPINET S., FONTAINE G., BRASSARD P., GREEN E.M., RANDALL S.K., SILVOTTI R., OSTENSEN R.H., KJELDSEN H., CHRISTENSEN-DALSGAARD J., BORUCKI W.J. and KOCH D.
Abstract (from CDS):
We present a seismic analysis of the pulsating hot B subdwarf KPD 1943+4058 (KIC 005807616) on the basis of the long-period, gravity-mode pulsations recently uncovered by Kepler. This is the first time that g-mode seismology can be exploited quantitatively for stars on the extreme horizontal branch, all previous successful seismic analyses having been confined so far to short-period, p-mode pulsators. We demonstrate that current models of hot B subdwarfs can quite well explain the observed g-mode periods, while being consistent with independent constraints provided by spectroscopy. We identify the 18 pulsations retained in our analysis as low-degree (ℓ = 1 and 2), intermediate-order (k = -9 through -58) g-modes. The periods (frequencies) are recovered, on average, at the 0.22% level, which is comparable to the best results obtained for p-mode pulsators. We infer the following structural and core parameters for KPD 1943+4058 (formal fitting uncertainties only): Teff= 28,050 ± 470 K, log g = 5.52±0.03, M*= 0.496±0.002 M☉, log (Menv/M *) = -2.55±0.07, log (1 - Mcore/M*) = -0.37±0.01, and Xcore(C+O) = 0.261±0.008. We additionally derive the age of the star since the zero-age extended horizontal branch 18.4±1.0 Myr, the radius R = 0.203±0.007 R ☉, the luminosity L = 22.9±3.13 L☉, the absolute magnitude MV= 4.21±0.11, the reddening index E(B - V) = 0.094±0.017, and the distance d = 1180±95 pc.
Abstract Copyright:
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Journal keyword(s):
stars: individual: KPD 1943+4058 - stars: interiors - stars: oscillations - subdwarfs
VizieR on-line data:
<Available at CDS (J/ApJ/718/L97): table1.dat table2.dat>
CDS comments:
In paragr 3.4: KPD 1943+4958 is a misprint for KPD 1943+4058.
Simbad objects:
1
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