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| 題 名 | 利用參數化的方法研究X光雙星系統X 1916-053的X光光陷之性質=Parameterization Studies of the Properties of the X-Ray Dip for Low Mass X-Ray Binary X 1916-053 |
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| 作 者 | 胡欽評; 周翊; | 書刊名 | 臺北天文館學報 |
| 卷 期 | 3 民94.12 |
| 頁 次 | 頁40-47 |
| 分類號 | 323.85 |
| 關鍵詞 | X光雙星; 緊密雙星; 吸積盤; 超駝峰; 負超駝峰; 光陷; X-ray binary; Close binary; Accretion disk; Superhump; Negative superhump; Dip; |
| 語 文 | 中文(Chinese) |
| 中文摘要 | X 1916-053 是一個由中子星和白矮星所組成的極緊密低質量X 光雙星系統(ultra-compact Low Mass X-ray Binary) 。它的X 光「光陷(dip)∗」的週期和可見光波段的光變週期只有1%的差距。我們利用了新的方法定義出光陷的一 些參數,以利於對光陷的性質做有系統性的研究。在1998 年RXTE 的觀測之中,光陷的寬度有明顯的4.87天的週期性變化,這個變化極可能便是吸積盤的盤面進動(nodal precession)週期。由「負超駝峰」的模型加上吸積盤半徑為1:3共振半徑的假設,我們可以估計出雙星質量比約為q=0.045。此外,結合了24年多的觀測數據,我們發現了這個系統的軌道週期有明顯的變化,變化率為:P& orb / Porb = (1.62 ± 0.34)×10−7 yr −1 ,並為X 光光陷建立一個二階星曆表。由我們觀測到的軌道週期變化量與雙星軌道演化的典型模型所推導出來的結果不吻合。而由「輻射驅動(Radiation Driven)」模型則或許可以解釋這個量。最後,利用光陷的相位統計,我們得知主光陷明顯地比次光陷還要穩定,這代表了造成主光陷的吸積盤隆起結構是在吸積盤的外緣,而不是在中間的環狀結構上。 |
| 英文摘要 | X 1916-053 is an ultra-compact Low Mass X-ray Binary (LMXB) composed of a neutron star and a white dwarf. The period of recurrent X-ray dips and optical modulations are slightly and significantly different with each other. We have developed new methods to parameterize the dip to systematically study its variation to further understand the binary and accretion disk behavior. A 4.87 days periodic variation of the dip width, probably due to the nodal precession of the accretion disk, is clearly seen in the RXTE 1998 observations. The signal of the beat frequency of disk nodal precession and the orbital period is marginally detected in the RXTE 1996 data with epoch folding period search method. From the negative superhump model, the mass ratio can be estimated of q=0.045 with 1:3 resonance disk radius, which is larger than the mass ratio predicted by the superhump model or Roche-lobe filling secondary but in the same order. Combined with more than 24 years' historical data, we found an orbital period derivative P& orb / Porb = (1.62 ± 0.34)×10−7 yr −1 and established a quadratic ephemeris for the X-ray dips. The period derivative seems inconsistent with the prediction of standard model of orbital evolution. On the other hand, the radiation driven model may be proper to interpret the period derivative although the large mass outflow predicted by this model has never been observed in this system. From the statistic of dip phase of primary and secondary dips, we concluded that the primary dips are more stable than the secondary dips, which implies that the bulge which cause the primary dips should be on the outer edge of accretion disk instead of in the 1/2 ring. |
本系統中英文摘要資訊取自各篇刊載內容。