Three classical Cepheid variable stars in the nuclear bulge of the Milky Way
Three classical Cepheid variable stars in the nuclear bulge of the Milky Way
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DOI：
10.1038/nature10359
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发表时间：
2011-09
期刊：
影响因子：
64.8
通讯作者：
N. Matsunaga;T. Kawadu;S. Nishiyama;T. Nagayama;N. Kobayashi;M. Tamura;G. Bono;M. Feast;T. Nagata
中科院分区：
文献类型：
--
作者：
N. Matsunaga;T. Kawadu;S. Nishiyama;T. Nagayama;N. Kobayashi;M. Tamura;G. Bono;M. Feast;T. Nagata
核球是一个半径约为200秒差距的区域，围绕银河系中心。它包含的恒星年龄从几百万年到十几亿年不等，但它的恒星形成历史和星星形成的触发过程仍有待解决。最近，有人提出由气体含量变化提供动力的幕式星星形成。经典造父变星的脉动周期随年龄的增加而减小，因此，根据它们的周期分布来探讨恒星的形成历史是可能的。在这里，我们报告存在三个经典造父变星在核球的脉动周期约为20天，在40秒差距（投影距离）的中央黑洞。没有发现周期更长或更短的造父变星，我们推断，大约在2500万年前有一个时期，可能一直持续到最近，相对于3000 - 7000万年前的时期，星星的形成有所增加。
The nuclear bulge is a region with a radius of about 200 parsecs around the centre of the Milky Way. It contains stars with ages,,ranging from a few million years to over a billion years, yet its star-formation history and the triggering process for star formation remain to be resolved. Recently, episodic star formation, powered by changes in the gas content, has been suggested. Classical Cepheid variable stars have pulsation periods that decrease with increasing age, so it is possible to probe the star-formation history on the basis of the distribution of their periods,. Here we report the presence of three classical Cepheids in the nuclear bulge with pulsation periods of approximately 20 days, within 40 parsecs (projected distance) of the central black hole. No Cepheids with longer or shorter periods were found. We infer that there was a period about 25 million years ago, and possibly lasting until recently, in which star formation increased relative to the period of 30–70 million years ago.