A first orbital solution for the very massive 30 Dor main-sequence WN6h+O binary R145
A first orbital solution for the very massive 30 Dor main-sequence WN6h+O binary R145
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超大质量 30 Dor 主序 WN6h O 双星 R145 的第一个轨道解
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发表时间：
2009
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通讯作者：
N. Morrell
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作者：
O. Schnurr;O. Schnurr;A. Moffat;A. Villar;N. St;N. Morrell
我们报道了对大麦哲伦星云中大质量、富氢的WN6h恒星R144(HD 38282=BAT99-118=BREY 89)和R145(HDE 269928=BAT99-119=BREY 90)的光谱和偏振研究结果。这两颗恒星都被先前的研究怀疑为双星(R144：SchNurr等人；R145：Moffat)。我们将这两项研究的径向速度(RV)数据与之前未发表的偏振数据相结合。对于R145，我们首次建立了158.8天的轨道周期，以及包括倾角i在内的全套轨道参数，发现i=38°±9°。通过应用Demers等人开发的移位相加方法的修改版本，我们能够分离出这颗非常微弱的伴星的光谱特征。因此，根据R145中两个分量的RV幅度，我们能够估计它们的绝对质量。对于WR组分和O组分，最小质量M WR sin 3 i=116±33 M⊙和Mo sin 3 i=48±20 M⊙。因此，如果低倾角是正确的，得到的组件的绝对质量将分别至少为300M和125M⊙。然而，当R145与NGC 3603-A1或WR20a等已知质量非常高的系统进行比较时，亮度考虑并不支持如此高的质量。接近90°的倾斜角可以弥补这种情况，但目前的数据排除了这种情况。因此，需要更多和更好的数据来坚定地确定这个令人费解、但可能非常庞大和重要的系统的性质。然而，对于R144，组合数据集不足以发现任何周期性。
We report the results of a spectroscopic and polarimetric study of the massive, hydrogen-rich WN6h stars R144 (HD 38282 = BAT99-118 = Brey 89) and R145 (HDE 269928 = BAT99-119 = Brey 90) in the Large Magellanic Cloud. Both stars have been suspected to be binaries by previous studies (R144: Schnurr et al.; R145: Moffat). We have combined radial-velocity (RV) data from these two studies with previously unpublished polarimetric data. For R145, we were able to establish, for the first time, an orbital period of 158.8 d, along with the full set of orbital parameters, including the inclination angle i, which was found to be i = 38° ± 9°. By applying a modified version of the shift-and-add method developed by Demers et al., we were able to isolate the spectral signature of the very faint line companion star. With the RV amplitudes of both components in R145, we were thus able to estimate their absolute masses. We find minimum masses M WR sin 3 i = 116 ± 33 M ⊙ and M o sin 3 i = 48 ± 20 M ⊙ for the WR and the O component, respectively. Thus, if the low-inclination angle were correct, resulting absolute masses of the components would be at least 300 and 125 M ⊙ , respectively. However, such high masses are not supported by brightness considerations when R145 is compared to systems with known very high masses such as NGC 3603-A1 or WR20a. An inclination angle close to 90° would remedy the situation, but is excluded by the currently available data. More and better data are thus required to firmly establish the nature of this puzzling, yet potentially very massive and important system. As to R144, however, the combined data sets are not sufficient to find any periodicity.