High-Dispersion Spectroscopy of the X-Ray Transient RXTE J0421+560 (=CI Camelopardalis) during Outburst
High-Dispersion Spectroscopy of the X-Ray Transient RXTE J0421+560 (=CI Camelopardalis) during Outburst
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爆发期间 X 射线瞬态 RXTE J0421 560（= CI Camelopardalis）的高色散光谱
DOI：
10.1086/324715
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
W. Welsh
中科院分区：
文献类型：
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作者：
E. L. Robinson;I. Ivans;W. Welsh
我们在XTE J 0421 +560的光学对应物CI Cam于1998年4月达到短暂爆发峰值2周后获得了其高色散光谱。光学对应物是一颗超巨星B[e]星星，它发出双分量风，一种是冷的低速风，另一种是热的高速风。冷风是中性和电离金属窄发射线的来源，其速度为32 km s-1，温度接近8000 K。它是致密的，大致呈球形，充满了sgB[e]星星周围的空间，根据系统周围红外辐射尘埃壳的大小，它的半径在13到50 Au之间。它以很高的速率带走质量，速率> 10-6 M yr-1。热风的速度超过2500 km s-1，温度为1.7 ± 0.3 × 104 K。根据2000年3月哈勃空间望远镜获得的CI Cam的紫外光谱图，导出了微分消光系数E（B-V）= 0.85 ± 0.05。我们证明了到CI Cam的距离大于5 kpc。根据这个修正后的距离，爆发峰值的X射线光度为L（2-25 keV）> 3.0 × 1038尔格·s-1，使CI Cam成为最明亮的X射线瞬变之一。在2-25 keV波段，其静态亮度与峰值亮度之比Lq/Lp < 1.7 × 10 ~（-6）。CI Cam中的紧凑型星星沉浸在sgB[e]星星的密集星周风中，并在风中钻洞，除了罕见的短暂爆发外，几乎没有产生X射线辐射。这张照片，一颗紧凑的星星在一个宽阔的轨道上穿过一颗sgB[e]星星的致密拱星包层，偶尔产生短暂的X射线爆发，使CI Cam在已知的X射线双星中独一无二。有强有力的间接证据表明，致密物体是一个黑洞，而不是一个中子星星。我们推测X射线爆发是短暂的，因为致密星星周围的吸积盘是由恒星风供给的，比罗氏瓣溢出供给的盘小。
We obtained high-dispersion spectroscopy of CI Cam, the optical counterpart of XTE J0421+560, 2 weeks after the peak of its short outburst in 1998 April. The optical counterpart is a supergiant B[e] star that is emitting a two-component wind, a cool, low-velocity wind and a hot, high-velocity wind. The cool wind, which is the source of narrow emission lines of neutral and ionized metals, has a velocity of 32 km s-1 and a temperature near 8000 K. It is dense, roughly spherical, fills the space around the sgB[e] star, and, based on the size of an infrared-emitting dust shell around the system, extends to a radius between 13 and 50 AU. It carries away mass at a high rate, Ṁ > 10-6 M☉ yr-1. The hot wind has a velocity in excess of 2500 km s-1 and a temperature of 1.7 ± 0.3 × 104 K. From an ultraviolet spectrogram of CI Cam obtained in 2000 March with Hubble Space Telescope, we derive a differential extinction E(B-V) = 0.85 ± 0.05. We show that the distance to CI Cam is greater than 5 kpc. Based on this revised distance, the X-ray luminosity at the peak of the outburst was L(2-25 keV) > 3.0 × 1038 ergs s-1, making CI Cam one of the most luminous X-ray transients. The ratio of quiescent luminosity to peak luminosity in the 2-25 keV band is Lq/Lp < 1.7 × 10-6. The compact star in CI Cam is immersed in the dense circumstellar wind from the sgB[e] star and burrows through the wind, producing little X-ray emission except for rare transient outbursts. This picture, a compact star traveling in a wide orbit through the dense circumstellar envelope of a sgB[e] star, occasionally producing transient X-ray outbursts, makes CI Cam unique among the known X-ray binaries. There is strong circumstantial evidence that the compact object is a black hole, not a neutron star. We speculate that the X-ray outburst was short because the accretion disk around the compact star is fed from a stellar wind and is smaller than disks fed by Roche lobe overflow.