HgMn恒星HD 11753表面钛、锶和钇斑点的动力学演化
Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753
摘要：
目标。我们收集了三颗典型的HgMn（汞锰）星HD 11753，HD 53244和HD 221507的大约100个高分辨率光谱，以寻找缓慢脉动的B类脉动和各种化学元素的表面不均匀分布。方法.经典的频率分析方法被用来检测线轮廓的变化，并确定变化的周期。通过多普勒成像重建得到了恒星表面化学元素丰度图。结果对于HD 11753，这是最显着的变化，不同的谱线轮廓的变化被检测到的Ti，Sr，Y，Zr和Hg，而对于HD 53244和HD 221507最可变的线轮廓分别属于元素Hg和Y。根据径向速度和谱线等效宽度的变化，我们得到了这三颗星的自转周期：P_rot（HD 11753）= 9.54d，P_rot（HD 53244）= 6.16d，P_rot（HD 221507）= 1.93d。对于HD 11753，使用相隔约65天的两个数据集，应用多普勒成像技术推导出最易变元素Ti、Sr和Y的分布。多普勒成像重建的结果显示了显着的变化，表面分布的TiII，SrII，和YII的数据集之间，表明迄今为止没有很好地理解的物理过程中的恒星辐射信封，导致一个相当快的动态化学斑点的演变。
英文摘要：
Aims. We gathered about 100 high-resolution spectra of three typical HgMn (mercury-manganese) stars, HD 11753, HD 53244, and HD 221507, to search for slowly pulsating B-like pulsations and surface inhomogeneous distribution of various chemical elements. Methods. Classical frequency analysis methods were used to detect line profile variability and to determine the variation period. Doppler imaging reconstruction was performed to obtain abundance maps of chemical elements on the stellar surface. Results. For HD 11753, which is the star with the most pronounced variability, distinct spectral line profile changes were detected for Ti, Sr, Y, Zr, and Hg, whereas for HD 53244 and HD 221507 the most variable line profiles belong to the elements Hg and Y, respectively. We derived rotation periods for all three stars from the variations of radial velocities and equivalent widths of spectral lines belonging to inhomogeneously distributed elements: P_rot (HD 11753)=9.54 d, P_rot (HD 53244)=6.16 d, and P_rot (HD 221507)=1.93 d. For HD 11753 the Doppler imaging technique was applied to derive the distribution of the most variable elements Ti, Sr, and Y using two datasets separated by ~65 days. Results of Doppler imaging reconstruction revealed noticeable changes in the surface distributions of TiII, SrII, and YII between the datasets, indicating the hitherto not well understood physical processes in stars with radiative envelopes that cause a rather fast dynamical chemical spot evolution.
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