TY - JOUR
T1 - Early asteroseismic results from kepler
T2 - Structural and core parameters of the hot b subdwarf kpd 1943+4058 as inferred from g-mode oscillations
AU - Van Grootel, V.
AU - Charpinet, S.
AU - Fontaine, G.
AU - Brassard, P.
AU - Green, E. M.
AU - Randall, S. K.
AU - Silvotti, R.
AU - Østensen, R. H.
AU - Kjeldsen, H.
AU - Christensen-Dalsgaard, J.
AU - Borucki, W. J.
AU - Koch, D.
PY - 2010/8/1
Y1 - 2010/8/1
N2 - 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 lowdegree (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): T eff = 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±1.0Myr, the radius R=0.203±0.007R⊙, 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.
AB - 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 lowdegree (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): T eff = 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±1.0Myr, the radius R=0.203±0.007R⊙, 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.
KW - Color figure
KW - Interiors-stars
KW - Machine-readable table
KW - Oscillations- subdwarfs Online-only material
KW - Stars
UR - http://www.scopus.com/inward/record.url?scp=78249240601&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78249240601&partnerID=8YFLogxK
U2 - 10.1088/2041-8205/718/2/L97
DO - 10.1088/2041-8205/718/2/L97
M3 - Article
AN - SCOPUS:78249240601
VL - 718
SP - L97-L101
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 2 PART 2
ER -