2008A&A...489..377C


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.04CET19:25:47

2008A&A...489..377C - Astronomy and Astrophysics, volume 489, 377-394 (2008/10-1)

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.

CHARPINET S., VAN GROOTEL V., REESE D., FONTAINE G., GREEN E.M., BRASSARD P. and CHAYER P.

Abstract (from CDS):

We present a stringent test on the forward modeling technique in asteroseismology by confronting the predictions of a detailed seismic analysis of the pulsating subdwarf component in the unique close eclipsing binary system PG 1336-018 with those derived independently from modeling the binary light curve of the system. We also take advantage of the observed rotationally-split rich period spectrum to investigate the internal dynamics of the pulsating component in this system expected to be tidally locked. We carry out numerical exercises based on the double optimization technique that we developed within the framework of the forward modeling approach in asteroseismology. We use a recently updated version that now incorporates the effects of stellar rotation on the pulsation properties. We thus search in parameter space for the optimal model that objectively leads to the best simultaneous match of the 25 periods (including rotationally-split components) observed in PG 1336-018. For the first time, we also attempt to precisely reconstruct the internal rotation profile of the pulsator from its oscillations. Our principal result is that our seismic model, which closely reproduces the observed periods, is remarkably consistent with one of the best-fitting possible solutions uncovered independently from the binary light curve analysis, in effect pointing to the correct one. The latter indicates a mass of M*=0.466±0.006M and a radius of R*=0.15±0.01R for the sdB star. In comparison, our seismic analysis, combined to high-quality time-averaged spectroscopy, leads to the following estimates of the basic structural parameters of the sdB component: M*=0.459±0.005M, R*=0.151±0.001R, logg=5.739±0.002, Teff=32740±400K, and log(Menv/M*)=-4.54±0.07. We also find strong evidence that the sdB star has reached spin-orbit synchronism and rotates as a solid body down to at least r∼0.55R*. We further estimate that higher-order perturbation effects due to rotation and tidal deformation of the star are insufficient to alter in a significant way the proposed asteroseismic solution itself (i.e., the derived structural parameters and rotation properties). Future efforts to improve further the accuracy of the seismic models will clearly have to incorporate such effects, however. We conclude that our approach to the asteroseismology of sdB stars has passed a fundamental test with this analysis of PG 1336-018. The structural parameters and inferences about the internal dynamics of this star derived in the present paper through this approach should rest on very solid grounds. More generally, our results underline the power and usefulness of the forward modeling method in asteroseismology, despite historical misgivings about it.

Abstract Copyright:

Journal keyword(s): stars: binaries: close - stars: subdwarfs - stars: oscillations - stars: interiors - stars: rotation - stars: individual: PG 1336-018

Simbad objects: 17

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Number of rows : 17

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 PG 0014+068 HS* 00 16 54.2524890907 +07 04 30.045980038   15.3       sdO 69 1
2 Feige 11 HS* 01 04 21.6744758331 +04 13 37.051396308 10.847 11.826 12.065 12.183 12.324 sdB2VIHe4 113 0
3 V* IQ Cam HS* 04 26 06.8650071405 +54 28 17.100742176 14.21 14.86 14.66     sdB 58 0
4 V* V470 Cam HS* 07 10 42.0512018720 +66 55 43.520280054           sdB+dM 97 1
5 V* DT Lyn HS* 09 14 55.3782483821 +45 23 41.396924047   14.92       sdBO 26 0
6 V* UY Sex HS* 10 50 02.8264873492 -00 00 36.880346331 12.063 13.184 13.474 13.606 13.769 sdO9VIIHe6 151 0
7 Feige 48 HS* 11 47 14.4977747924 +61 15 31.790488292   13.12 13.28     sdB 111 0
8 PG 1219+534 HS* 12 21 29.0915970330 +53 04 36.796970097   12.41       sdB 79 1
9 BD-07 3477 HS* 12 44 20.2386520980 -08 40 16.848587212   10.46 10.594 10.895   sdB2VIIHe3 257 1
10 PG 1325+102 HS* 13 27 48.5602550889 +09 54 51.048576366   13.73 13.98 14.29   sdBO 54 1
11 V* NY Vir HS* 13 38 48.1466489725 -02 01 49.209465866   13.43 13.66 13.75   sdB1VIIHe1 197 1
12 V* V361 Hya ** 14 05 33.00 -27 01 34.1   15.45 15.26 15.16   sdB+ 110 0
13 PG 1716+426 HS* 17 18 03.8584285848 +42 34 12.566188858   13.69 13.97     sdB2VIIHe3 99 0
14 KPD 1930+2752 HS* 19 32 14.8086352823 +27 58 35.444970697 12.80 13.75 13.82     sdB 146 0
15 CD-40 13747 HS* 20 15 04.7874862110 -40 05 44.113745580 11.91 12.09 11.82     sdO 44 0
16 HS 2231+2441 HS* 22 34 21.4839930427 +24 56 57.390542495     14.20     sdB+dM 42 1
17 Balloon 90100001 HS* 23 15 21.4810383697 +29 05 01.429272894   11.90 12.30     sdB 79 0

    Equat.    Gal    SGal    Ecl

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2021.03.04-19:25:47

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