[论文解读] Photometric Mass Estimate for the Compact Component of SS 433: And Yet It Is a Neutron Star

V. P. Goranskij|arXiv (Cornell University)|Oct 24, 2011

Astrophysical Phenomena and Observations参考文献 1被引用 6

一句话总结

本文利用多色测光检测A4–A8型巨星的巴耳末跳变，并通过光谱测光估算星际消光，对SS 433双星系统中致密天体的光度质量进行了估计。分析结果得出中子星质量为1.45 ± 0.20 M⊙，基于一致的天体物理参数和质量-光度关系，否定了黑洞起源的可能性。

ABSTRACT

After 33 years of extensive studies of SS 433, we have learnt much about this unique system with moving emission lines in the spectrum. The orbital inclination is known from spectroscopic observations of moving lines; the distance is derived from radio interferometry of relativistic jets; the mass ratio of its components is determined from X-ray observations of jets' eclipses. In 2005, the accretion donor was detected as an A4 - A8 giant, and its contribution to eclipse light was measured spectroscopically. In the present paper, the A-type star was detected via multicolor photometry on the basis of its Balmer jump. A method is proposed to estimate the interstellar reddening, able to measure the individual law of interstellar absorption for SS 433 from spectrophotometry. The method is based on extracting the energy distribution of the spectral component of a very hot source covered in eclipse and on the comparison of its energy distribution to the Planck energy distribution of a black body with the temperature exceeding 10^6 K. The determination of general parameters of SS 433 leads to fairly accurate estimates of luminosity, radius, and mass of the A star in the system, and consequently leads to an accurate estimate of the mass of the compact component, the source of jets. The latter mass is between 1.25 and 1.87 solar masses. The reasons for overestimating this mass when using the dynamical method are discussed. In our opinion, the presence of a black hole in this system is excluded.

研究动机与目标

• 利用测光与光谱数据确定SS 433中致密组分的质量。
• 通过在食食期间对热源的光谱测光，改进星际消光的估计。
• 通过应用精确的恒星参数与总辐射校正，解决动力学质量估计中的不一致问题。
• 确认致密天体为中子星而非黑洞。
• 利用食食期间A型星对系统光度的贡献，进一步优化致密天体的质量估计。

提出的方法

• 利用多色测光检测A4–A8型巨星的能谱中的巴耳末跳变。
• 通过将食食期间观测到的热源能谱与温度高于10⁶ K的普朗克黑体谱进行比较，估算星际消光。
• 采用射电干涉测量相对论喷流得到的SS 433距离（5.12 ± 0.27 kpc）。
• 应用恒星总辐射校正与温度标定，推导A型星的光度与半径。
• 结合X射线食食获得的质量比与光谱测得的轨道倾角，辅以测光数据，约束致密天体的质量。
• 基于食食成分的光谱测光数据，开发了一种独立的星际消光律测定方法。

实验结果

研究问题

• RQ1 基于测光与光谱约束，SS 433中致密天体的质量是多少？
• RQ2 能否利用食食期间热源的能谱准确测量星际消光？
• RQ3 为何SS 433的动力学质量估计会高估致密天体的质量？
• RQ4 SS 433中的致密天体是中子星还是黑洞？
• RQ5 A型星对系统光度的贡献如何影响致密天体的质量估计？

主要发现

• 通过多色测光中的巴耳末跳变，成功检测到A4–A8型巨星，证实其存在于该系统中。
• 基于与温度高于10⁶ K的普朗克黑体谱比较，采用光谱测光方法估算星际消光。
• 致密天体的质量被限制在1.25至1.87 M⊙之间，仅基于测光数据的最佳估计为1.45 ± 0.20 M⊙。
• 所得质量与接近钱德拉塞卡极限的中子星一致，否定了黑洞起源。
• 动力学质量估计的偏差归因于对高吸积率下A型星质量-光度关系的误用。
• 本研究结论认为，SS 433的基本参数与天体物理数据均不支持黑洞模型，若采用该模型则需根本性修正。