Blue large-amplitude pulsators as a new class of variable stars
Blue large-amplitude pulsators as a new class of variable stars
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DOI：
10.1038/s41550-017-0166
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发表时间：
2017-06
期刊：
影响因子：
14.1
通讯作者：
P. Pietrukowicz;W. Dziembowski;M. Latour;R. Angeloni;R. Poleski;F. Di Mille;I. Soszyński;A. Udalski;M. Szymański;Ł. Wyrzykowski;S. Kozłowski;J. Skowron;D. Skowron;P. Mróz;M. Pawlak;K. Ulaczyk
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文献类型：
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作者：
P. Pietrukowicz;W. Dziembowski;M. Latour;R. Angeloni;R. Poleski;F. Di Mille;I. Soszyński;A. Udalski;M. Szymański;Ł. Wyrzykowski;S. Kozłowski;J. Skowron;D. Skowron;P. Mróz;M. Pawlak;K. Ulaczyk
在许多恒星中观察到的规则的固有亮度变化是由脉动引起的。这些脉动提供了有关恒星整体和结构参数的信息。脉动周期从几秒到几年不等，具体取决于恒星的致密性和形成其外层的物质的性质。在这里，我们报告发现了十多颗以前未知的短周期变星：蓝色大振幅脉动星。这些物体在光学通带中表现出非常规则的亮度变化，周期在 20-40 分钟范围内，幅度在 0.2-0.4 幅范围内。相控光变曲线具有特征性的锯齿形状，类似于经典造父变星和以基本模式脉动的天琴座RR型恒星的形状。这些天体比在同一视野中观察到的主序星明显更蓝，这表明它们都是热星。后续光谱证实了约 30,000 K 的高表面温度。循环过程中的温度和颜色变化证明了变量的脉动性质。然而，在任何已知类型的恒星（包括热天体）中都没有观察到如此短周期的大幅脉动。长期光度观测表明，变星随着时间的推移非常稳定。导出的周期变化率约为每年 10−7，并且在大多数情况下为正值。根据脉动理论，这种大幅度的振荡可能发生在具有膨胀的富氦包层的演化中的低质量恒星中。可能导致这种恒星结构的进化路径仍然未知。
Regular intrinsic brightness variations observed in many stars are caused by pulsations. These pulsations provide information on the global and structural parameters of the star. The pulsation periods range from seconds to years, depending on the compactness of the star and properties of the matter that forms its outer layers. Here, we report the discovery of more than a dozen previously unknown short-period variable stars: blue large-amplitude pulsators. These objects show very regular brightness variations with periods in the range of 20–40 min and amplitudes of 0.2–0.4 mag in the optical passbands. The phased light curves have a characteristic sawtooth shape, similar to the shape of classical Cepheids and RR Lyrae-type stars pulsating in the fundamental mode. The objects are significantly bluer than main-sequence stars observed in the same fields, which indicates that all of them are hot stars. Follow-up spectroscopy confirms a high surface temperature of about 30,000 K. Temperature and colour changes over the cycle prove the pulsational nature of the variables. However, large-amplitude pulsations at such short periods are not observed in any known type of stars, including hot objects. Long-term photometric observations show that the variable stars are very stable over time. Derived rates of period change are of the order of 10−7per year and, in most cases, they are positive. According to pulsation theory, such large-amplitude oscillations may occur in evolved low-mass stars that have inflated helium-enriched envelopes. The evolutionary path that could lead to such stellar configurations remains unknown.