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Structural and core parameters of the hot B subdwarf KPD 1943+4058 as inferred from g-mode oscillations
Van Grootel, Valérie; Charpinet, Stéphane; Fontaine, Gilles et al.
2010Third Kepler Workshop
 

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Abstract :
[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 explain quite well 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 the 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 : Teff = 28,050 ± 470 K, log g = 5.520 ± 0.029, M∗ = 0.4964 ± 0.0013 M⊙, log (Menv/M∗) = −2.552 ± 0.070, log (1−Mcore/M∗) = −0.366 ± 0.010, and Xcore(C+O) = 0.2612 ± 0.0080. We additionally derive the age of the star since the Zero-Age EHB 18.4 ± 1.0 Myr, the radius R = 0.2026 ± 0.0070 R⊙, the luminosity L = 22.92 ± 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 = 1183 ± 93 pc.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Van Grootel, Valérie  ;  Laboratoire d'Astrophysique de Toulouse-Tarbes (LATT)
Charpinet, Stéphane
Fontaine, Gilles
Brassard, Pierre
Green, Elizabeth M
Randall, Suzanna K
Language :
English
Title :
Structural and core parameters of the hot B subdwarf KPD 1943+4058 as inferred from g-mode oscillations
Publication date :
June 2010
Event name :
Third Kepler Workshop
Event organizer :
Aarhus Universitet
Event place :
Aarhus, Denmark
Event date :
du 14 au 18 juin 2010
Audience :
International
Available on ORBi :
since 23 January 2012

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