Reference : Early asteroseismic results from Kepler: structural and core parameters of the hot B ...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/108703
Early asteroseismic results from Kepler: structural and core parameters of the hot B subdwarf KPD 1943+4058 as inferred from g-mode oscillations
English
Van Grootel, Valérie mailto [Laboratoire d'Astrophysique de Toulouse-Tarbes (LATT) > > > >]
Charpinet, Stéphane [ > > ]
Fontaine, Gilles [ > > ]
Brassard, Pierre [ > > ]
Green, Elizabeth M. [ > > ]
Randall, Suzanna K. [ > > ]
Silvotti, Roberto [ > > ]
Ostensen, Roy H. [ > > ]
Kjeldsen, Hans [ > > ]
Christensen-Dalsgaard, Joergen [ > > ]
Borucki, William J. [ > > ]
Koch, David [ > > ]
1-Aug-2010
Astrophysical Journal Letters
IOP Publishing
718
L97-L101
Yes (verified by ORBi)
International
2041-8205
2041-8213
Bristol
United Kingdom
[en] stars: individual (KPD 1943+4058) ; stars: interiors ; stars: oscillations
[en] 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.
http://hdl.handle.net/2268/108703

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