A TiO study of the black hole binary GRO J0422+32 in a very low state
A TiO study of the black hole binary GRO J0422+32 in a very low state
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DOI：
10.1046/j.1365-8711.2000.03608.x
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发表时间：
2000-04
影响因子：
4.8
通讯作者：
N. Shahbaz
中科院分区：
文献类型：
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作者：
N. Shahbaz
我们提出了53同时测光（I波段）和光谱（6900-9500 A）的观测GRO J 0422 +32，在1997年12月。根据这些数据，我们确定J 0422 +32处于观测到的最低状态，I=20.44±0.08。使用相对分光光度法，我们表明，这是可能的，非常准确地校正大地吸收。在此之后，我们使用7055和7589 A的TiO带进行径向速度研究，从而获得378±16 km s −1的半振幅，得出f（M）=1.191±0.021 M，与以前的观测结果一致。我们进一步证明，这种很少探索的方法是非常强大的这样的系统。我们还确定了一个新的轨道星历HJD=245 0274.4156±0.0009+0.212 1600±0.000 0002 E，并得到了一些椭球调制的证据，由此确定J 0422 +32的轨道倾角小于45°。因此，我们计算出主星的最小质量为2.22 M质量，与黑洞一致，但不一定是Beekman等人最近（1997年）提出的超大质量黑洞。我们得到了次级星星的M4-5光谱类型，并确定次级贡献了我们在6950-8400 A范围内从J 0422 +32观测到的通量的38± 2%。由此我们计算到系统的距离为1.39±0.15 kpc。
We present 53 simultaneous photometric (I band) and spectroscopic (6900–9500 A) observations of GRO J0422+32, taken during 1997 December. From these we determine that J0422+32 was in its lowest state yet observed, at I=20.44±0.08. Using relative spectrophotometry, we show that it is possible to correct very accurately for telluric absorption. Following this, we use the TiO bands at 7055 and 7589 A for a radial velocity study and thereby obtain a semi-amplitude of 378±16 km s −1 , which yields f(M)=1.191±0.021 M ⊙ and consistent with previous observations. We further demonstrate that this little-explored method is very powerful for such systems. We also determine a new orbital ephemeris of HJD=245 0274.4156±0.0009+0.212 1600±0.000 0002E.We see some evidence for an ellipsoidal modulation, from which we determine the orbital inclination of J0422+32 to be less than 45°. We therefore calculate a minimum mass for the primary of 2.22 M ⊙ , consistent with a black hole, but not necessarily the supermassive one proposed recently (1997) by Beekman et al. We obtain an M4–5 spectral type for the secondary star, and determine that the secondary contributes 38±2 per cent of the flux that we observe from J0422+32 over the range 6950–8400 A. From this we calculate the distance to the system to be 1.39±0.15 kpc.