We used high spatial resolution images acquired with the Wide Field Camera 3 on board Hubble Space Telescope to probe the population of variable blue straggler stars (BSSs) in the central region of the poorly studied Galactic globular cluster NGC?6541. The time sampling of the acquired multiwavelength (F390W, F555W, and F814W) data allowed us to discover three WUMa stars and nine SX Phoenicis. Periods, mean magnitudes, and pulsation modes have been derived for the nine SX Phoenicis, and their masses have been estimated by using pulsation equations obtained from linear nonadiabatic models. We found masses in the range 1.0-1.1?M ☉, with an average value of 1.06 ± 0.09 M ☉ (σ = 0.04), significantly in excess of the cluster main-sequence turn-off mass (~0.75 M ☉). A mild trend between mass and luminosity seems also to be present. The computed pulsation masses turn out to be in very good agreement with the predictions of evolutionary tracks for single stars, indicating values in the range ~1.0-1.2 M ☉ for most of the BSS population, in agreement with what was discussed in a number of previous studies.
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机译:我们使用哈勃太空望远镜上的广角相机3所获得的高分辨率图像来探测在研究欠佳的银河系球状星团NGC?6541的中心区域中的蓝色散杂散恒星(BSS)的数量。对获取的多波长(F390W,F555W和F814W)数据进行时间采样后,我们可以发现三颗WUMa星和九颗SX腓尼基星。推导了九个SX腓尼基的周期,平均幅度和脉动模式,并使用从线性非绝热模型获得的脉动方程估算了它们的质量。我们发现质量在1.0-1.1?M range范围内,平均值为1.06±0.09 M☉(σ= 0.04),大大超过簇主序列关闭质量(〜0.75 M☉)。质量和光度之间也存在温和的趋势。计算出的脉动质量与单颗恒星的演化轨迹的预测非常吻合,表明大多数BSS群体的值在〜1.0-1.2 M range范围内,与许多之前的学习。
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