论文标题
V363 CAS：新的富含锂的银河系头
V363 Cas: a new lithium rich Galactic Cepheid
论文作者
论文摘要
经典的头孢虫（DCEP）不仅是确定宇宙距离梯子的标准蜡烛，而且还作为恒星进化论的测试台，这是由于它们的脉动之间的严格联系[周期（S），振幅]和恒星（Luminosity，质量，质量，有效的温度，金属）参数。我们旨在揭示银河系DCEP V363 CA的性质和其他DCEP，显示出锂在其大气中的宇宙丰富性。我们已经收集了三个带有HARPS-N@TNG的V363 CA的高分辨率高分辨率光谱。准确的恒星参数：为该恒星测量有效温度，重力，微扰动，径向速度和金属丰度。我们检测到a（li）= 2.86+-0.10 dex的锂丰度以及[Fe/H] = -0.30+-0.12 dex的铁，碳和氧丰度，[c/h] = -0.06+-0.15 dex和[o/h] V363 CAS是DCEPS的银河系中的第五名。对跨越一百年间隔的历史时间序列的分析表明，V363 CAS的周期正在增加，HJD = 2453000后的加速度急剧。这是不稳定带的第一次穿越的明显提示。我们的结果有利于五个银河液体富含DCEP的情况，首先是在其主序列阶段具有缓慢旋转的祖细胞的不稳定性条。
Classical Cepheids (DCEPs) are important astrophysical objects not only as standard candles in the determination of the cosmic distance ladder, but also as a testbed for the stellar evolution theory, thanks to the strict connection between their pulsation [period(s), amplitudes] and stellar (luminosity, mass, effective temperature, metallicity) parameters. We aim at unveiling the nature of the Galactic DCEP V363 Cas and other DCEPs showing cosmic abundances of lithium in their atmospheres. We have collected three epochs high-resolution spectroscopy for V363 Cas with HARPS-N@TNG. Accurate stellar parameters: effective temperatures, gravities, micro-turbulences, radial velocities, and metal abundances were measured for this star. We detected a lithium abundance of A(Li)=2.86+-0.10 dex, along with iron, carbon and oxygen abundances of [Fe/H]=-0.30+-0.12 dex, [C/H]=-0.06+-0.15 dex and [O/H]=0.00+-0.12 dex. V363 Cas is the fifth among the Milky Way DCEPs to exhibit a Li-rich feature. An analysis of historical time-series spanning a hundred year interval shows that the period of V363 Cas is increasing, with a sharp acceleration after HJD=2453000. This is a clear hint of first crossing of the instability strip. Our results favour the scenario in which the five Galactic Li-rich DCEPs are first-crossing the instability strip having had slowly-rotating progenitors during their main sequence phase.
