标题： 高分辨率X射线能谱的致密双星超软X射线源CAL 87 显示英文标题

标题： High resolution X-ray spectra of the compact binary supersoft X-ray source CAL 87

摘要： 在这项研究中，我们分析了通过{\it 查德雷}高级CCD成像光谱仪（ACIS）相机和低能传输光栅（LETG）在2001年8月观测以及在2003年4月通过{\it XMM-Newton}观测到的掩食超软X射线双星CAL 87的存档X射线数据。在两个不同的日期，高分辨率X射线光谱几乎没有变化。 在此曝光期间的平均未吸收X射线光度在2001年为 4.64$-$5.46$\times10^{36}$ergs s$^{-1}$，在2003年为 4.54$-$4.82$\times10^{36}$ergs s$^{-1}$，其中具有显著红移的发射线，主要来自氮、氧、铁和氩元素，至少占X射线流量的30%。连续谱X射线流量对于一颗炽热且进行氢燃烧的白矮星来说，至少小了一个数量级。 然而，连续谱流量与汤姆逊散射一致，反映了约 5% 来自有效温度为 800,000 K 的氢燃烧白矮星的光，其质量为$\sim$ 1.2 M$_\odot$。 之前已经注意到，一个大的汤姆逊散射日冕可以解释 CAL 87 的 X 射线掩食现象，在该现象中被掩食区域的大小约为一个太阳半径。 发射线起源于更远的被掩食的中心 X 射线源之外的区域；发射光谱非常复杂，具有不寻常的线比值。 显示英文摘要

摘要： In this study, we present an analysis of the archival X-ray data of the eclipsing supersoft X-ray binary CAL 87 observed with the {\it Chandra} Advanced CCD Imaging Spectrometer (ACIS) camera and Low Energy Transmission Grating (LETG) in 2001 August and with {\it XMM-Newton} in 2003 April. The high resolution X-ray spectra are almost unchanged in the two different dates. The average unabsorbed X-ray luminosity during the exposure was 4.64$-$5.46$\times10^{36}$ ergs s$^{-1}$ in 2001 and 4.54$-$4.82 $\times10^{36}$ ergs s$^{-1}$ in 2003, with prominent and red-shifted emission lines, mostly of nitrogen, oxygen, iron and argon, contributing to at least 30\% of the X-ray flux. The continuum X-ray flux is at least an order of magnitude too small for a hot, hydrogen burning WD. However, the continuum flux is consistent with Thomson-scattering reflecting about 5\% of the light of a hydrogen burning WD with effective temperature of 800,000 K, and a mass of $\sim$ 1.2 M$_\odot$. It has been noted before that a large Thomson-scattering corona explains the X-ray eclipse of CAL 87, in which the eclipsed region is found to be of size the order of a solar radius. The emission lines originate in an even more extended region, beyond the eclipsed central X-ray source; the emission spectrum is very complex, with unusual line ratios.