A precision study of two eclipsing white dwarf plus M dwarf binaries
A precision study of two eclipsing white dwarf plus M dwarf binaries
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DOI：
10.1111/j.1365-2966.2011.20251.x
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发表时间：
2011-11
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通讯作者：
S. G. Parsons;Tom Marsh;B. Gänsicke;A. Rebassa-Mansergas;V. Dhillon;S. Littlefair;C. Copperwheat;R. Hickman;M. Burleigh;P. Kerry;D. Koester;A. N. G'omez-Mor'an;S. Pyrzas;C. Savoury;M. Schreiber;L. Schmidtobreick;A. Schwope;P. Steele;Claus Tappert
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作者：
S. G. Parsons;Tom Marsh;B. Gänsicke;A. Rebassa-Mansergas;V. Dhillon;S. Littlefair;C. Copperwheat;R. Hickman;M. Burleigh;P. Kerry;D. Koester;A. N. G'omez-Mor'an;S. Pyrzas;C. Savoury;M. Schreiber;L. Schmidtobreick;A. Schwope;P. Steele;Claus Tappert
我们使用X-射手光谱，ULTRACAM高速测光和SOFI近红外测光的组合来测量食后共同信封双星SDSSJ 121258.25 -012310.1和GKVir的两个组件的质量和半径。对于这两个系统，我们测量的引力红移的白色矮星（WD）和联合收割机它与光变曲线模型拟合，以确定倾角，质量和半径。对于SDSSJ 1212 -0123，我们得到倾角i= 857 ± 05，质量M WD= 0.439 ± 0.002M <$，M sec= 0.273 ± 0.002M <$，半径R WD= 0.0168 ± 0.0003R <$，R sec= 0.306 ± 0.007R <$。对于GKVir，我们得到倾角i= 895°± 06，质量M WD= 0.564 ± 0.014M <$，M sec= 0.116 ± 0.003M <$，半径R WD= 0.0170 ± 0.0004R <$，R sec= 0.155 ± 0.003R <$。GKVir中WD的质量和半径与50000 K碳氧（CO）芯WD的演化模型一致。虽然SDSSJ 1212 -0123中WD的质量和半径与CO核模型一致，但演化模型暗示，具有如此低质量和短周期的WD必须具有氦核。质量和半径的测量结果与氦核模型是一致的，但只有当WD有一个非常薄的氢包层（MH/MWD ≤ 10 - 6）。任何进化模型都没有预测到如此薄的外壳。在修正了WD辐射的影响后，GKVir中次级星星的质量和半径与演化模型一致。SDSSJ 1212 -0123中的第二颗星星的半径比预测的大9%。© 2012作者皇家天文学会月报© 2012 RAS。
We use a combination of X-shooter spectroscopy, ULTRACAM high-speed photometry and SOFI near-infrared photometry to measure the masses and radii of both components of the eclipsing post common envelope binaries SDSSJ121258.25-012310.1 and GKVir. For both systems, we measure the gravitational redshift of the white dwarf (WD) and combine it with light-curve model fits to determine the inclinations, masses and radii. For SDSSJ1212-0123, we find an inclination of i= 857 ± 05, masses of M WD= 0.439 ± 0.002M ⊙ and M sec= 0.273 ± 0.002M ⊙, and radii R WD= 0.0168 ± 0.0003R ⊙ and R sec= 0.306 ± 0.007R ⊙. For GKVir, we find an inclination of i= 895°± 06, masses of M WD= 0.564 ± 0.014M ⊙ and M sec= 0.116 ± 0.003M ⊙ and radii R WD= 0.0170 ± 0.0004R ⊙ and R sec= 0.155 ± 0.003R ⊙. The mass and radius of the WD in GKVir are consistent with evolutionary models for a 50000K carbon-oxygen (CO) core WD. Although the mass and radius of the WD in SDSSJ1212-0123 are consistent with CO core models, evolutionary models imply that a WD with such a low mass and in a short period binary must have a helium core. The mass and radius measurements are consistent with helium core models but only if the WD has a very thin hydrogen envelope (M H/M WD≤ 10 -6). Such a thin envelope has not been predicted by any evolutionary models. The mass and radius of the secondary star in GKVir are consistent with evolutionary models after correcting for the effects of irradiation by the WD. The secondary star in SDSSJ1212-0123 has a radius ~9per cent larger than predicted. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS.