Deep asteroseismic sounding of the compact hot B subdwarf pulsator KIC02697388 from Kepler time series photometry

被引:72
作者
Charpinet, S. [1 ,2 ]
Van Grootel, V. [3 ]
Fontaine, G. [4 ]
Green, E. M. [5 ]
Brassard, P. [4 ]
Randall, S. K. [6 ]
Silvotti, R. [7 ]
Ostensen, R. H. [8 ]
Kjeldsen, H. [9 ]
Christensen-Dalsgaard, J. [9 ]
Kawaler, S. D. [10 ]
Clarke, B. D. [11 ]
Li, J. [11 ]
Wohler, B. [12 ]
机构
[1] Univ Toulouse, UPS OMP, IRAP, Toulouse, France
[2] CNRS, IRAP, F-31400 Toulouse, France
[3] Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium
[4] Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada
[5] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA
[6] ESO, D-85748 Garching, Germany
[7] INAF, Osservatorio Astron Torino, I-10025 Pino Torinese, Italy
[8] Katholieke Univ Leuven, Inst Sterrenkunde, B-3001 Louvain, Belgium
[9] Aarhus Univ, Dept Phys & Astron, DK-8000 Aarhus C, Denmark
[10] Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA
[11] NASA, SETI Inst, Ames Res Ctr, Moffett Field, CA 94035 USA
[12] NASA, Orbital Sci Corp, Ames Res Ctr, Moffett Field, CA 94035 USA
基金
加拿大自然科学与工程研究理事会;
关键词
stars: oscillations; stars: interiors; stars: horizontal-branch; subdwarfs; stars: individual: KIC02697388; BLANKETED MODEL ATMOSPHERES; DIGITAL SKY SURVEY; DRIVING MECHANISM; SDB STARS; PARAMETERS; DISCOVERY; ORIGIN; OSCILLATIONS; STABILITY;
D O I
10.1051/0004-6361/201016412
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Context. Contemporary high precision photometry from space provided by the Kepler and CoRoT satellites generates significant breakthroughs in terms of exploiting the long-period, g-mode pulsating hot B subdwarf (sdBV(epsilon)) stars with asteroseismology. Aims. We present a detailed asteroseismic study of the sdBV(s) star KIC02697388 monitored with Kepler, using the rich pulsation spectrum uncovered during the similar to 27-day-long exploratory run Q2.3. Methods. We analyse new high-S/N spectroscopy of KIC02697388 using appropriate NLTE model atmospheres to provide accurate atmospheric parameters for this star. We also reanalyse the Kepler light curve using standard prewhitening techniques. On this basis, we apply a forward modelling technique using our latest generation of sdB models. The simultaneous match of the independent periods observed in KIC02697388 with those of models leads objectively to the identification of the pulsation modes and, more importantly, to the determination of some of the parameters of the star. Results. The light curve analysis reveals 43 independent frequencies that can be associated with oscillation modes. All the modulations observed in this star correspond to g-mode pulsations except one high-frequency signal, which is typical of a p-mode oscillation. Although the presence of this p-mode is surprising considering the atmospheric parameters that we derive for this cool sdB star (T-eff = 25 395 +/- 227 K, log g = 5.500 +/- 0.031 (cgs), and log N(He)/N(H) = -2.767 +/- 0.122), we show that this mode can be accounted for particularly well by our optimal seismic models, both in terms of frequency match and nonadiabatic properties. The seismic analysis leads us to identify two model solutions that can both account for the observed pulsation properties of KIC02697388. Despite this remaining ambiguity, several key parameters of the star can be derived with stringent constraints, such as its mass, its H-rich envelope mass, its radius, and its luminosity. We derive the properties of the core proposing that it is a relatively young sdB star that has burnt less than similar to 34% (in mass) of its central helium and has a relatively large mixed He/C/O core. This latter measurement is in line with the trend already uncovered for two other g-mode sdB pulsators analysed with asteroseismology and suggests that extra mixing is occurring quite early in the evolution of He cores on the horizontal branch. Conclusions. Additional monitoring with Kepler of this particularly interesting sdB star should reveal the inner properties of KIC02697388 and provide important information about the mode driving mechanism and the helium core properties.
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页数:20
相关论文
共 60 条
[1]  
Baglin A., 2006, The CoRoT Mission Pre-Launch Status-Stellar Seismology and Planet Finding, V1306, P33
[2]   The pulsating hot subdwarf Balloon 090100001: results of the 2005 multisite campaign [J].
Baran, A. ;
Oreiro, R. ;
Pigulski, A. ;
Hernandez, F. Perez ;
Ulla, A. ;
Reed, M. D. ;
Rodriguez-Lopez, C. ;
Moskalik, P. ;
Kim, S-L. ;
Chen, W-P. ;
Crowe, R. ;
Siwak, M. ;
Armendarez, L. ;
Binder, P. M. ;
Choo, K-J. ;
Dye, A. ;
Eggen, J. R. ;
Garrido, R. ;
Gonzalez Perez, J. M. ;
Harms, S. L. ;
Huang, F-Y. ;
Koziel, D. ;
Lee, H-T. ;
MacDonald, J. ;
Fox Machado, L. ;
Monserrat, T. ;
Stevick, J. ;
Stewart, S. ;
Terry, D. ;
Zhou, A-Y. ;
Zola, S. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2009, 392 (03) :1092-1105
[3]  
BARAN AS, 2011, MNRAS IN PRESS
[4]   FUSE determination of abundances in long-period pulsating V1093 Her (PG 1716+426) stars [J].
Blanchette, J. -P. ;
Chayer, P. ;
Wesemael, F. ;
Fontaine, G. ;
Fontaine, M. ;
Dupuis, J. ;
Kruk, J. W. ;
Green, E. M. .
ASTROPHYSICAL JOURNAL, 2008, 678 (02) :1329-1341
[5]   Discovery and asteroseismological analysis of the pulsating sdB star PG 0014+067 [J].
Brassard, P ;
Fontaine, G ;
Billères, M ;
Charpinet, S ;
Liebert, J ;
Saffer, RA .
ASTROPHYSICAL JOURNAL, 2001, 563 (02) :1013-1030
[6]  
Brassard P, 2010, AIP CONF PROC, V1273, P259, DOI 10.1063/1.3527817
[7]   New results on the sdB star PG 0014+067 [J].
Brassard, P. ;
Fontaine, G. .
16TH EUROPEAN WHITE DWARFS WORKSHOP, 2009, 172
[8]  
Brassard P, 2008, ASTR SOC P, V392, P261
[9]   Testing the forward modeling approach in asteroseismology - II. Structure and internal dynamics of the hot B subdwarf component In the close eclipsing binary system PG 1336-018 [J].
Charpinet, S. ;
Van Grootel, V. ;
Reese, D. ;
Fontaine, G. ;
Green, E. M. ;
Brassard, P. ;
Chayer, P. .
ASTRONOMY & ASTROPHYSICS, 2008, 489 (01) :377-394
[10]   A driving mechanism for the newly discovered class of pulsating subdwarf B stars [J].
Charpinet, S ;
Fontaine, G ;
Brassard, P ;
Chayer, P ;
Rogers, FJ ;
Iglesias, CA ;
Dorman, B .
ASTROPHYSICAL JOURNAL, 1997, 483 (02) :L123-L126