Time-resolved spectral analysis of the pulsating helium star V652 Her
Time-resolved spectral analysis of the pulsating helium star V652 Her
复制标题
脉动氦星 V652 Her 的时间分辨光谱分析
DOI：
--
复制
发表时间：
2001
期刊：
影响因子：
--
通讯作者：
D. Pollacco
中科院分区：
文献类型：
--
作者：
C. Jeffery;V. Woolf;D. Pollacco
用威廉·赫歇尔望远镜获得了脉动氦星星V652 Her的59个中分辨率高信噪比光谱，它们覆盖了1.06个脉动周期。这些已被补充的档案紫外线和可见分光光度法，并用于使一个随时间变化的研究V652她在整个脉动周期的属性。本研究包括以下特点：迄今为止测量的V652 Her最精确的径向速度曲线，用于自动测量有效温度，表面重力和中等分辨率光谱的投影旋转速度的新软件，脉动周期周围有效温度和表面重力的自洽高精度测量，在最小半径处过度谱线增宽的证明和脉动驱动激波阵面的证据，一种仅使用径向速度和表面重力测量直接测量脉动星星半径的新方法，用于自动测量化学丰度和微湍流速度的新软件，与以前的工作（论文IV）相比，更新V652 Her的化学丰度，总通量变化的重新分析（参见论文II）与以前的工作很好地吻合，并修订了恒星质量和半径的测量，这是类似于最近的结果，另一个脉动氦星星，BX Cir。在没有参考紫外线通量的情况下测量的质量被证明是不符合物理学的低（10.18 M）。V652 Her在脉动周期内的平均尺寸的最佳估计值由下式给出：T_（eff）= 22930 ± 10K，T_（log）g_（eff）= 3.46 ± 0.05（电离平衡），δ Teff δ = 20 950 ± 70 K（总通量法），δ R δ = 2.31 ± 0.02 R，δ L δ = 919 ± 14 L，M = 0.59 ± 0.18 M，d = 1.70 ± 0.02 kpc。遇到了两个重大问题。所使用的线覆盖的缺氢模型大气从光谱（电离平衡）和视觉和紫外光度（热通量）产生不一致的有效温度。其次，IUE谱在相位上分布不好，并且具有低信噪比。这些问题可能会引入高达0.1 M的系统误差。
A series of 59 moderate-resolution high signal-to-noise spectra of the pulsating helium star V652 Her covering 1.06 pulsation cycles was obtained with the William Herschel Telescope. These have been supplemented by archival ultraviolet and visual spectrophotometry and used to make a time-dependent study of the properties of V652 Her throughout the pulsation cycle. This study includes the following features: the most precise radial velocity curve for V652 Her measured so far, new software for the automatic measurement of effective temperature, surface gravity and projected rotation velocities from moderate-resolution spectra, self-consistent high-precision measurements of effective temperature and surface gravity around the pulsation cycle, a demonstration of excessive line-broadening at minimum radius and evidence for a pulsation-driven shock front, a new method for the direct measurement of the radius of a pulsating star using radial velocity and surface gravity measurements alone, new software for the automatic measurement of chemical abundances and microturbulent velocity, updated chemical abundances for V652 Her compared with previous work (Paper IV), a reanalysis of the total flux variations (cf. Paper II) in good agreement with previous work, and revised measurements of the stellar mass and radius which are similar to recent results for another pulsating helium star, BX Cir. Masses measured without reference to the ultraviolet fluxes turn out to be unphysically low (∼0.18 M ). The best estimate for the dimensions of V652 Her averaged over the pulsation cycle is given by: 〈Teff〉 = 22 930 ± 10 K and 〈log g〉 = 3.46 ± 0.05 (ionization equilibrium), 〈Teff〉 = 20 950 ± 70 K (total flux method), 〈R〉 = 2.31 ± 0.02 R , 〈L〉 = 919 ± 14 L , M = 0.59 ± 0.18 M and d = 1.70 ± 0.02 kpc. Two significant problems were encountered. The line-blanketed hydrogen-deficient model atmospheres used yield effective temperatures from the optical spectrum (ionization equilibrium) and visual and UV photometry (bolometric flux) that are inconsistent. Secondly, the IUE spectra are poorly distributed in phase and have low signal-to-noise. These problems may introduce systematic errors of up to 0.1 M .